Current Events Archive

Current Events

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(Added 12/31/03) The end of a long journey has begun an even longer mission for the European Space Agency's Mars Express orbiter. On Christmas Day - December 25, 2003 - the 205-day and 400 million km (250 million miles) journey placed Mars Express in orbit around Mars after a 37 minute main engine burn at 03:47 CET.

The burn's purpose was to match the probe's speed with Mars'. This represent's Europe's first attempt to send a space craft into orbit around another planet, and it has been deemed a complete success. However, the initial orbit sets the craft around Mars' equator, and the main mission requires an 86° polar orbit. On December 30, at the farthest point in its highly elliptical orbit, Mars Express executed another main engine burn and slipped into a polar orbit. Further refinements through January 4, 2004, will place Mars Express into its final orbit.

At about the same time Mars Express entered its initial orbit, the small lander, Beagle 2, was supposed to have landed on the Martian surface. However, all attempts to contact the probe to date (using NASA's Mars Odyssey craft and several Earth-based radio telescopes) have proved unsuccessful. It is hoped that once Mars Express reaches its final science orbit in early January that it will have more luck. Mission personnel are still hopeful that the probe was not destroyed.

Adapted from the press release on http://www.esa.int/export/esaCP/SEMAD8374OD_index_0.html and Spaceflight Now's website http://spaceflightnow.com/mars/marsexpress/status.html and http://spaceflightnow.com/mars/marsexpress/031230marsexpressorbit.html.

(Added 12/21/03) The European Southern Observatory (ESO) has released three images of dusty spiral galaxies that show large areas of intense star formation. Astronomers Mark Neeser from the Universitäts-Sternwarte München (Germany) and Peter Barthel from the Kapteyen Institute in Groningen (the Netherlands) used the ESO's Very Large Telescope (VLT) to take these images during twilight when they had to stop their normal observing program - searching for very distant and faint quasars.

NGC 613

NGC 1792

NGC 3627

NGC 613 is a barred spiral galaxy in the southern constellation Sculptor. The galaxy is inclined by 32° and, contrary to most barred spirals, has many arms that give it a tentacular appearance.

Prominent dust lanes are visible along the large-scale bar. Extensive star formation occurs in this area, at the ends of the bar, and also in the nuclear regions of the galaxy.

The gas at the center, as well as the radio properties, are indicative of the presence of a massive black hole in the center of NGC 613.

NGC 1792 is located in the southern constellation Columba (The Dove) and is a so-called starburst spiral galaxy. Its optical appearance is quite chaotic due to the patchy distribution of dust throughout the disc of this galaxy. It is very rich in neutral hydrogen gas - fuel for the formation of new stars - and is rapidly forming such stars. The galaxy is characterized by unusually luminous far-infrared radiation; this is due to dust heated by young stars.

NGC 3627, also known as M66 is located in the constellation Leo (The Lion). It is a spiral with a well-developed central bulge. It also displays large-scale dust lanes. Many regions of warm hydrogen gas are seen throughout the disc of this galaxy. The latter regions are being ionized by radiation from clusters of newborn stars. Very active star-formation is most likely also occurring in the nuclear regions of NGC 3627.

The galaxy forms, together with its neighbors M65 and NGC 3628, the "Leo Triplet;" they are located at a distance of about 35 million light-years.

M66 is the largest of the three. Its spiral arms appear distorted and displaced above the main plane of the galaxy. The asymmetric appearance is most likely due to gravitational interaction with its neighbors.

Adapted from the press release on http://www.eso.org/outreach/press-rel/pr-2003/phot-33-03.html.

(Added 12/19/03) Since its launch on June 2, 2003, the ESA's Mars Express craft has been carrying the Beagle 2 lander on its journey to Mars. At 9:31 CET on December 19, 2003, the craft flawlessly released the Beagle 2, which is now scheduled to land on Mars on December 25, Christmas Day.

The release was accomplished via a slowly fired pyrotechnic device that released a loaded spring. The spring gently pushed the Beagle 2, named for the ship upon which Charles Darwin sailed, away from the mother craft. Beagle 2 has no propulsion system of its own, so a December 16 maneuver by Mars Express was needed to ensure Beagle 2 will not approach Mars a too steep nor too shallow an entry angle.

Adapted from the press release on http://www.esa.int/export/esaCP/Pr_83_2003_p_EN.html.

(Added 12/19/03) NASA's Great Observatories program involves four space telescopes that are all tuned to look at different types of light: The Hubble Space Telescope observes optical, the Compton Gamma-Ray Observatory can examine gamma-rays, the Chandra X-Ray Observatory records x-rays, and now the Spitzer Space Telescope (SST) observes the infrared.

Formerly known as the Space Infrared Telescope Facility (SIRTF), the telescope was renamed on December 18, 2003, after the late Dr. Lyman Spitzer, Jr., who was one of the most influential scientists in the 20^th century; in the 1940s, he became the first to propose the placement of telescopes in space.

"The Spitzer Space Telescope takes its place at the forefront of astronomy in the 21^st century, just as its namesake, Dr. Lyman Spitzer Jr., was at the forefront of astronomy in the 20^th," said NASA's Associate Administrator for Space Science Dr. Ed Weiler.

Four images were released in total for the naming ceremony, and they are available at http://www.nasa.gov/multimedia/imagegallery/image_feature_101_sirtf.html. One of the images appears to the left. It shows the dusty, winding arms of a spiral galaxy much like our own; it is M81, and shows the SST's ability to show infrared light in unprecedented detail.

Adapted from the press releases on http://www.jpl.nasa.gov/releases/2003/170.cfm, http://www.nasa.gov/home/hqnews/2003/dec/HQ_03411_newly_named.html, and http://www.nasa.gov/home/hqnews/2003/dec/HQ_03414_sirtf_new_name.html.

(Added 12/17/03) Two of NASA's Mars -orbiting probes, Mars Global Surveyor and Mars Odyssey, have found evidence of a relatively recent ice age on Mars. Unlike Earth ice ages, it appears as if a Martian one grows when the poles warm and water vapor is transported to lower latitudes.

Evidence suggests that the Martian ice ages arise from variations in the planet's orbit and tilt that produce drastic changes in the distribution of water ice from polar regions to mid-equatorial ones. The team of researchers utilized the NASA craft data and analogies to Earth's Antarctic Dry Valleys and report their findings in the December 18/25 edition of Nature.

"Of all the solar system planets, Mars has the climate most like that of Earth. Both are sensitive to small changes in orbital parameters," explains planetary scientist Dr. James Head of Brown University, Providence, RI - the lead author of the study. "Now we're seeing that Mars, like Earth, is in a period between ice ages."

Head and his co-authors examined global patterns of landscape shapes and near-surface water ice the orbiters mapped. The concluded that a covering of water ice mixed with dust covered the surface of Mars to latitudes as low as 30°, and it is degrading and retreating. By the observation of the small number of impact craters in those features and by backtracking the known patterns of changes in the orbit and tilt of Mars, they estimated that the most recent ice age occurred about 400 thousand to 2.1 million years ago.

They believe that the mechanisms that drive the ice age lie in polar warming that drives water vapor from polar ice into the atmosphere. The water then goes back into the ground at lower latitudes as frost or snow mixed with dust. This layering is a few meters thick and smoothes the terrain. When ice on the top evaporates into the atmosphere, it leaves behind an insulating layer of dust over the remaining ice.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/dec/HQ_03415_ice_age.html.

(Added 12/13/03) The most distant object that is visible with the naked eye is the Andromeda Galaxy, also known as M31. It is our nearest sizeable neighbor galaxy, and has been the recent subject of NASA's Galaxy Evolution Explorer (GALEX). This is one of several images that have been released to the public as part of the mission's first collection.

"The Andromeda image gives us a snapshot of the most recent star formation episode," explains Dr. Christopher Martin, GALEX principal investigator and an astrophysics professor at the California Institute of Technology in Pasadena, which leads the mission. "By studying this view of the galaxy in the process of forming stars, we can better understand how that fundamental process works, such as where stars form, how fast, and why."

The image to the right shows the Andromeda Galaxy (M31). It is the most massive of the local group of galaxies that includes our own Milky Way. This image is a mosaic of 10 GALEX images taken in September 2003. The color image is made with red indicating near UV and blue indicating far UV. It shows blue regions of young, hot, high-mass stars in the spiral arms as well as a central bulge of older, cooler stars. Several companion galaxies are also visible, including M32 - a dwarf elliptical directly below the central bulge and just outside the spiral arms - and M110 which is above and to the right of the center.

The collection of images includes several galaxies and star clusters other than Andromeda, such as M2, NGC 7331, NGC 300, NGC 55, NGC 247, M83, NGC 5962, NGC 5474, and NGC 5398.

"It's very rewarding and exciting for the team to see the fruits of their labors," claimed Kerry Erickson, the mission's project manager at NASA's Jet Propulsion Laboratory in Pasadena, CA. "Because people are accustomed to seeing objects in visible light, it's amazing to see how different the universe looks in ultraviolet and how much information is revealed to us by those observations."

Scientists are interested in learning more about M31, including brightness, age, mass, and distribution of young star clusters in its spiral arms. This will provide immense amounts of information on mechanisms of star formation in galaxies, and it will help them to interpret UV and IR observations of other, more distant galaxies.

Adapted from the press release on http://www.jpl.nasa.gov/releases/2003/167.cfm.

(Added 12/10/03) A long time ago, in a galaxy far, far away, a signpost of rapid star formation began its journey through space. Using the National Science Foundation's Very Large Array (VLA) radio telescope, scientists have honed in on this.

The galaxy, 11 billion light-years away, is at a point when the universe was only 20% of its current age. The sign is a huge quantity of dense interstellar gas. This is an indication for the equivalent of 1000 suns per year being produced in this distant galaxy - the farthest ever found with these requirements (discussed below) - which scientists have dubbed the "Cloverleaf."

"This is a rate of star formation more than 300 times greater than that in our own Milky Way and similar spiral galaxies, and our discovery may provide important information about the formation and evolution of galaxies throughout the universe," said Philip Solomon of Stony Brook University, NY.

While the raw material for star formation has been observed in galaxies at even greater distances, the Cloverleaf is the most distant that shows the essential signature of star formation. The signature is in the form of a specific frequency of radio waves emitted by molecules of the gas hydrogen cyanide (HCN). "If you see HCN, you are seeing gas with the high density required to form stars," said Paul Vanden Bout of the National Radio Astronomy Observatory (NRAO).

In the above image, the VLA data (green) is superimposed on Hubble Space Telescope (HST) data of the Cloverleaf. The four images of the Cloverleaf galaxy are a result of gravitational lensing.

Adapted from the press release on http://www.nrao.edu/pr/2003/cloverleaf/.

(Added 12/10/03) NASA's Ramaty High Energy Solar Spectroscopic Imager (RHESSI) spacecraft has provided new information on how the sun forms some of the largest solar flares.

Solar flares, capable of releasing as much energy as one billion one-megaton nuclear bombs, are formed by the destruction of magnetic fields - called magnetic reconnection - according to the leading theory. The RHESSI data confirms this as the most likely scenario.

"Many observations gave hints that magnetic reconnection over large areas was responsible for solar flares, but the new pictures from RHESSI are the first that are really convincing," said Linhui Sui of the Catholic University of America, WA, lead author of a paper on this research published in the October 20 Astrophysical Journal Letters (ApJ Lett.). "The hunt for the energy source of flares has been like a story where villagers suspect a dragon is on the loose because something roars overhead in the middle of the night, but only something resembling the tail of a dragon is ever seen. With RHESSI, we've now seen both ends of the dragon."

Magnetic reconnection can happen in the solar atmosphere because it is hot enough to separate electrons from atoms, producing a gas of electrically charged particles called plasma. Because plasma is electrically charged, magnetic fields and plasma tend to flow together. When magnetic fields and plasma are ejected from the sun, the ends of the magnetic fields remain attached to the surface. As a result, the magnetic fields are stretched and forced together until they break under the stress, like a rubber band pulled too far, and then they reconnect to a new shape with less energy. This is depicted in the illustration above.

The thin region where they reconnect is called the "reconnection layer," and it is where oppositely directed magnetic fields come close enough to merge. This magnetic reconnection could power a solar flare by heating the sun's atmosphere to tens of millions of degrees and accelerating electrically charged particles that make up the plasma to almost the speed of light.

Solar Flare Observed by RHESSI At such high temperatures, solar plasma will shine in x-rays, and RHESSI observed these high-energy x-rays, emitted by plasma, heated to tens of millions of degrees in a 20-minute flare on April 15, 2002. The hot plasma initially appeared in the RHESSI images as a blob atop an arch of relatively cooler plasma protruding from the sun's surface. The blob-and-arch structure is consistent with reconnection, because the x-ray blob could be heated by reconnection, and the part of the magnetic field that breaks and snaps back to the solar surface will assume an arch shape.

These structures have been seen before and hinted at reconnection, but the observations were not conclusive. However, over the course of about four minutes during the most intense part of the flare, the x-ray emitting blob exhibited two characteristics consistent with large-scale magnetic reconnection.

First, the blob split in two, with the top part ultimately rising away from the solar surface at a speed of about 1.1 million km/hr (700,000 mph). This is expected if extensive reconnection is occurring because as the magnetic fields stretch, the reconnection layer also stretches, like taffy being pulled. Plasma heated by reconnection squirts out of the top and bottom of the reconnection layer, forming the two x-ray blobs in the RHESSI pictures when the top and bottom are sufficiently far apart to be resolved as distinct areas.

Second, in both blobs, the area closest to the apparent reconnection layer was hottest, and the area farthest away was coolest, according to temperature measurements by RHESSI. This is also expected if reconnection is occurring because, as the magnetic fields break and reconnect, other magnetic fields nearby move into the reconnection region and reconnect as well, since the overall, large-scale field continues to stretch. Thus, plasma is continuously heated and blasted from the reconnection layer. The plasma closest to the reconnection area is the most recently expelled and therefore the hottest. Plasma farther away was ejected earlier and had time to cool.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/dec/HQ_03397_solar_explosions.html.

(Added 12/10/03) Amidst the flurry of probes that are currently at and en route to Mars, one lone straggler that began its journey over half a decade ago has finally been declared a lost cause. Japanese probe Nozomi - meaning "hope" in Japanese - has passed the deadline for a remedy for the problems it faces with no solution.

The 540 kg (1190 lb) probe was launched in July of 1998 with the destination of Mars. It was supposed to arrive in Martian orbit in October 1999, but initial problems put its trajectory on a much longer path. The initial course was a close approach of Earth in December 1998, but a stuck valve caused an unexpected loss of propellant that left the probe unable to reach Mars under the planned mission.

A new course was charted that involved more passes of Earth to slingshot the probe to Mars that were carried out in December 2002 and June 2003. However, a violent solar flare in April 2002 crippled the craft's power system and communications equipment, among other things. Remote fixes to bring the craft back to full power and perform necessary maneuvers for orbital insertion have not succeeded.

Nozomi's mission was to enter Martian orbit, and from its perch to study such Martian features as the planet's magnetic field and upper atmospheric properties as they interacted with the solar wind, as well as to study Deimos and Phobos - the two small moons of Mars.

The craft will fly past Mars at approximately 1000 km (660 miles) above its surface and will continue in a solar orbit. Despite the failure, officials claim they have learned several important lessons that they will carry into future projects.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/mars/nozomi/031209abandon.html.

(Added 12/09/03) The elliptical galaxy NGC 4261 has some new components, according to recent Chandra X-ray Observatory data. The data, in the left frame of the image to the left, show dozens of bright points indicating never-before seen neutron stars and black holes that stretch over more than 50,000 light-years. The trails are evidence for an ancient galaxy collision.

The optical image of the galaxy - the right frame of the image - shows a relatively benign and unexciting elliptical galaxy. Yet the issue is thought to be in the manner in which many ellipticals form:

A current popular model for elliptical galaxy formation is that two (or more) spiral galaxies merge, and the resulting cauldron of stellar cities is a lenticular elliptical. However, this only happens after many millions - or billions - of years, and in the mean time there are many streams and trails of stars and gas / dust clouds that stretch throughout the vicinity.

The optical evidence for such mergers is thought to fade rather quickly against the luminous background of the galaxy, but the x-ray observations presented here could indicate that the x-ray signs of the mergers could linger for hundreds of millions of years.

"This discovery shows that x-ray observations may be the best way to identify the ancient remains of mergers between galaxies," said Lars Hernquist of the Harvard-Smithsonian Center for Astrophysics in Cambridge (CfA), MA, and a coauthor on an article on the galaxy NGC 4261 in an upcoming issue of the Astrophysical Journal Letters (ApJ Lett.). "It could be a significant tool for probing he origin of elliptical galaxies."

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_120803.html.

(Added 12/06/03) The mushroom-shaped clouds that form the Homunculus Nebula surround the massive star Eta Carinae in the left image in the composite to the right. New VLT data (right in the composite) reveals the inner structure of the nebula that form the immediate surroundings.

Eta Carinae is the most luminous star known in the galaxy. It is 100 times as massive as the sun and over 5 million times as luminous. It has entered the final stages of its life and is highly unstable, undergoing giant outbursts - one of the most recent occurring in 1841 that created the nebula that surrounds it now, and making it the second brightest star in the sky at the time.

A team of astronomers used the NAOS-CONICA adaptive optics camera that is attached to the 8.2 m VLT YEPUN telescope to image the surroundings of Eta Carinae with a resolution of about the size of the solar system. This shows the central region of the nebula, revealing it to be dotted by the star with many luminous "blobs" in the immediate vicinity.

For a sharper image of the nebula, the astronomers then used interferometry - combining the light from two or more telescopes to achieve an image as if it were taken by a telescope as large as the separation between the originals. The astronomers used the VLT INterferometer Commissioning Instrument (VINCI) along with the two 32 cm siderostat test telescopes, achieving a baseline of 62 meters. With these, the astronomers were able to resolve the shape of the outer layer of Eta Carinae, resolving 0.005 arcsec - 11 A.U. at the distance of the star.

The results indicate that the stellar wind about the star is greatly elongated in a ratio of 2:3. The long axis is pointing almost directly along the axis of the two mushroom clouds of the surrounding nebula. This goes against mainstream theories, which state that stars should loose mass mostly around their equator and not the poles due to centrifugal forces from the star's rotation. But if this were so in Eta Carinae's case, then the mushroom clouds should form a torus - a ring.

Adapted from the press release on http://www.eso.org/outreach/press-rel/pr-2003/pr-31-03.html.

(Added 12/06/03) The Hubble Heritage Team has released December's image of a star-forming region in the spiral galaxy M33, NGC 604. 2.7 million light-years from us, NGC 604 lies in the constellation Triangulum; this image covers approximately 2 arcminutes across (1500 light-years). The image was originally taken in July 1994, January 1995, and December 2001, for a total exposure time of 4 hours.

NGC 604 is one of the largest known regions of star birth in a nearby galaxy. It is similar to those in the Milky Way, such as the Orion Nebula, but it is much larger and contains many more recently formed stars.

Over 200 bright blue stars reside in this 1300 light-year across cloud - 100 times the size of the Orion Nebula which contains 4 bright blue stars. The stars in NGC 604 formed approximately 3 million years ago. Most of the hottest and brightest of the stars are in a loose cluster within a cavity near the center of the nebula. Stellar winds and supernova explosions helped to form the cavity.

The most massive stars in the region are over 120 times the sun's mass and posseses surface temperatures as high as 40,000 K (72,000 °F). Ultraviolet radiation from the stars makes the surrounding gas fluoresce.

NGC 604 resides in a spiral arm of M33, which is a member of the Local Group that includes the Milky Way and Andromeda Galaxies.

Adapted from the information on http://heritage.stsci.edu/2003/30/fast_facts.html.

(Added 12/06/03) A television can produce millions of different colors, yet they all have a common origin. In a similar way, astronomers have discovered that a variety of bright cosmic explosions all have the same origin and the same total amount of energy, they just look different.

This is the conclusion of an international team of astronomers that used the National Science Foundation's Very Large Array (VLA) radio telescope to study the closest known gamma-ray burst that was found earlier this year. "For some reason we don't yet understand, these explosions put greatly varying percentages of their explosive energy into the gamma-ray portion of their output," said Dale Frail of the National Radio Astronomy Observatory (NRAO) in Socorro, NM. That means, he said, that both strong and weak gamma-ray bursts, along with X-ray flashes which emit almost no gamma rays, are just different forms of the same cosmic beast. The research team reported their results in the November 13 issue of the scientific journal Nature.

The scientists trained the VLA on a gamma-ray burst discovered using NASA's HETE-2 satellite last March 29. This burst, dubbed GRB 030329, was the closest such burst yet seen, about 2.6 billion light-years from Earth. Because of this relative proximity, the burst was bright, with visible light from its explosion reaching a level that could be seen in amateur telescopes. As the burst faded, astronomers noted an underlying distinctive signature of a supernova explosion, confirming that the event was associated with the death of a massive star.

Since 1999, astronomers have known that the strong outbursts of gamma rays, X-rays, visible light, and radio waves from these bursts form beams, like those from a flashlight, rather than spreading in all directions, like light from a bare bulb. The surprising result from the VLA studies of GRB 030329 is that there are two beams, not one. The scientists found that the gamma rays and the early visible light and X-ray emission were coming from a narrow beam, while the radio waves and later visible-light emission came from another, wider beam.

"The strange thing is that some explosions seem to put most of their energy into the narrow beam, while others put most or nearly all their energy into the wider beam," Frail said. "This is telling us something very fundamental about the inner workings that drive these explosions."

The mechanism producing these explosions is what scientists call a collapsar, which occurs when a giant star collapses of its own weight at the end of its normal, nuclear fusion-powered lifetime. In an ordinary supernova, such a collapse produces a neutron star. A collapsar, however, marks the death of a more-massive star and results in a black hole, a concentration of mass so dense that not even light can escape it. After the black hole forms, its powerful gravitational pull pulls the star's remaining material toward it. This material forms a spinning disk around the black hole that lasts only a few seconds. During that time, the disk ejects material outward from its poles. A jet of material moving at nearly the speed of light emits gamma rays, but slower material emits radio waves and visible light.

"Despite the differences in how much energy comes out in gamma rays, all these things seem to be caused by the same basic mechanism," said Edo Berger, a graduate student at Cal tech and lead author of the Nature paper. "Our observations now give the data that will help us understand what causes the differences. It was astounding to suddenly realize that these apparently very different cosmic beasts all are really the same thing."

The next job, Frail said, is to learn if there are, in fact, two jets, or a single jet in which the central part encounters less resistance and thus can move outward at greater speeds. Frail pointed out that the radio observations alone had the ability to show the total energy output of the burst, thus providing the breakthrough in understanding the common thread among the different types of explosions. "The key fact is that the optical, x-ray and gamma-ray telescopes missed 90% of the energy put out by this burst," Frail added. "As the VLA Expansion Project progresses and the sensitivity of the VLA improves in the coming years, it will become an even more important tool in unraveling this mystery. The exciting part of this new discovery is that explosions that we once thought were quite different now appear to all have a common origin," Frail concluded. "That insight, of course, gives us the new challenge of explaining how a single mechanism can make itself look so different."

Adapted from the press release on http://www.nrao.edu/pr/2003/grbtwinjet/.

(Added 12/06/03) Astronomers at the University of Arizona have used a new technique called "nulling interferometry" to examine a dust disk around a young, nearby star - HD 100546. Using this method, they not only confirmed that the star has a protoplanetary disk, but also discovered a gap in the disk - strong evidence for a forming planet.

"It's very exciting to find a star that we think should be forming planets, and actually see evidence of that happening," said UA astronomer Philip Hinz.

"The bottom line is, we not only confirmed the hypothesis that this young star has a protoplanetary disk, we found evidence that a giant, Jupiter-like protoplanet is forming in this disk," said Wilson Liu, a doctoral student and research assistant on the project. "There's evidence that this star is right on the cusp of becoming a main-sequence star. So basically, we're catching a star that is right at the point of becoming a main-sequence star, and it looks like it's caught in the act of forming planets."

Earlier this year, Hinz and Liu realized that observations of HD 100546 at thermal, or mid-infrared, wavelengths showed that the star had a dust disk. Finding faint dust disks is "analogous to finding a lighted flashlight next to Arizona Stadium when the lights are on," Liu said.

The nulling technique combines starlight in such a way that it is canceled out, creating a dark background where the star's image normally would be. Because HD 100546 is such a young star, its dust disk is still relatively bright, about as bright as the star itself. The nulling technique is needed to distinguish what light comes from the star, which can be suppressed, and what comes from the extended dust disk, which nulling does not suppress.

Hinz and UA astronomers Michael Meyer, Eric Mamajek, and William Hoffmann took the observations in May 2002. They used BLINC, the only working nulling interferometer in the world, along with MIRAC, a state-of-the-art mid-infrared camera, on the 6.5 m (21 ft) diameter Magellan telescope in Chile to study the roughly 10 million year-old star in the Southern Hemisphere sky.

Typically, dust in disks around stars is uniformly distributed, forming a continuous, flattened, orbiting cloud of material that is hot on the inner edge but cold most of the distance to the frigid outer edge. "The data reduction was complicated enough that we didn't realize until later that there was an inner gap in the disk," Hinz noted. "We realized the disk appeared about the same size at warmer (10 µm) wavelengths and at colder (20 µm) wavelengths. The only way that could be is if there's an inner gap."

The most likely explanation for this gap is that it is created by the gravitational field of a giant protoplanet - an object that could be several times more massive than Jupiter. The researchers believe the protoplanet may be orbiting the star at perhaps 10 A.U. The UA team is reporting the research in Astrophysical Journal Letters (ApJ Lett) and also will present a paper on the research at the American Astronomical Society meeting in Atlanta, GA, in January 2004.

Adapted from the press release on http://uanews.org/cgi-bin/WebObjects/UANews.woa/5/wa/SRStoryDetails?ArticleID=8087&wosid=Pab9mJahyGFCfQKlRpouWg.

(Added 12/06/03) NASA's Chandra X-ray Observatory has found the most distant jet ever observed in the image of a quasar over 12 billion light-years distant. The jet extends more than 100,000 light-years from the supermassive black hole that powers the quasar. Prior to this discovery, the most distant confirmed X-ray jet corresponded to a time about 3 billion years after the Big Bang.

The discovery of this jet was a surprise to the astronomers; they had previously known the distant quasar - GB1508+5714 - to be a powerful X-ray source, but there had been no indication of any complex structure or a jet. "This jet is especially significant because it allows us to probe the cosmic background radiation 1.4 billion years after the Big Bang," said Aneta Siemiginowska of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, lead author of a report on this research in the November 20^th Astrophysical Journal Letters.

A quasar is thought to be a galaxy that contains an active central supermassive black hole that his fueled by infalling gas and stars. This accretion process is often observed to be accompanied by the generation of powerful high-energy jets. As the electrons in the jet are pushed away from the quasar at near light-speed, they move through the photons from the cosmic microwave background radiation left over from an early stage of the universe's formation. When the electrons collide with the photons, the photons receive an energy boos and are moved into the x-ray band. The x-ray brightness of the jet depends on the power of the electron beam and the intensity of the background radiation.

"Everyone assumes that the background radiation will change in a predictable way with time, but it is important to have this check on the predictions," said Siemiginowska. "This jet is hopefully just the first in a large sample of these distant objects that can be used to tell us how the intensity of the cosmic microwave background changed over time."

"In fact, if this interpretation is correct, then discovery of this jet is consistent with our previous prediction that X-ray jets can be detected at arbitrarily large distances!" said team member Dan Schwartz, also of the Harvard-Smithsonian Center for Astrophysics.

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_111703.html.

(Added 12/06/03) Conventional propulsion systems use large amounts of inefficient chemical fuel to create thrust to push a spacecraft along. An experimental form of propulsion has made a leap in the development process with NASA's successful test of its new Ion Engine.

The Project Prometheus test involved a High Power Electric Propulsion (HiPEP) ion engine using commercial utility electrical power. The event marks the first in a series of performance tests to demonstrate new high-velocity and high-power thrust needed for use in nuclear electric propulsion (NEP) applications.

"The initial test went extremely well," said Dr. John Foster, the primary investigator of the HiPEP ion engine at NASA's Glenn Research Center in Cleveland, OH. "The test involved the largest microwave ion thruster ever built. The use of microwaves for ionization would enable very long-life thrusters for probing the universe."

The test was conducted in a vacuum chamber at NSAS Glen. The HiPEP ion engine was operated at power levels up to 12 KW and over an equivalent range of exhaust velocities from 60,000-80,000 meters per sec. The thruster is being designed to provide 7-10 years at high fuel efficiencies of more than 6,000-seconds specific impulse - a measure of how much thrust is generated per kg of fuel; this is a contrast to a standard chemical rocket, which has a specific impulse of about 300-400-seconds.

The HiPEP thruster operates by ionizing xenon gas with microwaves. At the rear of the engine is a pair of rectangular metal grids that are charged with 6,000 volts of electric potential. The force of this electric field exerts a strong electrostatic pull on the xenon ions, accelerating them and producing the thrust that propels the spacecraft. The rectangular shape, a departure from the cylindrical ion thrusters used before, was designed to allow for an increase in engine power and performance by means of stretching the engine. The use of microwaves should provide much longer life and ion-production capability compared to current state-of-the-art technologies.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/nov/HQ_03377_ion_engine.html.

(Added 12/06/03) Several scenarios of Martian water have emerged over the past few decades. Perhaps the most opposites are of a recent warm and wet Mars vs. an ancient wet Mars that dried up over 3 billion years ago. Still another view is that Mars has periodically experienced intense flooding in short, brief bursts.

New evidence from NASA's Mars Global Surveyor orbiter weighs in with new images of what look like deltas on Earth (see image at right). The images show what could be interpreted as eroded ancient deposits of transported sediment that hardened into interwoven, curved ridges of layered rock long ago. These have been interpreted as the paths traced by ancient rivers made in a sediment as the rivers' courses changed through time.

"Meanders are key, unequivocal evidence that some valleys on early Mars held persistent flows of water over considerable periods of time," said Dr. Michale Malin of Malin Space Science Systems, San Diego, which supplied and operates the spacecrafts' Mars Orbiter Camera. "The shape of the fan and the pattern of inverted channels in it suggest it may have been a real delta, a deposit made where a river enters a body of water. If so, it would be the strongest indicator yet Mars once had lakes."

The fan covers an area 13x11 km (8x7 miles) in the southern hemisphere. Dr. Jim Garvin, NASA's lead scientist for Mars Exploration, NASA Headquarters, Washington, states "it reaffirms we are on the right pathway for searching the record of Martian landscapes and eventually rocks for the record of habitats. Such localities may serve as key landing sites for future missions, such as the Mars Science Laboratory in 2009. These astounding findings suggest that 'following the water' with Mars Global Surveyor, Mars Odyssey, and soon with the Mars Exploration Rovers, is a powerful approach that will ultimately allow us to understand the history of habitats on the red planet"

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/nov/HQ_03364_MGS_delta.html.

(Added 11/06/03) The Hubble Heritage Team has released November's image of the Carina Nebula, AKA NGC 3372. 8,000 light-years from us, the Carina Nebula lies in the constellation Carina; this image covers approximately 1.2 arcminutes across (2.9 light-years). The image was originally taken On July 4/5, 2003, for a total exposure time of 1.6 hours.

The full expanse of the Carina Nebula is over 200 light-years - nearly 67 times the small portion shown in this month's release. The nebula - in the Southern hemisphere - is so large that it is visible with the naked eye.

The nebula is full of stars that emit high-speed winds. These energetic winds act to sculpt the the nebula into the billows, curls, and dark lanes that are seen in this image. This particular vista shows a region in the nebula between two large clusters of some of the most massive and hottest known stars, including the variable star known as Eta Carinae.

The filaments shown throughout the image are caused by turbulence in the gas, which in turn was caused by several stars shedding their outer layers. The cold interstellar gas mixed with the hot gas, leaving a veil of denser, opaque material in the foreground. The chemical elements in the surroundings create a potential reservoir for star formation. Areas in the brightest parts of the image at the top show elephant-trunk shaped dust clouds that may form into young solar systems in the future.

This image was taken as part of a parallel observing program. The HST has many instruments that can be used to look at slightly different portions of the sky at once. For this image, the Space Telescope Imaging Spectrograph was used to study Eta Carinae itself, while the Wide Field Planetary Camera 2 was used to image the nebula. The parallel observing program increases efficiency and allows astronomer to view objects that otherwise would not have been accepted by a selection committee.

Adapted from the information on http://heritage.stsci.edu/2003/31/index.html.

(Added 11/06/03) NASA's Voyager 1 spacecraft is fast becoming the first craft to enter the edge of the solar system - the heliopause - the edge of the sun's influence.

The sun emits a "solar wind" - a stream of charged particles - that rushes away and carves out a space which the solar system occupies. Where the solar wind meets the winds from other stars begins interstellar space, and it is into this region that the Voyager 1 probe will soon reach.

However, before it reaches the heliopause, Voyager 1 must pass through the termination shock; this is a violent zone that is the source of high-energy particles. Here, the solar wind rapidly slows from an average speed of 700,000-1,500,000 mph. The exact location of this volume of space is unknown because we do not know the precise conditions of interstellar space; we do, however, know the speed and pressure of solar wind changes, which causes the termination shock to expand, contract, and ripple. Its passage through the zone will give scientists the first direct measurements of the solar system's "final frontier."

"Voyager 1 has seen striking signs of the region deep in space where a giant shock wave forms, as the wind from the sun abruptly slows and presses outward against the interstellar wind. The observations surprised and puzzled us, so there is much to be discovered as it begins exploring this new region at the outer edge of the solar system," said Dr. Edward Stone, Voyager Project Scientist, California Institute of Technology, Pasadena, CA.

From about August 1, 2002, to February 5, 2003, scientists noticed unusual readings from the two energetic-particle instruments on Voyager 1, indicating it had entered a region of the solar system unlike any previously encountered. This led some to claim Voyager 1 may have entered a transitory feature of the termination shock. The controversy would be resolved if Voyager could measure the speed of the solar wind because the solar wind slows abruptly at the termination shock. However, the instrument that measured solar wind speed no longer functions on the probe. Scientists must use data from instruments still working to infer if Voyager pierced the termination shock.

"We have used an indirect technique to show the solar wind slowed down from about 700,000 mph to much less than 100,000 mph. We used this same technique when the instrument measuring the solar wind speed was still working. The agreement between the two measurements was better than 20% in most cases," Krimigis said.

"The analysis of the Voyager 1 magnetic field observations in late 2002 indicate that it did not enter a new region of the distant heliosphere by having crossed the termination shock. Rather, the magnetic field data had the characteristics to be expected based upon many years of previous observations, although the intensity of energetic particles observed is unusually high," Burlaga said.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/nov/HQ_03354_voyager_ssu.html.

(Added 10/30/03) The Sloan Digital Sky Survey, a multi-year and -national project to map 1/4 of the sky and produce a catalogue of over 100 million objects, has produced the most precise map to date of the large-scale clustering of galaxies and dark matter, refining our understanding of the structure and evolution of the universe.

The three-dimensional map contains over 200,000 galaxies up to 2 billion light-years away in over 6% of the sky. The gravitational clustering reveal the makeup of the universe from its gravitational effects.

One of the most important results from this mapping, combined with the recent measurements from the WMAP satellite, shows that the universe is made of about 70% dark energy, 25% dark matter, and 5% ordinary matter, confirming previous results.

A second result from this survey is that neutrinos cannot be a major constituent of the dark matter content of the universe. This finding ranks among the strongest constraints to date on their mass, which has yet to be measured as non-zero.

Thirdly, their results are consistent with the detailed predictions of the inflation model of the universe.

Adapted from the press release on http://www.sdss.org/news/releases/20031028.powerspectrum.html.

(Added 10/30/03) Last Thursday and Friday, the news was crawling with stories about a solar flare that had been released towards Earth and might disrupt power grids and satellites. It did not end up having too much of an effect, but just as the media was forgetting about it, a large coronal mass ejection (CME) was spotted on Monday, larger than the previous week's, and prompted more attention and warnings.

That flare was the third strongest flare seen in the last 30 years. It was classified as an X17-category, which means that it could trigger planet-wide radio blackouts and long-lasting radiation storms. And just when we thought we were out of the line of fire, yet another massive flare was spotted on Wednesday afternoon. It is a class X10 flare. The image at left is of this latter flare; the horizontal lines are caused from over-saturation of the detector on the craft used to take the image.

"It's like the Earth is looking right down the barrel of a giant gun pointed at us by the sun ... and it's taken two big shots at us," says John Kohl, a solar astrophysicist at the Harvard-Smithsonian Center for Astrophysics (CfA) and principle investigator for the Ultraviolet Chronograph Spectrometer on NASA's SOHO spacecraft (from which the image at the left was taken). "The sun is really churned up. The timing of two very large X-class flares aimed directly at the Earth, occurring one right after another, is unprecedented."

The two eruptions could create combined geomagnetic storms that could influence us in many ways. The most prominent disruptions would be in satellite communications and power grids. Steps to prevent too much damage are to put satellites in a safe mode and to lower line voltages on power grids to allow leeway for surges.

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0323.html.

(Added 10/25/03) The Mars Global Surveyor has been in orbit of Mars since September 1997. One of the experiments onboard is called TES and is used to take spectra - images that show the relative intensity of different wavelengths of light - of the planet's surface. A team headed by the U.S. Geological Survey has used TES spectra of the planet to show that Mars has likely not had liquid water on its surface for over 3 billion years.

The team used the spectra to search for the signatures of various minerals on the surface, but they were specifically interested in olivine - a green mineral that is common in many rocks. When olivine is exposed to a warm and wet environment, it becomes altered and produces secondary minerals.

An area found that was particularly rich in olivine is the Nili Fossae region, which contains an impact site - the Isidis basin - that has been dated to having formed approximately 3.6 billion years ago. The Isidis basin contains a relatively large amount (~30%) of surface olivine that the team believes was exposed very soon after the impact that created the basin. None of the secondary minerals that would have formed in a warm and wet environment were found.

There are two main explanations for this. First, if Mars had a warm and wet environment, it would have ended over 3 billion years ago. The second possible explanation is that the olivine deposits were not exposed to the surface soon after the impact, but were revealed more recently. In this case, Mars could have been cold and dry for as little as a few thousand years. Other olivine deposits in date-able areas will help constrain this.

- Stuart J. Robbins; source is: Hoefen, Todd M. et. al. "Discovery of Olivine in the Nili Fossae Region of Mars." Science 302 627 (2003).

(Added 10/16/03) On August 15, 2002, the NASA craft CONTOUR - COmet Nucleus TOUR - was destroyed. The CONTOUR Mishap Investigation Board has released their report detailing the most likely causes of the accident.

There were problems in the investigation due to lack of direct data during the accident. The craft was to remain in Earth orbit until August 15, when a solid rocket motor was fired to leave orbit and begin the craft's transit to its first cometary encounter with Encke. The design of the mission did not provide any telemetry coverage during the firing, but the craft was to establish contact with ground control after the board. No signal was received, and subsequent optical scans of the area showed three fragments where the craft should have been.

The board was able to narrow down the potential causes of the accident to a few most likely ones. The Board identified a number of possible root causes as well as observations that could result in future mission failures.

Probable Cause: "Overheating of the CONTOUR spacecraft by the solid rocket motor exhaust plume."

Alternate Causes: "Catastrophic failure of the solid rocket motor; collision with space debris or meteoroids; loss of dynamic control of the spacecraft."

Root Causes: "CONTOUR Project reliance on analysis by similarity; inadequate systems engineering process; inadequate review function."

- Stuart J. Robbins; quotes from the CONTOUR Mishap Investigation Board's final manuscript, all from page 8

(Added 10/16/03) In 1961, the former Soviet Union successfully launched Yuri Gargarin into space aboard Sputnik 11. In 1962, John Glenn was launched from the U.S. into space aboard Mercury Atlas 6. For over 40 years, these had been the only two nations to independently launch a manned probe into space. China has now become the third.

Aboard the Shenzhou (meaning "Divine Vessel") 5 spacecraft, launched atop a Long March 2F rocket at 01:00 GMT on Wednesday, October 15, 2003, from the Jiuquan launch center in China, 38-year-old Yang Liwei became the first Chinese yuhangyuan - astronaut. It was then successfully recovered after just under one day, or 14 orbits, in space. Touchdown was at 22:23 GMT on Wednesday, October 15.

The Chinese media report that the landing point was only 4.8 km (3 miles) from the target site. Yang was carried away in a seat as shown on the state television coverage of the event. Official reports from Xinhua say Yang "was confirmed to remain in good health" after his historic stay in space.

The craft apparently performed flawlessly, for no technical problems were reported nor ill effects to the occupant. Conversations with the ground control in Beijing were relayed through tracking stations and sea vessels throughout the world.

The mission lasted 21 hours, 23 minutes (liftoff to touchdown), completed 14 Earth orbits, and traveled about 600,000 km (370,000 miles). The next space launch could come as soon as a few months from now. It is unclear what it will entail, but a repeat of the Shenzhou 5 or possibly a larger crew are the most likely events.

Adapted from the information at http://spaceflightnow.com/shenzhou/031015landing.html and http://www.spacetoday.net/Summary/1963.

(Added 10/04/03) The Hubble Heritage Team has released October's image of M104, AKA the Sombrero Galaxy, AKA NGC 4594, a spiral galaxy. 28 million light-years from us, M104 lies in the constellation Virgo; this image covers approximately 10 arcminutes across (82,000 light-years). The image was originally taken in May and June of 2003, for a total exposure time of 10.2 hours.

One of the most famous and photogenic galaxies in the universe, the Sombrero is characterized by a giant blue-white core encircled by a large swath of gas. The galaxy is actually a spiral, like our own Milky Way, but it is tilted approximately 6° south of its equatorial plane. Within the bright core is a smaller disk, tilted relative to the larger disk. X-ray emissions suggest that there is material there feeding a black hole weighing approximately 1 billion times our sun.

The galaxy is just beyond naked-eye visibility, and it is easily seen through small telescopes. It is at the southern edge of the Virgo cluster and is one of the most massive objects in the group, weighing in at about 800 billion suns. The galaxy is only half as large as ours at about 50,000 light-years across.

Plainly visible even in this shrunk view of the galaxy are many of the globular clusters that belong to the Sombrero. Its globular cluster family is estimated at nearly 2000, compared with the approximate 150 known to belong to the Milky Way.

In the 19^th century, some astronomers speculated that M104 was simply an edge-on disk of luminous gas surrounding a young star, which is prototypical of the genesis of our solar system. But in 1912, astronomer V. M. Slipher discovered that the hat-like object appeared to be rushing away from us at 700 miles per second. This enormous velocity offered some of the earliest clues that the Sombrero was really another galaxy, and that the universe was expanding in all directions.

The Hubble Heritage Team took these observations with the HST's Advanced Camera for Surveys. Images were taken in three filters (red, green, and blue) to yield a natural color image. The team took six pictures of the galaxy and then stitched them together to create the final composite image. One of the largest Hubble mosaics ever assembled, this magnificent galaxy is nearly one-fifth the diameter of the full moon.

Adapted from the information on http://heritage.stsci.edu/2003/28/index.html.

(Added 10/01/03) The Hubble Space Telescope (HST) has again been used to find some of the smallest solar system bodies known, and this time they are circling about Uranus. Three objects were found -- two of them new, and one of them a rediscovery of the "lost" moon that was originally found by Voyager 2 in 1986.

The two new moons are between 12-16 km (8-10 miles) - about the size of San Francisco. They are so faint that even Voyager 2, which discovered 10 new moons of Uranus, was unable to detect them. The moons orbit closer to Uranus than its five largest satellites, and represent the first inner Uranian moons discovered from an Earth-based telescope in over 50 years.

The other discovery, or re-discovery, was of a moon named S/1986 U10, discovered in 1999 from old Voyager 2 pictures. However, follow-up observations found nothing, so it was unconfirmed for four years.

"It's a testament to how much our Earth-based instruments have improved in 20 plus years that we can now see such faint objects 1.7 billion miles [2.8 billion km] away," says Mark Showalter, a senior research associate at Stanford University in Stanford, CA, who works at the NASA Ames Research Center, in Moffett Field, CA. Showalter and Jack Lissauer, a research scientist at the NASA Ames Research Center, used HST's Advanced Camera for Surveys (ACS) to make the discovery. The images were taken August 25, 2003.

The newly discovered moons are temporarily designated as S/2003 U1 and S/2003 U2 until the IAU formally approves their discovery. S/2003 U1 is the larger of the two moons, measuring 10 miles (16 km) across. The Hubble telescope spotted this moon orbiting between the moons Puck, the largest satellite found by Voyager, and Miranda, the innermost of the five largest Uranian satellites. Astronomers previously thought this region was empty space. S/2003 U1 is 60,600 miles (97,700 km) away from Uranus, whirling around the giant planet in 22 hours and 9 minutes.

The smallest Uranian moon yet found, S/2003 U2, is 8 miles (12 km) wide. Its orbital path is just 200-450 miles (300-700 km) from the moon Belinda. S/2003 U2 is 46,400 miles (74,800 km) away from Uranus and circles the planet in 14 hours and 50 minutes. The tiny moon is part of a densely crowded field of 11 other moons, all discovered from pictures taken by the Voyager spacecraft.

"The inner swarm of 13 satellites is unlike any other system of planetary moons," says co-investigator Jack Lissauer. "The larger moons must be gravitationally perturbing the smaller moons. The region is so crowded that these moons could be gravitationally unstable. So, we are trying to understand how the moons can coexist with each other."

One idea is that some of the moons are young and formed through collisions with wayward comets. For example, the Hubble telescope spotted two small moons orbiting very close to the moon Belinda. One of them is the newly detected moon, S/2003 U2, which is traveling inside Belinda's orbit. The other, designated S/1986 U10, was found in 1999 by astronomer Erich Karkoschka of the University of Arizona, who uncovered the satellite in Voyager pictures. But the finding required confirmation by an Earth-based telescope. This is the first time this moon has been seen since Voyager snapped a picture of it. S/1986 U 10 is 750 miles (1,200 km) away from Belinda.

The astronomers hope to refine the orbits of the newly discovered moons with further observations. "The orbits will show how the moons interact with one another, perhaps showing how such a crowded system of satellites can be stabilized," Showalter explains. "This could provide further insight into how the moon system formed. Refining their orbits also could reveal whether these moons have any special role in confining or 'shepherding' Uranus's 10 narrow rings."

Astronomers stretched the limit of Hubble's ACS to find the tiny satellites. "These moons are 40 million times fainter than Uranus," Showalter says. "The moons are at 25^th magnitude and Uranus is at 6^th magnitude. They are blacker than asphalt, if their composition is like the other small, inner moons. So they don't reflect much light. Even with the sensitivity and high resolution of Hubble's ACS, we had to overexpose the images of Uranus to pinpoint the moons."

The newly detected moons, when approved by the IAU, will bring the Uranian satellite total to 24. Uranus ranks third in the number of IAU-certified moons behind Jupiter (38) and Saturn (30). Excluding the outer moons that travel in elongated orbits and are probably captured asteroids, Uranus holds the record for the most satellites with 18 in its inner system. All of them have nearly circular orbits. Saturn is second with 17.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/29/.

(Added 10/01/03) SMART-1, Europe's first science spacecraft sent to orbit Earth's moon, was launched at 23:14 GMT on September 27, 2003, aboard Ariane Flight 162, launched from the Guiana Space Centre in Kourou, French Guiana. It achieved its initial Earth orbit within the next hour.

The 368 kg (811 lb) craft is now beginning its long, 18-month journey to Earth's closest celestial neighbor, to enter into a lunar orbit in March 2005. "Science and technology go hand in hand in this exciting mission to the moon. The Earth and Moon have over 4 thousand million years of shared history, so knowing the moon better will help scientists in Europe and all over the world to better understand our planet and will give them valuable new hints on how to better safeguard it," said ESA Director of Science David Southwood, following the launch from Kourou.

As the first mission in the new series of Small Missions for Advanced Research in Technology, SMART-1 is mainly designed to demonstrate innovative and key technologies for future deep space science missions. The first technology to be demonstrated on SMART-1 will be Solar Electric Primary Propulsion (SEPP), a highly efficient and lightweight propulsion system that is ideal for long-duration deep space missions in and beyond our solar system. SMART-1's propulsion system consists in a single ion engine fueled by 82 kg (181 lb) of xenon gas and pure solar energy. This plasma thruster relies on the "Hall Effect" to accelerate xenon ions to speed up to 16,000 km/hour (10,000 mph). It is able to deliver 70 mN of thrust with a specific impulse (the ratio between thrust and propellant consumption) 5 to 10 times better than traditional chemical thrusters and for much longer durations (months or even years, compared to the few minutes' operating times typical of traditional chemical engines).

The ion engine was scheduled to go into action on September 30. At first, it will fire almost continuously - stopping only when the spacecraft is in the Earth's shadow - to raise the altitude of its perigee (the lowest point of its orbit) from 750 to 20,000 km (450 to 12,500 miles). This maneuver will take about 80 days to complete and will place the spacecraft safely above the radiation belts that surround the Earth.

Once at a safe distance from Earth, SMART-1 will fire its thruster for periods of several days to progressively raise its apogee (the maximum altitude of its orbit) to the orbit of the moon. At 200,000 km (125,000 miles) from Earth, it will begin receiving significant tugs from the moon as it passes by. It will then perform three gravity-assist maneuvers while flying by the moon in late December 2004, late January and February 2005. Eventually, SMART-1 will be "captured" and enter a near-polar elliptical lunar orbit in March 2005. SMART-1 will then use its thruster to reduce the altitude and eccentricity of this orbit.

During this 18-month transfer phase, the solar-electric primary propulsion's performance, and its interactions with the spacecraft and its environment, will be closely monitored by the Spacecraft Potential, Electron & Dust Experiment (SPEDE) and the Electric Propulsion Diagnostic Package (EPDP) to detect possible side-effects or interactions with natural electric and magnetic phenomena in nearby space. A promising technology, Solar Electric Primary Propulsion could be applied to numerous interplanetary missions in the solar system, reducing the size and cost of propulsion systems while increasing maneuvering flexibility and the mass available for scientific instrumentation.

In addition to Solar Electric Primary Propulsion, SMART-1 will demonstrate a wide range of new technologies like a Li-Ion modular battery package; new-generation high-data-rate deep space communications in X and Ka bands with the X/Ka-band Telemetry and Telecommand Experiment (KaTE); and a computer technique enabling spacecraft to determine their position autonomously in space, which is the first step towards fully autonomous spacecraft navigation.

Despite its relatively small budget and short development schedule, SMART-1 holds tremendous potential for future missions and is a clear illustration of Europe's ambitions in the exploration of the solar system, also highlighted by June's launch of Mars Express, which has now completed over the half on its journey to Mars, and the launch of Rosetta, due in February 2004, to visit comet Churyumov-Gerasimenko.

Adapted from the press release on http://www.esa.int/export/esaCP/Pr_60_2003_p_EN.html.

(Added 09/17/03) X-rays may have a new calling - to reveal whether or not a black hole is spinning. Tell-tale x-ray emissions from iron could be used by the NASA Chandra X-ray Observatory and the European Space Agency's XMM-Newton Observatory to make this determination.

During a press conference at the "Four Years of Chandra" symposium in Huntsville, AL, Jon Miller of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, discussed recent results on the x-ray spectra of iron atoms in the gas around three stellar-sized black holes in the Milky Way.

"The latest work provides the most precise measurements yet of the x-ray spectra for stellar black holes. These data help rule out competing explanations that do not require extreme gravitational effects, and provide the best look yet at the geometry of the space-time around a stellar black hole created by the death of a massive star."

The orbit of a particle near a black hole depends on the curvature of space around the black hole, which also depends on how fast the black hole is spinning. A spinning black hole drags space around with it and allows atoms to orbit closer to the black hole than is possible for a non-spinning black hole. The latest Chandra data from Cygnus X-1, the first stellar-size black hole discovered, show that the gravitational effects on the signal from the iron atoms can only be due to relativistic effects, and that some of the atoms are no closer than 100 miles to the black hole. There was no evidence that the Cygnus X-1 black hole is spinning.

The XMM-Newton data from the black hole XTE J1650-500 show a very similar distribution of iron atom x-rays with one important exception. More low energy x-rays from iron atoms are observed, an indication that some x-rays are coming from deep in the gravitational well around the black hole, as close as 20 miles to the black hole event horizon. This black hole must be spinning rapidly.

Chandra observations of a third stellar black hole, GX 339-4, have revealed that it is also spinning rapidly, and clouds of warm absorbing gas appear to be flowing away from the black hole at speeds of about three hundred thousand miles per hour. Such warm gas flows have been observed in the vicinity of supermassive black holes.

One possibility as to why some black holes spin and others don't is that differences in spin are imparted at birth when a massive star collapses. Another possibility is that the spin rate depends on how long the black hole has been devouring matter from its companion star, a process that makes the black hole spin faster. Black holes with more rapid spin, XTE J1650-500 and GX 339-4, have low-mass companion stars. These relatively long-lived stars may have been feeding the black hole for longer, allowing it to spin up to faster rates. Cygnus X-1 with its short-lived companion star may not have not time to spin up.

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_091703.html.

(Added 09/17/03) Our closest celestial neighbor, the moon, has been the recent target of NASA's Chandra X-ray Observatory. The Observatory has been able to detect abundances and distributions of such elements as oxygen, magnesium, aluminum, and silicon over a large area of the moon. Such data can help determine how the moon was formed.

"We see x-rays from these elements directly, independent of assumptions about the mineralogy and other complications," said Jeremy Drake of the Harvard-Smithsonian Center for Astrophysics in Cambridge, MA, at a press conference at the "Four Years with Chandra" symposium in Huntsville, AL. "Remote sensing with Chandra can cover a much wider area" than the samples from the six widely-spaced Apollo landing sites.

The x-rays that Chandra detects from the moon are caused by fluorescence - a process whereby solar x-rays hit the lunar surface, knock electrons into high energy states, and cause other electrons to fill the vacant gaps, converting their energy in to the energy detected by the Observatory.

The data have also served to solve a mystery about the x-rays from Luna's dark side. Data from the German ROSAT satellite in 1990 showed x-rays from the dark side. They were attributed to energetic electrons streaming from the sun and hitting the lunar surface. Chandra's observations of the x-ray's energies have shown that the x-rays actually only appear to come from the moon; they are emitted by Earth's extended outer atmosphere, through which both ROSAT and Chandra would move.

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_091603.html.

(Added 09/10/03) In March of 2003, Saturn reached its maximum tilt of 27° as seen from Earth. This happens once in its orbit - every 29.5 years. NASA's Hubble Space Telescope (HST) used this opportunity to take detailed images in different wavelengths of the southern hemisphere and the southern face of its rings.

The images are, top to bottom, ultraviolet, visual, and infrared. The HST's Wide Field Planetary Camera 2 used 30 different filters to take the images on March 7. "The set of 30 selected filters may be the best spectral coverage of Saturn observations ever obtained," says planetary researcher Erich Karkoschka of the University of Arizona. The different wavelengths allow different features of Saturn to come into view. Only by studying the different wavelengths in a manner such as this can researchers interpret the data and better understand the planet.

Through studying the hazes and clouds in these images, researchers can learn about the dynamics of Saturn's atmosphere. These images reveal the properties and sizes of aerosols in Saturn's gaseous atmosphere. For example, smaller aerosols are visible only in the ultraviolet image because they do not scatter or absorb visible or infrared light, which have longer wavelengths.

By determining the characteristics of the atmosphere's constituents, researchers can describe the dynamics of cloud formation. At certain visible and infrared wavelengths, light absorption by methane gas blocks all but the uppermost layers of Saturn's atmosphere, which helps researchers discern clouds at different altitudes. In addition, when compared with images of Saturn from seasons past (1991 and 1995), this view of the planet also offers scientists a better comprehension of Saturn's seasonal changes.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/23/.

(Added 09/10/03) The ESA's Rosetta mission, plagued with delays, has recently received help from NASA's Hubble Space Telescope (HST). HST has found the craft a new target for its mission - to land on a comet and study its origin - 67P/Churyumov-Gerasimenko (67P/C-G).

Hubble was used to precisely measure the size, shape, and rotational period of the comet. It is approximately 3x2 miles - football-shaped - different than the 6 km (3.6 miles) nucleus that mission scientists had thought. "Although 67P/C-G is roughly three times larger than the original Rosetta target, its elongated shape should make landing on its nucleus feasible, now that measures are in place to adapt the lander package to the new configuration before next year's launch," says Dr. Philippe Lamy of the Laboratoire d'Astronomie Spatiale in France. Other data determined about the comet include its rotation period of approximately 12 hours.

Once it was realized that the delays in the Rosetta mission would make a rendezvous with comet 46P/Wirtanen impossible, new targets were sought. Once a list was created, mission scientists sought data from the world's largest and best telescopes to find more information about the target comets. 61 images of 67P/C-G were taken over 21 hours between March 11-12, 2003.

Rosetta is set to launch in February 2004 with a rendezvous with the comet about 10 years later.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/26/.

(Added 09/10/03) Beyond the orbit of Neptune and through Pluto's realm lies a vast sea of comets and asteroids, collectively called the Kuiper Belt, left over from the solar system's creation. Until 1992, this cloud was only theorized to exist, but in that year the first Kuiper Belt Object (KBO) was found.

Now, astronomers have used the Hubble Space Telescope (HST) to discover the three faintest and smallest - roughly the size of Philadelphia - KBO's found to date. The only big surprise was how few KBO's were found.

With the resolution afforded by HST, the team expected to find at least 60 KBO's, some as small as 15 km (10 miles) in diameter. "Discovering many fewer Kuiper Belt Objects than was predicted makes it difficult to understand how so many comets appear near Earth, since many comets are thought to originate in the Kuiper Belt," says Gary Bernstein of the University of Pennsylvania at a meeting of the Division of Planetary Sciences in Monterey, CA. "This is a sign that perhaps the smaller planetesimals have been shattered into dust by colliding with each other over the past few billion years."

The HST Advanced Camera for Surveys was pointed at a region in the constellation Virgo over a 15-day period in January and February 2003. 10 computers worked for six months searching for fast-moving spots in the Hubble images - the tell-tale sign of a solar system object. 2003 BF91, 2003 BG91, and 2003 BH91 were the three object found, and they range in size from 25-45 km (15-28 miles) in diameter. They are a billion time fainter (29th magnitude) than the dimmest objects visible to the naked eye at their current distance.

The interest in finding KBO's lies in their primordial makeup; they are thought to be the undisturbed remains of the material that formed the solar system - 4-5 billion-year-old fossils of the original building blocks of the solar system. Current theories hold that the planets and moons formed from the blocks - called planetesimals - and their gravity later ejected the left over material from the solar system or to its outer reaches. If The HST could search the entire sky, it would find about 500,000 planetesimals. that would collectively form a body a few times larger than Pluto.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/25/; preliminary results are available at http://arxiv.org/abs/astro-ph/0308467.

(Added 09/10/03) The Space Infrared Telescope Facility (SIRTIF), launched from Cape Canaveral, FL, on August 25, has switched on two of its onboard instruments to take preliminary images of stars.

The images were taken as part of a test of the infrared array camera. A full month is still needed to fully focus and fine-tune the telescope, as well as to cool it to optimal operating temperature. Therefore, these images are tantalizing treats of what's in store once the optics can be used to their full potential.

"We're extremely pleased, because these first images have exceeded out expectations," said Dr. Michael Warner, the SIRTIF project scientist at NASA's Jet Propulsion Laboratory in Pasadena, CA.

The dust cover was ejected on August 29 and the aperture door opened on August 30. All systems are operating normally. In addition to the infrared array camera, the multi=band imaging photometer instrument has also been successfully tested. The pointing calibration and reference sensor detected light from a star cluster. The third instrument - an infrared spectrograph - will be turned on later this month.

The current in-orbit checkout is scheduled to last two months, and it will be followed by a one-month science verification phase. After that, the telescope will begin its formal operation for scientific discoveries.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/sep/HQ_03282_infrared_telescop.html.

(Added 09/10/03) For the first time, sound waves have been detected from a supermassive black hole. NASA's Chandra X-ray Observatory was able to spot this "note" - a B flat - and it is the deepest pitch ever detected by an object in the universe. The energy carried by these sound waves may now help to solve a longstanding problem in astrophysics.

The black hole lies in the Perseus cluster, 250 million light-years away. Chandra was used in 2002 to view ripples in the gas filling the cluster - evidence for sound waves that have traveled hundreds of thousands of light-years from the cluster's central black hole.

The B flat note is 57 octaves below middle C. It's frequency is over a million billion times deeper than the limits of human hearing; however, "these sound waves may be the key in figuring out how galaxy clusters, the largest structures in the universe, grow," said Steve Allen of the Institute of Astronomy in Cambridge, England, a co-investigator in the study.

For years, astronomers have tried to understand why there is so much hot gas in galaxy clusters and so little cool gas. Hot gas should be cool and the dense, central gas should cool the fastest. The pressure in the cool central gas should fall, causing gas further out to sing towards the galaxy, forming trillions of stars along the way. Very little evidence has been found of such events, forcing astronomers to invent different ways to explain why the gas remained hot.

A popular mechanism was heating by a central black hole. Jets had been observed at radio wavelengths, but their effect was unclear since the gas is visible only in x-rays. Cavities had previously been found around the central Perseus cluster black hole, but the mechanism for forming them and then heating the surrounding gas was unknown. The sound waves found by Chandra could provide the mechanism.

The combined energy from 100 million supernovae is required to generate the cavities. Energy carried by the sound waves should dissipate in the cluster gas, keeping it warm and preventing cool flow. If so, the B flat would have remained roughly constant for about 2.5 billion years - a cosmic tuner.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/sep/HQ_03284_Chandra_Hears.html.

(Added 09/09/03) The Hubble Heritage Team has released September's image of NGC 3370, a spiral galaxy. 8200 light-years from us, NGC 3370 lies in the constellation Leo; this image covers approximately 3.4 arcminutes across (98,000,000 light-years). The image was originally taken in April and May of 2003, for a total exposure time of 25 hours.

Nearly ten years ago, this galaxy hosted a bright exploding star. In November of 1994, the supernova's light reached Earth, briefly outshining the billions of other stars in this galaxy.

Supernovae are common, occurring once every few seconds somewhere in the universe, but this one was special. Named SN 1994ae, it was one of the nearest and best observed since the advent of modern, digital detectors. It also is a type Ia supernova, meaning that astronomers have a standard model for how they occur, and thus how bright they really are, so the distances to them can be accurately determined.

The more type Ia supernovae that are observed, the more the extragalactic distance scale can be refined. The importance of nearby supernovae is to correctly calibrate the scale with a closer measurement stick - cepheid variable stars. Cepheid variables are used to determine distances to more nearby objects than supernovae because cepheids are far dimmer than the stellar explosions. However, if one can observe both cepheids and a type Ia supernova in the same galaxy, then the two scales can be tested and calibrated.

That is where the Hubble Space Telescope comes into play. Its new Advanced Camera for Surveys has the ability to resolve individual cepheids within NGC 3370. Observed twelve times over a month, many of these stars have been found in the galaxy - the most distant cepheids yet observed.

Adapted from the information on http://heritage.stsci.edu/2003/24/index.html.

(Added 08/31/03) On August 26, the independent Columbia Accident Investigation Board released a 248-page report detailing the Board's findings as to the nature and cause of the accident that occurred on February 1, 2003, resulting in the destruction of the Space Shuttle Columbia and the seven astronauts who were aboard.

STS-107 Patch The astronauts aboard were Rick D. Husband - Commander, William C. McCool - Pilot, Michael P. Anderson - Payload Commander, David M. Brown - Mission Specialist, Kapana Chawla - Mission Specialist, Laurel Blair Salton Clark - Mission Specialist, and Ilan Ramon - Payload Specialist and the first Israeli in space. The original mission patch appears to the left.

The Board determined the physical cause of the tragedy as well as organizational causes; it also posed recommendations for NASA that will help prevent future accidents from occurring.

"The physical cause of the loss of Columbia and its crew was a breach of the Thermal Protection System on the leading edge of the left wing, caused by a piece of insulating foam which separated from the left ... section of the External tank 81.7 seconds after launch, and struck the wing ... . During re-entry this breach in the Thermal Protection System allowed superheated air to penetrate through the leading edge insulation and progressively melt the aluminum structure of the left wing, resulting in a weakening of the structure until increasing aerodynamic forces caused loss of control, failure of the wing, and breakup of the Orbiter. This breakup occurred [in a manner that], given the current design of the Orbiter, there was no possibility for the crew to survive." - page 9
"The organizational causes of this accident are rooted in the Space Shuttle Program's history and culture, including the original compromises that were required to gain approval for the Shuttle, subsequent years of resource constraints, fluctuating priorities, schedule pressures, mischaracterization of the Shuttle as operational rather than developmental, and lack of an agreed national vision for human space flight. ... [O]rganizational practices detrimental to safety were allowed to develop, including: reliance on past success as a substitute for sound engineering practices (such as testing to understand why systems were not performing in accordance with requirements); organizational barriers that prevented effective communication of critical safety information and stifled professional differences of opinion; lack of integrated management across program elements; and the evolution of an informal chain of command and decision-making processes that operated outside the organization's rules." - page 9
The recommendations for the future include physical changes to the shuttle program, including "preventing the loss of [protective] foam, improved imaging of the Space Shuttle stack from liftoff through separation of the External Tank, and on-orbit inspection and repair of the Thermal Protection System." - page 9

- Stuart J. Robbins; quotes from the Columbia Accident Investigation Board's final manuscript

(Added 08/07/03) The Hubble Heritage Team has released August's image of NGC 6397, a globular cluster. 8200 light-years from us, NGC 6397 lies in the constellation Ara; this image covers approximately 2 arcminutes across (3.8 light-years). The image was originally taken March 6-7, 1996, April 3-4, 1999, and November 4, 2001, for a total exposure time of 7 hours.

In this, one of the nearest globular clusters, the stellar density is about a million times larger than our local volume of space; the stars are a few light-weeks apart, whereas the closest star to the sun is over four light-years away. Estimated to be over 12 billion years, old, thousands of stellar collisions have occurred in the cluster's lifetime.

The purpose of the images that were composited to make this vista was to study what is left behind from the star collisions - the "blue stragglers." Blue stragglers are so-called because of their bright blue color, which is normally characteristic of very young stars. However, due to the enormous age of the cluster, the cluster should have stopped making stars long ago, so there should not be any blue stars. Hence the term "straggler."

These can be theoretically formed in one of two ways. First, two stars collide. Their combined mass and the convection caused by the collision results in a larger star that glows hot enough to be blue. The second way is that if there is a near-miss, some material may be transferred from one of the stars to the other, and the result will be the same as in the previous model. If the two stars do not collide but end up forming a binary system, a cataclysmic variable star could result. The program was specifically looking for the cataclysmic variable stars.

To search for these, 55 images were taken over a period of about 20 hours. Most were taken in ultraviolet (UV) and blue filters, but some were in green and infrared (IR). Comparing the brightness of all the stars in the images, the astronomers were able to identify several cataclysmic variable stars in the cluster. A few of them are visible in the Hubble Heritage image as faint blue or violet stars.

An unexpected result is from three faint blue stars near the center of the cluster (turquoise in the image). These don't vary in brightness, and they are not cataclysmic variables. They may be very low-mass white dwarfs, formed in the cores of giant stars whose evolution was interrupted before a full-fledged white dwarf was formed. Such an interruption could occur as the result of a collision or interaction. When the giant star interacts with another star, it can lose its outer layers, exposing its hot, blue core. The end result will be a white dwarf of a smaller mass than would have otherwise evolved.

A large number of normal white dwarfs were also identified and studied. These stars appear throughout the cluster since they form through normal stellar evolution processes and don't involve any stellar interactions, which occur predominantly near the cluster center. Nearly 100 such burned-out stars were identified in these images, the brightest of which can be seen here as faint blue stars.

Adapted from the information on http://heritage.stsci.edu/2003/21/index.html.

(Added 07/20/03) As the ESA's Mars Express continues on its voyage to Mars, one of the first data sets to come back is a unique picture of Earth and Moon. "It is very good news for the mission," says ESA's Mars Express Project Scientist, Agustin Chicarro. These and other data, such as spectra of Earth, are proof that the instruments on Mars Express are working perfectly.

Earth and Moon from Mars Express The routine check-outs of Mars Express' instruments and the Beagle-2 lander over the last few weeks have been very successful.

The images of Earth and Moon were taken on July 3, 2003, by Mars Express High Resolution Stereo Camera (HRSC), when the craft was 8 million km (5 million miles) from Earth. The image is in true color, showing the Pacific Ocean and clouds.

Testing will continue on the instruments up until the arrival to Mars, this December. The instruments will enormously increase our understanding of the morphology and topography of the Martian surface, past and present geological structures and processes, and eventually of Mars' geological evolution.

Adapted from the press release on http://www.esa.int/export/esaCP/SEMTNOXO4HD_index_0.html.

(Added 07/20/03) A group of German and U.S. astronomers has been able to show the growth of supermassive black holes is closely linked with the birth of new stars in their host galaxies. The group made this discovery - the first direct evidence of a connection - by studying over 120,000 nearby galaxies observed as part of the Sloan Digital Sky Survey. The journal paper accompanying this is entitled The Host Galaxies of the Active Galactic Nuclei and was submitted to the Monthly Notices of the Royal Astronomical Society.

The main question in recent years since the discovery that every large galaxy contains a central supermassive black hole has been whether the black hole controls the growth of the host, or if the host controls the growth of the black hole.

By studying the spectra of more than 120,000 galaxies, the team was able to show that more than 20,000 of them contain black holes that are currently growing. These are located almost exclusively in galaxies more massive than the Milky Way. The rate of growth is inferred from the strength of characteristic emission lines known to be correlated with how much material is falling into the black hole.

The team was able to conclude that as the rate of black hole growth increases, so does the amount of star formation within the past 100 million years. In the most extreme cases, the black hole is growing as fast as in bright quasars and the galaxy is dominated by young stars.

This probably means that the black hole is growing by swallowing some of the supply of gas from which the stars are forming elsewhere in the galaxy. The stellar mass of the galaxies and the masses of their black holes are growing together, each necessary for the other.

Adapted from the press release on http://www.sdss.org/news/releases/20030715.blackhole.html.

(Added 07/10/03) In one of the Milky Way's ancient globular clusters, there lies a star system consisting of a pulsar and a white dwarf trapped as a binary system. And orbiting this pair, the Hubble Space Telescope has confirmed the existence of the oldest known planet - extrasolar or otherwise - in existence.

The planet is approximately 2.5 times Jupiter's mass, and it takes about 100 years to make one complete orbit about its stars. The most amazing property of it, however, is that its age is 13 billion years. This planet had formed when the universe was less than 7% its current age.

The globular cluster in which the system resides, M4, is approximately 5,600 light-years away in the constellation Scorpius. Previous thinking had been that globular clusters, old and so devoid of heavy metals which had seemed necessary for planet-making, would not contain planets. This reasoning had been reinforced by the finding in 1999 of no "hot Jupiters" in the cluster 47 Tucanae. This newest finding contradicts previous reasoning, leaving the door wide open for planets to be found in great abundance in globular clusters.

The pulsar, PSR B1620-26, was discovered in 1988, and spins at just under 100 times per second. The white dwarf was found quickly through its effects on the pulsar, and they orbit each other twice per year. Further irregularities in the pulsar implied a third object orbiting the stars, and the suspect was a planet, brown dwarf, or low-mass star.

The debate has finally been settled by measuring the planet's actual mass. Hubble data from the mid-1990's that was taken to study white dwarfs in M4 was examined, and the team was able to measure the color and temperature of the dwarf in the system. Evolutionary models were then used to compute the dwarf's mass. The true mass lead to the system's inclination relative to Earth, and combined with radio studies of the pulsar, the planet's tilt could be determined, leading to the exact mass. At 2.5 Jupiters, it is a planet.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/jul/HQ_03234_Oldest_Planet.html.

(Added 07/08/03) After two days of rain delay, the first of two rovers in NASA's Mars Exploration Rover (MER) mission launched from Cape Canaveral Air Force Station, FL, on July 7, 2003. The rover is on a seven-month mission to the red planet where it will land on January 25, 2004 (UT).

Lift-off occurred aboard a Delta II launch vehicle at 23:18:15 EDT. The probe separated from the Delta II's third stage about 83 minutes after the launch, and was heard from at 00:23 EDT by the Goldstone, CA , ground-based tracking station. The rover had originally been scheduled to be launched on June 28, but poor weather conditions held back the initial launch, and the discovery of insulation de-bonding further delayed it. The second of the twin rovers in the MER project, this one is named "Opportunity."

- Stuart J. Robbins

(Added 07/04/03) The Hubble Heritage Team has released July's image of LMC N 49, AKA DEM L 190, a supernova remnant. 160,000 light-years from us, the LMC N 49 lies in the constellation Dorado; this image covers approximately 1.9 arcminutes across (0.91 light-years). The image was originally taken November 14, 1998, April 27, 1999, and July 14, 2000, for a total exposure time of 3.1 hours.

The wisps that form this celestial object resembling many colors of cotton candy are the remains of a supernova that erupted thousands of years ago in the small, neighboring galaxy the Large Magellanic Cloud (LMC). The debris will eventually be recycled into other stars.

Besides the filaments and streamers that make up this nebula, there exists a very powerful pulsar within the nebula that may be the remnant from the initial explosion. The pulsar frequency is 1/8 Hz, pulsing once every eight seconds. This pulsar is also classified as a "magnetar" due to its very strong magnetic field - 10¹⁵ times stronger than Earth's.

This pulsar is also responsible for a historic gamma-ray burst that occurred on March 5, 1979, and was detected by several satellites. Since then, N 49 has had several subsequent gamma-ray emissions, and is now recognized as a "soft gamma-ray repeater," releasing lower-energy gamma-rays than most gamma-ray bursters.

Today, N 49 is the target of investigations led by Hubble astronomers You-Hua Chu from the University of Illinois at Urbana-Champaign and Rosa Williams from the University of Massachusetts. Members of this science team are interested in understanding whether small cloudlets in the interstellar medium of the LMC may have a marked effect on the physical structure and evolution of this supernova remnant.

This image of N 49 is a color representation of data taken in July 2000, with Hubble's Wide Field Planetary Camera 2. Color filters were used to sample light emitted by sulfur ([S II]), oxygen ([O III]), and hydrogen (H-α). The color image has been superimposed on a black and white image of stars in the same field also taken with the HST.

Adapted from the information on http://heritage.stsci.edu/2003/20/index.html.

(Added 07/04/03) Astronomers have observed a young star ringed by a swirling disc that may spin off planets, marking the first published science observation using two linked 10-meter (33-foot) telescopes in Hawaii. The linked telescopes at the W.M. Keck Observatory on Mauna Kea, known as the Keck Interferometer, comprise the world's largest optical telescope system.

The observation was made of DG Tau, a young star that has not yet begun to burn hydrogen in its core. Such stars are called T-Tauri objects. Observations of DG Tau were made on October 23, 2002, and February 13, 2003, and the findings will appear in an upcoming issue of the Astrophysical Journal Letters.

"We're trying to measure the size of the hot material in the dust disc around DG Tau, where planets may form," said Dr. Rachel Akeson, leader of the study team and an astronomer at the Michelson Science Center at the California Institute of Technology in Pasadena. "Studies like this teach us more about how stars form, either alone or in pairs, and how planets eventually form in discs around stars."

The Keck Interferometer observations revealed a gap of 18 million miles between DG Tau and its orbiting dust disc. Akeson notes that of the extra-solar planets discovered so far, roughly one in four lies within 10 million miles of the parent star. Since planets are believed to form within a dust disc, either DG Tau's disc has a larger-than-usual gap, or the close-in planets form farther from the star and migrate inward.

Since 1995, astronomers have detected more than 100 extra-solar planets, many considered too large and close to their hot, parent stars to sustain life. By measuring the amount of dust around other stars, where planets may form, the Keck Interferometer will pave the way for NASA's Terrestrial Planet Finder mission. Terrestrial Planet Finder will look for smaller, Earth-like planets that may harbor life. The Keck Interferometer and Terrestrial Planet Finder are part of NASA's Origins Program.

"T-Tauri objects had been observed with other instruments, but only the brightest ones were detectable until now," Akeson said. "With the larger telescopes and greater sensitivity of the Keck Interferometer, we can look at fainter T-Tauri objects, like this one." The Keck Interferometer gathers light waves with two telescopes and then combines the waves so they interact, or "interfere" with each other. It's like throwing a rock into a lake and watching the ripples, or waves, and then throwing in a second rock. The second set of waves either bumps against the first set and changes its pattern, or both sets join together to form larger, more powerful waves. With interferometry, the idea is to combine light waves from multiple telescopes to simulate a much larger, more powerful telescope.

In its ability to resolve fine details, the Keck Interferometer is equivalent to an 85-meter (279-foot) telescope. "The system transports the light gathered by the two telescopes to an optical laboratory located in the central building," said Dr. Mark Colavita of NASA's Jet Propulsion Laboratory (JPL), Pasadena, interferometer system architect and lead author of the paper. "In the lab, a beam combiner and infrared camera combine and process the collected light to make the science measurement." To make these measurements, the interferometer's optical system adjusts the light paths to a fraction of a wavelength of light, and adaptive optics on the telescopes remove the distortion caused by Earth's atmosphere.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/jul/HQ_03223_telescope.html.

(Added 07/04/03) Nearly 100 years after Albert Einstein's formulation of Relativity, scientists are still finding new applications for it. One of the many predictions of relativity is gravitational waves - ripples in the fabric of space-time that are produced by very massive bodies. A new application of gravitational waves is to place a "speed limit" on the spin of pulsars, according to a report published in the July 3 issue of Nature.

Pulsars have been observed with spin rates as low as about one revolution per millisecond - almost 20% light speed. These pulsars would fly apart if they spun too much faster.

With NASA's Rossi X-ray Timing Explorer, scientists have found a limit as to how fast a pulsar can spin and speculate the cause to be gravitational radiation. The faster a pulsar spins, the more gravitational radiation it would release, and its spherical body would become deformed. This may restrain the pulsar's rotation and save it from self-destruction.

"Nature has set a speed limit for pulsar spins," said Prof. Deepto Chakrabarty of the Massachusetts Institute of Technology (MIT) in Cambridge, lead author on the journal article. "Just like cars speeding on a highway, the fastest-spinning pulsars could technically go twice as fast, but something stops them before they break apart. It may be gravitational radiation that prevents pulsars from destroying themselves." Chakrabarty's co-authors are Drs. Edward Morgan, Michael Muno, and Duncan Galloway of MIT; Rudy Wijnands, University of St. Andrews, Scotland; Michiel van der Klis, University of Amsterdam; and Craig Markwardt, NASA Goddard Space Flight Center, Greenbelt, Md. Wijnands also leads a second Nature letter complementing this finding.

Millisecond pulsars can form if a dense pulsar, with its strong gravitational potential, is in a binary system. In this situation, it can pull material from its companion star to itself. This influx can spin up the pulsar to the millisecond range, rotating hundreds of times per second. In some pulsars, the accumulating material on the surface occasionally is consumed in a massive thermonuclear explosion, emitting a burst of X-ray light lasting only a few seconds. In this fury lies a brief opportunity to measure the spin of otherwise faint pulsars. Scientists report in Nature that a type of flickering found in these X-ray bursts, called "burst oscillations," serves as a direct measure of the pulsars' spin rate. Studying the burst oscillations from 11 pulsars, they found none spinning faster than 619 times per second.

The Rossi Explorer is capable of detecting pulsars spinning as fast as 4,000 times per second. Pulsar breakup is predicted to occur at 1,000 to 3,000 revolutions per second. Yet scientists have found none that fast. From statistical analysis of 11 pulsars, they concluded that the maximum speed seen in nature must be below 760 revolutions per second.

This observation supports the theory of a feedback mechanism involving gravitational radiation limiting pulsar speeds, proposed by Prof. Lars Bildsten of the University of California, Santa Barbara. As the pulsar picks up speed through accretion, any slight distortion in the star's dense, half-mile-thick crust of crystalline metal will allow the pulsar to radiate gravitational waves. An equilibrium rotation rate is eventually reached where the angular momentum shed by emitting gravitational radiation matches the angular momentum being added to the pulsar by its companion star.

Bildsten said that accreting millisecond pulsars could eventually be studied in greater detail in an entirely new way, through the direct detection of their gravitational radiation. LIGO, the Laser Interferometer Gravitational-Wave Observatory now in operation in Hanford, Wash. and in Livingston, LA, will eventually be tunable to the frequency at which millisecond pulsars are expected to emit gravitational waves. "The waves are subtle, altering space-time and the distance between objects as far apart as the Earth and the moon by much less than the width of an atom," said Prof. Barry Barish, LIGO director from the California Institute of Technology, Pasadena. "As such, gravitational radiation has not been directly detected yet. We hope to change that soon."

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/jul/HQ_03224_Pulsar_Spin.html.

(Added 06/26/03) NASA's 2001 Mars Odyssey craft is revealing new details about the dynamics of frozen layers in the high northern latitudes of Mars. The implications have bearing on science strategies for future missions in the search of habitats.

Odyssey's neutron and gamma ray sensors tracked seasonal changes as layers of dry ice accumulated during the northern hemisphere's winter and then dissipated in the spring, exposing the martian permafrost. Researchers used measurements of martian neutrons, combined with height measurements from the laser altimeter on the Mars Global Surveyor, to monitor the amount of dry ice during the northern winter and spring seasons.

"Once the carbon-dioxide layer disappears, we see even more water ice in northern latitudes than Odyssey found last year in southern latitudes," said Odyssey's Dr. Igor Mitrofanov of the Russian Space Research Institute, Moscow, lead author of a paper in the June 27 issue of the journal Science. "In some places, the water ice content is more than 90 percent by volume," he said. Mitrofanov and co-authors used the changing nature of the relief of these regions, measured more than two years ago by the Global Surveyor's laser altimeter science team, to explore the implications of the changes.

Mars Odyssey's trio of instruments, the gamma ray spectrometer suite, can identify elements in the top meter (three feet) or so of Mars' surface. Mars Global Surveyor's laser altimeter is precise enough to monitor meter-scale changes in the thickness of the seasonal frost, which can accumulate to depths greater than a meter. The new findings show a correlation in the springtime between Odyssey's detection of dissipating carbon dioxide in latitudes pole ward of 65° north and Global Surveyor's measurement of the thinning of the frost layer in prior years.

"Odyssey's high-energy neutron detector allows us to measure the thickness of carbon-dioxide at lower latitudes, where Global Surveyor's altimeter does not have enough sensitivity," Mitrofanov said. "On the other hand, the neutron detector loses sensitivity to measure carbon-dioxide thickness greater than one meter, where the altimeter obtained reliable data. Working together, we can examine the whole range of dry ice snow accumulations," he said. "The synergy between the measurements from our two 'eyes in the skies of Mars' has enabled these new findings about the nature of near-surface frozen materials, and suggests compelling places to visit in future missions in order to understand habitats on Mars," said Dr. Jim Garvin, NASA's Lead Scientist for Mars Exploration.

Another report, to be published in the Journal of Geophysical Research - Planets, combines measurements from Odyssey and Global Surveyor to provide indications of how densely the winter layer of carbon-dioxide frost or snow is packed at northern latitudes greater than 85°. The Odyssey data are used to estimate the mass of the deposit, which can then be compared with the thickness to obtain a density. The dry ice layer appears to have a fluffy texture, like freshly fallen snow, according to the report by Dr. William Feldman of Los Alamos National Laboratory, NM, and 11 co-authors. The study also found once the dry ice disappears, the remaining surface near the pole is composed almost entirely of water ice.

"Mars is constantly changing," said Dr. Jeffrey Plaut, Mars Odyssey project scientist at JPL. "With Mars Odyssey, we plan to examine these dynamics through additional seasons, to watch how the winter accumulations of carbon dioxide on each pole interact with the atmosphere in the current climate regime," he said.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/jun/HQ_03216_Frosty_Mars.html.

(Added 06/26/03) Starting the week of June 22, 2003, the ESA's Solar and Heliospheric Observatory (SOHO) will experience a blackout in data transmission for about three weeks. This problem is due to a malfunction in the pointing mechanism of the satellite's high-gain antenna which is used to transmit large amounts of data from SOHO to Earth.

In the meantime, the spacecraft will still be operable and as safe as it was before, due to the low-gain antenna - omni-directional, being used to control the craft and monitor instrument and craft health and safety.

The anomaly in the high-gain antenna pointing was recently discovered when engineers detected a discrepancy between the command and measured antenna position. Normally, the antenna can move horizontally and vertically, but the horizontal movement was no longer correct. The problem is probably due to a malfunction in the motor or gear assembly that steers the antenna.

Located at the First Lagrangian, 1.5 million km (1 million miles) from Earth, where the gravity from the sun and Earth cancel out to create a natural orbit-locking mechanism for craft. If the problem is not solved, the high-gain antenna will continue to rotate in and out of Earth's direction, in which case similar blackouts will continue to occur every three months.

Adapted from the press release on http://www.esa.int/export/esaCP/SEMWPBWO4HD_index_0.html.

(Added 06/26/03) Computer models have been the key to nearly everything - from population growth to designing drugs - for decades, and the models continue to be refined, improved, and expanded. Such is the case for models of the sun. Solar physicists Jun Lin (Harvard-Smithsonian Center for Astrophysics) and Terry G. Forbes (University of New Hampshire) have developed a state-of-the-art computer model for the massive solar eruptions called coronal mass ejections (CME's).

CME's threaten satellites, communications networks, and power grids. They are giant bubble-shaped balls of plasma and magnetic field lines that expand and travel outwards at speeds up to 2,400 km per sec (1,500 miles per sec). They can eject up to 91,000 metric kilotons (100 million tons). Thus, the ability to predict CME's is very important scientific, governmental, and commercial endeavor.

The new model matched observations by the Smithsonian Astrophysical Observatory's Ultraviolet Coronagraph Spectrometer (UVCS) on the SOHO satellite, which observed a CME in April of 2002. "By building on four decades of modeling work conducted by many researchers, we have developed a computer code to describe the entire development of a solar eruption from beginning to end. By improving our understanding of the physics behind these blasts, we hope to improve our ability to predict them," said Lin.

The powerful computer model developed by Lin and Forbes simulates the evolution of CME's. Of particular importance, the model calculates the final configuration of the CME's magnetic field, which determines what the effect will be on the Earth - a magnetic field oriented opposite the Earth's leads to more dramatic and disruptive impacts. The Lin and Forbes model is the first to predict that a long current sheet is a key feature of CME's. The current sheet is a region where oppositely directed magnetic fields annihilate one another, in a process known as magnetic reconnection, releasing magnetic energy to accelerate and heat a CME as it erupts from the sun's surface and blasts outward through the solar corona.

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0315.html.

(Added 06/19/03) A collaboration between NASA's Chandra X-ray Observatory and Hubble Space Telescope (HST) is beginning to reveal new clues of the origin and evolution of galaxies. "This is the first time that the cosmic tale of how galaxies build themselves has been traced reliably to such early times in the universe's life," says Mauro Giavalisco, head of the HST portion of the survey, and research astronomer at the Space Telescope Science Institute (STScI) in Baltimore, MD.

HST Field So far, these two space telescopes have surveyed a relatively broad portion of sky that contains tens of thousands of galaxies, some of which are several billion light-years distant (right is the HST optical image). The Space Infrared Telescope Facility (SIRTF), to be launched in August 2003, will soon join this survey, called the Great Observatories Origins Deep Survey (GOODS). Astronomers are using the survey to ascertain the assembly history of galaxies, the evolution of their stellar populations, and the energy from star formation and active nuclei powered by supermassive black holes.

In the Astrophysical Journal publication of preliminary results, HST astronomers report that the sizes of galaxies increase continuously from when the universe was 1 billion years old to the age of 6 billion (the universe is estimated to be 13.7 billion years old). Also found was star birth rate rose by a factor of 3 between the time when the universe was 1 billion years old to 1.5 billion years old, and remained high until the age of 7 billion years, when it quickly dropped to about 10% of its former rate. This is further evidence for major galaxy building tapering when the universe was half its current age.

The galaxy size results are consistent with the "bottom-up" models of growth, where galaxies grow through mergers and accretion of smaller satellite galaxies. It is also consistent with the theory that the sizes of galaxies match a certain fraction of the sizes of their dark matter halos.

When comparing the Hubble and Chandra fields, astronomers also found that active black holes in distant, relatively small galaxies were rarer than expected. This may be due to the effects of early generations of massive stars that exploded as supernovae, evacuating galactic gas and thus reducing the supply of gas needed to feed a supermassive black hole.

These and other results from the GOODS project will be published in a special issue of the Astrophysical Journal Letters, entirely devoted to the team's results. The Chandra results are found in papers led by Koekemoer and Stefano Cristiani of the Trieste Astronomical Observatory. Hubble's findings came from papers led by Giavalisco, Mark Dickinson, and Harry Ferguson of the STScI.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/18/.

(Added 06/19/03) the Chandra Deep Field North image (left) was made by observing an area of the sky 3/5 the size of the full moon for 23 days. It is the most sensitive or "deepest" x-ray exposure ever made. The faintest sources produced only one x-ray photon every 4 days.

More than 500 x-ray sources are present in this high-energy core sample of the early universe. Most of the sources are supermassive black holes located in the centers of galaxies. If the number of supermassive black holes seen in this patch of the sky is typical, the total number detectable over the whole sky at this level of sensitivity would be 300 million.

By combining the Chandra and Hubble Space Telescope (HST) data for this field, astronomers can take a census of the fraction of young galaxies that contain active supermassive black holes back to a time when the universe was only about one billion years old - less than 10% of its present age. The data show that these very distant supermassive black holes are rare, more so than expected.

The data indicate that it takes about 700 million years for a supermassive black hole to accumulate the millions of solar masses of gas needed to produce a powerful x-ray source. The relatively slow growth of the supermassive black holes may be due to a reduced gas supply created when early generations of massive stars exploded as supernovas and blew gas out of the galaxies.

Chandra Deep Field South However, it is possible that a few supermassive black holes could have formed earlier. Seven mysterious sources have been detected in the Southern Deep Field by Chandra (right), but not by the HST. These sources, which are likely supermassive black holes, have also been detected in infrared. The optically invisible sources could be central black holes in unusually dusty galaxies where the optical radiation is absorbed by the dust. Or, the mysterious sources could be candidates for the most distant galaxies ever observed. In the latter case, the red shift due to the expansion of the universe has shifted the optical radiation to infrared wavelengths, and we are seeing them as they were when the universe was only about 500 million years old.

The detection of most of the mystery sources at infrared wavelengths is consistent with either explanation. Further observations at x-ray, optical and infrared wavelengths will be needed to determine the exact nature of these objects.

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_061903.html.

(Added 06/19/03) On April 10, astronomers announced that a gamma-ray burst (GRB) observed on March 29 was linked to a supernova 2.65 billion light-years away. Data supporting this will be published in the July 1 issue of The Astrophysical Journal Letters. Gamma-ray bursts are intense, short-lived bursts of gamma radiation seen from Earth, first discovered in 1967.

The discovery, made by Harvard-Smithsonian Center for Astrophysics (CfA) astronomers Dr. Thomas Matheson and Dr. Kryzstof Stanek, and Dr. Peter Garnavich of Notre Dame, is based upon data from the March 29 GRB analyzed with the 6.5 m MMT telescope at Mount Hopkins in AZ. "There should no longer be doubt in anybody's mind that gamma-ray bursts and supernovae are connected," said Matheson.

Located in the constellation Leo, the 30-sec burst outshone the entire universe in gamma rays and its optical afterglow was still over a trillion times brighter than the sun two hours later. The linking evidence is the burst's afterglow: Its light patters are the same as a supernova (the giant explosion that signals a massive star's death, forming a neutron star or black hole), specifically the absorption lines for silicon and iron atoms.

"For the first time, we were measuring an event no other human beings had seen before," said Stanek. "The MMT was our magic time machine that we used to capture this catastrophic cosmic event." Previous observations, particularly from NASA's Chandra X-ray Observatory controlled at the CfA in Cambridge, MA, have provided convincing indirect evidence of the gamma-ray burst/supernova connection. Chandra detected iron and other heavy elements, which are formed in supernovae, in the vicinity of gamma-ray bursts.

"All gamma-ray bursts may have associated supernovae that are too faint to observe," Matheson said, "but this burst, named GRB 030329, was one of the closest known." "We caught it in the act," said Stanek.

"Our spectra are remarkably similar to the Type Ic 'hypernova' SN1998bw, meaning that the gamma-ray burst is clearly associated with a hypernova explosion - an event ten times more powerful than a typical supernova. We've seen such hypernova explosions in nearby galaxies, although without an accompanying powerful gamma-ray burst, so we'll be watching this distant explosion closely to see if it continues to fit the hypernova profile," said Garnavich.

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0314.html.

(Added 06/15/03) Everyone knows Earth is round. Everyone knows stars are round. But they are not perfect spheres. Due to their spin, large bodies tend to bulge around the middle; this phenomenon is easily visible in photos of Jupiter and Saturn. Now, a team using the VLT Interferometer at the ESO Paranal Observatory have found a star whose equatorial radius is more than 50% larger than its polar radius.

The star, Achernar (Alpha Eridani), is the brightest in the southern constellation Eridanus (The River). Achernar has a mass of 6 times that of the sun. The surface temperature is about 20,000 K and it is located at a distance of 145 light-years. About 20,000 data points were taken over the course of 20 hours, and they show that the ratio between the axes is 1.56 ± 0.05 at the minimum.

At the distance to the star, the corresponding stellar radii are equal to 12.0 ± 0.4 and 7.7 ± 0.2 solar radii, or 8.4 and 5.4 million km, respectively. This presents a problem for stellar astronomers, in particular concerning mass loss from the surface enhanced by the rapid rotation (the centrifugal effect) and also the distribution of internal angular momentum (the rotation velocity at different depths).

The scientists conclude that Achernar must either rotate faster (and hence, closer to the "critical" (break-up) velocity of about 300 km/sec) than what the spectral observations show (about 225 km/sec from the widening of the spectral lines) or it must violate the rigid-body rotation. The observed flattening cannot be reproduced by the "Roche-model" that implies solid-body rotation and mass concentration at the center of the star. The failure of that model is even more evident if the so-called "gravity darkening" effect is taken into account - this is a non-uniform temperature distribution on the surface which is certainly present on Achernar under such a strong geometrical deformation.

Adapted from the press release on http://www.eso.org/outreach/press-rel/pr-2003/pr-14-03.html

(Added 06/14/03) After two days of rain delay, the first of two rovers in NASA's Mars Exploration Rover (MER) mission launched from Cape Canaveral Air Force Station, FL, on June 10, 2003. The rover is on a seven-month mission to the red planet where it will land on January 4, 2004 (UT).

Lift-off occurred aboard a Delta II launch vehicle at 1:58:47 P.M. EDT. The probe separated from the Delta II's third stage about 36 minutes after the launch, and was heard from at 2:48 EDT by the Canberra, Australia's antenna that is part of NASA's Deep Space Network. The rover had originally been scheduled to be launched on June 8, but poor weather conditions held back the launch. The first of the twin rovers in the MER project, this one is named "Spirit."

Throughout its journey, the craft will perform a series of tests and calibrations. It also may adjust its trajectory a total of six times.

Adapted from the press release on http://www.nasa.gov/vision/find/mars_spirit_launch.html

(Added 06/12/03) The European Space Agency's (ESA) XMM-Newton x-ray observatory has allowed a team of European astronomers to make the first direct measurement of a neutron star's magnetic field. The results will help astronomers to understand the extreme physics that occurs in neutron stars and may help unravel puzzles as to the formation of them. Neutron stars are relatively common, but they still contain mysteries.

Neutron stars are very hot when born, but cool rapidly. Thus, only a few of them emit high-energy radiation, such as x-rays. Therefore, they are usually studied in radio wavelengths. However, the neutron star 1E1207.4-5209 does emit in x-rays, and so can be studied by the ESA's XMM-Newton.

In the longest ever XMM-Newton observation of a galactic source (72 hours), Professor Giovanni Bignami of the Centre d'Etude Spatiale des Rayonnements (CESR) and his team have directly measured the strength of its magnetic field. This makes the first ever isolated neutron star where this has been achieved.

Previously, all magnetic field measurements of neutron stars were indirect - based upon theoretical models or the slowing of its rotation rate, as measured by radio astronomy. The direct measurements are based upon cyclotron resonance absorption lines*. In this star, they reveal its magnetic field to be 30 times weaker than predictions based upon the indirect methods.

One way to explain this discrepancy is that there is a drag factor - it is the drag between the star and its magnetic field that causes the slow down of spin rate - that is unaccounted for. One possibility is that there are supernova debris surrounding the neutron star, adding to the friction. The question to answer now - besides if this is the case - is whether this is unique or if it is to be the first of many.

* As x-rays leave a neutron star, they have to pass through the star's magnetic field. This field absorbs certain wavelengths, creating specific absorption lines in the spectrum. These are the cyclotron resonance absorption lines that allow the direct measurement of the magnetic field strength.

Adapted from the press release on http://www.esa.int/export/esaCP/SEM1E0T1VED_index_0.html; this will appear in this week's issue of Nature.

(Added 06/12/03) Presque Isle, Maine, holds the world's largest scale model of the solar system, due to be dedicated on June 14, 2003. Four years of hard, loving work by community volunteers working off of a $0 budget and the inspiration of geology professor Kevin McCartney at the University of Maine at Presque Isle.

The center of the solar system is at the University. The rest extends for 40 miles along U.S. 1, with Pluto - an inch in diameter - mounted on the wall of a visitor information center in Houlton. At scale, 11.26 km per hour (7 mph) would be light speed, taking about 8.3 minutes to travel from the center to where Earth is mounted.

Mercury is 2 inches in diameter and resides in a garden by the highway. Venus is 5 inches, and is in a motel parking lot. Earth is a bit larger than a softball and is located next to the Chrysler-Jeep-Dodge sign at Percy's Auto Sales. Mars is about 3 inches in diameter and is on the top of a pole next to the "Welcome to Presque Isle" sign. Jupiter is 5 feet in diameter, weighs close to a ton, took kindergarten through high school students six months to paint, and is next to a potato field. Seven moons were created, and they are mounted next to their respective planets by poles stuck in the ground.

In order to paint the models, students looked at NASA photographs and mixed acrylic paints to get the correct tones. To build the larger planets, such as Jupiter and Saturn, instructors and students at the Caribou Regional Applied Technology Center were convinced to design and weld. Students from the school's auto body shop added fiberglass. Many other volunteers carted the planets around, from construction area to paint area to the place where they will reside. Still other farmers and businesses donated land for the planets to reside.

The project will be formally completed when Uranus is placed on its base in the town of Bridgewater on June 13, the day before Senator Susan Collins and other dignitaries are expected for the dedication ceremony the following day.

Adapted from the information on http://www.cnn.com-2003-TECH-space-06-07-solar.system.road-index.html

(Added 06/06/03) The Hubble Heritage Team has released June's image of NGC 2736, AKA the Pencil Nebula, a supernova remnant that is part of the larger Vela Nebula. 825 light-years from us, the Pencil Nebula lies in the constellation Vela; this image covers approximately 3.3 arcminutes across (0.78 light-years). The image was originally taken October 21, 2002, for a total exposure time of 3 hours.

The Pencil Nebula was discovered in the 1840's by Sir John Herschel, and its linear appearance gave rise to its popular name. It's shape suggests that the still-expanding shock wave (from right to left in the image) that spawned the Vela Nebula has run into a dense concentration of gas, the interaction causing the glow. This view is of the edge of a rippling sheet of gas.

The impact of the shock wave with the dense interstellar medium causes the gas to heat to millions of Kelvins. As the gas then cools, it emits radiation in the optical wavelengths which is what the Hubble Space Telescope has recorded. In this image, the color of the gas indicates the relative temperature (blue is hotter, red is cooler).

The original supernova left a pulsar in the core of the Vela nebula. Based upon the current rate at which the pulsar's spin is slowing, astronomers estimate that the supernova may have occurred about 11,000 years ago. No historical records of this event exist, but if the age is accurate, the explosion would have been 250 times brighter than Venus and would have been easily visible to southern observers in broad daylight. This would also mean that the explosion pushed material from the star at about 35 million km per hour (22 million mph). The expanding gas is slowing down; the Pencil Nebula is currently moving at about 640,000 kmph (400,000 mph).

Adapted from the information on http://heritage.stsci.edu/2003/16/index.html.

(Added 06/04/03) The first rover in NASA's Mars Exploration Rover (MER) project, involving two identical lander rovers to explore Mars, is set to launch on June 8, 2003. It will arrive at Mars on January 4, 2004. The second rover could launch as soon as June 25, 2003, and arrive at Mars on January 25, 2004. Each rover should operate for at least three months.

Both rovers will lift off from Cape Canaveral Air Force Station, FL, on Delta II launch vehicles. Launch opportunities for the first mission begin at 2:06 P.M. (EDT) June 8 and for the second mission at 12:38 A.M. (EDT) June 25, and repeat twice daily, for up to 21 days, for each mission.

The main goal of these landers is to help understand the role of water in Mars' past -- and possibly its present. "We will be using the rovers to find rocks and soils that could hold clues about wet environments of Mars' past," said Dr. Cathy Weitz, MER program scientist at NASA Headquarters. "We'll analyze the clues to assess whether those environments may have been conducive to life."

Once the landers arrive at Mars, they will enter the atmosphere, inflate an array of air bags, and use the air bags to bounce "safely" until they settle on the surface. The landing sites were chosen previously, and they offer a combination of safe terrain and interesting features.

Each rover has a panoramic camera at human-eye height and a miniature thermal emission spectrometer with infrared vision to help identify rocks to study. The rovers will be able to watch for hazards and move around them. Each six-wheeled rover has an array of solar panels - about the size of a kitchen table - for power during the mission on Mars. To study rocks, the rover will use a microscopic imager for a close-up of the rock's texture. Two spectrometers will be used to determine the composition of the rock. Finally, a hammer-like instrument will be used to expose the interior of a rock by scraping away the surface.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/may/HQ_03189_ROVERS.html

(Added 06/03/03) Europe's first mission to Mars, Mars Express, lifted off from Baikonur Cosmodrome at 1745:26 GMT (1:45:26 P.M. EDT) on June 2. The three core Soyuz stages all fired and jettisoned on time and placed the craft on an escape orbit for Mars. An orbiter, Mars Express, and lander it carries, Beagle 2, are now on a near-seven-month journey to the red planet.

After the 2,500-pound Mars Express separated from its booster 92 minutes into the flight, ground controllers established contact with the craft, confirming that the systems were operating normally and that the solar arrays had deployed correctly. Ground controllers will soon run several tests and checks of the systems and instruments.

Up to three course correction maneuvers might be needed to refine the orbital path of Mars Express on its way to Mars. Especially important will be accurate guidance and instruction just before Beagle 2 separates from the lander on December 19, 2003. The lander has no propulsion systems of its own to correct its heading, so the initial detachment will need to be made especially precise.

Beagle 2 should land in the Isidis Basin in Mars' equatorial region. Its heat shield will protect it from friction in Mars' atmosphere, and parachutes will help slow the descent. Air bags will protect the lander from impact stresses. The landing should take place on December 25, 2003, at approximately 2:00 A.M., European time.

Beagle 2's air bags will then deflate and its four solar arrays will open, allowing a robotic arm to begin the scientific goals of the mission. This 27 kg (72 lb) craft will search for water, carbon molecules, potential organic molecules, and it will study the surface geology, contents of the atmosphere, and study the meteorology of the landing site area.

Mars Express will enter its final orbit on December 26, 2003, and it will spend at least two years studying Mars. Searching for water is the primary goal, but it will also study other atmospheric and surface features, as well as create a full-color map at a resolution of about 10 meters (33 ft). After the mission has ended, it will serve as a communications relay for future and / or current Mars exploration and missions.

The concept behind Mars "Express" is a fast and cheap way of achieving the most science. At a cost of only $350 million, Mars Express and Beagle 2, if successful, will pave the way for future fast and cheap exploratory craft.

Ways in which the cost was reduced was by using a lot of "off-the-shelf" technology or technology copied from ESA's Rosetta comet probe. Thus the technology development costs were drastically reduced as well as the time needed to plan and construct the orbiter and lander. The ESA has already approved the Venus Express mission, which will use a similar design to explore Venus. This mission is slated for late 2005.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/mars/marsexpress/030602launch.html.

(Added 05/29/03) A group of scientists from the National Radio Astronomy Observatory (NRAO) and Caltech who are studying the closest identified Gamma-Ray Burst (GRB) to-date have been able to reduce the number of viable models to explain these and to refine ones that are still viable.

GRB's were first discovered in 1967 by a satellite that was monitoring the atmosphere for nuclear tests. For three decades, no one knew where or how these energetic bursts originated. In 1997, the National Science Foundation's (NSF) Very Long Array (VLA) detected the first radio after-glow from a GRB and the first distance measurements were made.

Most GRB's originate 8-10 billion light-years away, but the one under study, occurring on March 29, 2003, lies only 2.6 billion light-years away. This burst, GRB 030329, is the closest GRB that has been observed. The after-glow was observed several times between April 1 and May 19.

The data have yet to be completely analyzed, but they have already ruled out one popular model for how GRB's form. The so-called "cannonball" model says that the radio-wave energy comes from "cannonballs" of material that are shot from the explosion at near-light speeds. This model predicted that the radio-emitting object would move across the sky by a specific and measurable amount. Observations show that the object has, in fact, remained stationary.

The most popular model that is still viable is the "fireball" model, which says that radio waves are emitted by a rapidly-expanding shock wave. As the shock wave expands, the emissions should become fainter but remain stationary, which the observations support.

As the data are analyzed further, measurements of the size and expansion rate can begin to put limits on the energy involved, and the physics of these energetic phenomenon can be better-understood.

Adapted from the press release on http://www.nrao.edu/pr/2003/grb030329/.

(Added 05/23/03) In the first of its kind, an image of Earth and Moon taken from Mars has been released. The NASA spacecraft Mars Global Surveyor (MGS) is currently orbiting Mars, and took this picture as seen from the evening sky of Mars at 9 A.M. EDT on May 8, 2003. Taking advantage of a relative Earth-Jupiter alignment as seen from Mars, MGS also took saw Jupiter and three moons (below; from left to right, the moons are Callisto, Ganymede, and Europa; Io was behind Jupiter at this time).

"From our Mars orbital-camera perspective, we've spent the last six-and-a-half years staring at Mars right in front of us," said Dr. Michael Malin, president and chief scientist of Malin Space Science Systems (MSSS) of San Diego, who operates the camera aboard MGS. "Taking this picture allowed us to look up from that work of exploring Mars and take in a more panoramic view. This image gives us a new perspective on that neighborhood, one in which we can see our own planet as one among many."

Jupiter, Callisto, Ganymede, and Europa from MGS Earth is seen as a crescent due to the position of the sun in relation to Mars and Earth. The image has been processed to make both Earth and the moon to be visible together, for Earth is much brighter in contrast to the moon. The Jupiter image has also been processed to allow the same contrast.

The bright area in the upper right part of Earth is cloud cover over East and Central North America. Below that, the darker area includes Central America and the Gulf of Mexico. The bight area below that is more cloud cover over northern South America. The slightly lighter color in the lower part of the moon is the ray system associated with the crater Tycho.

MGS, one of the most successful missions to Mars ever taken, has been orbiting since September 1997. The mission has studied the entire martian surface and provided much information, including - but not limited to - the planet's atmosphere and interior, as well as providing high-resolution imagery.

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/may/HQ_news_03179.html.

(Added 05/23/03) For years, it was known that there was an intergalactic cloud, but it was of unknown distance and significance. Recent images obtained with the National Science Foundation's Robert C. Byrd Green Bank Telescope (GBT) have now revealed this so-called "Complex H" object to be crashing through the outer parts of our galaxy in an inclined, retrograde orbit.

Previous studies did not reveal this because Complex H is currently passing almost exactly behind the outer disk of the Milky Way; gas and dust between us and the object blocks almost all visible light. The new study used radio waves - longer wavelengths of light that can pass through the intervening material - in extremely sensitive measurements. They show a dense core moving in a 45° inclined orbit with the plane of our galaxy. A diffuse region surrounds the core which appears to look like a tail trailing behind the central mass that is being slowed from the interaction with our galaxy.

These results are not too surprising: Larger galaxies such as ours grow by "consuming" smaller objects such as galaxies, star clusters, and clouds of gas and dust. There are several galaxies that are currently being incorporated into ours; the two most famous, which also orbit in a retrograde fashion, are the two Magellanic Clouds. The irregular rotation is probably due to chaotic motion early in our galaxy's history - objects were not moving in all the same direction.

The GBT observations show Complex H being 108,000 light-years from the galactic center, the object is about 33,000 light-years across, and it contains approximately 6,000,000 solar masses of hydrogen.

The GBT is the world's largest fully steerable radio telescope; it was commissioned in August, 2000, and is frequently outfitted with sensitive receivers and components that allow it to make observations at higher frequencies.

Adapted from the press release on http://www.nrao.edu/pr/2003/complexh/, which will appear in the July 1 issue of the Astrophysical Journal, Letters.

(Added 05/17/03) Images taken of Neptune over the past six years by the Hubble Space Telescope (HST) show an increase in the brightness of Neptune's southern hemisphere, which is considered to be a major sign of seasonal change.

"Neptune's cloud bands have been getting wider and brighter," says Lawrence A. Sromovsky, a senior scientist at the University of Wisconsin-Madison's Space Science and Engineering Center. "This change seems to be a response to seasonal variations in sunlight, like the seasonal changes we see on Earth."

The three sets of HST observations (taken in 1996, 1998, and 2002) in which a full rotation of the planet were obtained show progressively brighter clouds in the planet's southern hemisphere. The relatively constant brightness near equatorial regions bolsters the evidence that this is a real seasonal change, which would be more pronounced at higher latitudes. The observations are consistent with observations and predictions made by G.W. Lockwood at Lowell Observatory, which show that Neptune has been gradually brightening over the last two decades.

Unlike Earth, where seasons typically last for three months, Neptune's seasons can last for over 40 years due to the planet's 165-Earth-year year. If these patterns truly are a season change, the planet should continue to brighten over the next 20 years.

What is remarkable, according to Sromovsky, is that Neptune shows any seasonal change. Seasons are caused by different amounts of direct solar energy falling on a given area. Thus, the 23.5° tilt in Earth's axis gives the seasons on our planet. Neptune has a 29° axial tilt, but the sun is 900 times dimmer on Neptune than it is from Earth.

Adapted from the information on http://hubblesite.org/newscenter/archive/2003/17/, which appears in the May 2003, issue of Icarus, a leading planetary science journal.

(Added 05/09/03) Muses-C, the Japanese probe that hopes to land on an asteroid and bring back samples for study, has begun is multi-year mission. Liftoff aboard an M-5 rocket occurred from Kagoshima Space Center at 0429 GMT (12:29 A.M. EDT) with the probe placed into a transfer orbit within minutes of launch.

See the internal Muses-C link above for information on its mission.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/news/n0305/09musesc/.

NGC 1275 - Active Galaxy (Added 05/09/03) The most recent release from the Hubble Space Telescope is an image of NGC 7293, AKA the Helix Nebula, a planetary nebula. 650 light-years from us, the Helix Nebula lies in the constellation Aquarius; this image covers approximately 27 arcminutes across (5.1 light-years). The image is a compilation of images taken on November 3, 2001, and November 19, 2002, for a total exposure time of 5 hours.

This image has been released in celebration of Astronomy Day. It is a compilation of images from Hubble and the Mosaic Camera on the National Science Foundation's 0.9 m telescope at Kitt Peak National Observatory, part of the National Optical Astronomy Observatory near Tuscon, AZ. Oxygen is blue and hydrogen and nitrogen are red.

One of the closest nebulas to us, it appears nearly half the diameter of a full moon. The image shows a trillion-mile-long tunnel of glowing gasses, pointed directly at Earth. Thousands of comet-like filaments point towards the central star - a small white dwarf.

Adapted from the information on http://hubblesite.org/newscenter/archive/2003/11/.

M31 - Andromeda Galaxy (Added 05/08/03) The most recent release from the Hubble Space Telescope is an image of a section of M31, AKA NGC 224, AKA the Andromeda Galaxy, a spiral galaxy that is the closest large neighbor of our Milky Way. 2.5 million light-years from us, the Andromeda Galaxy lies in the constellation Andromeda; this image covers approximately 3.1 arcminutes across (2300 light-years). The image is a compilation of images taken in December, 2002, and January, 2003, for a total exposure time of 3.5 hours.

The image represents the deepest visible-light images ever taken in space, and has been used to measure the age of the spherical halo of stars surrounding the Andromeda Galaxy. The the surprise of the investigators, they discovered that approximately 33% of the stars formed only 6-8 billion years ago - just over half as old as the 11-13 billion-year-old stars that form our halo.

The best bet as to this major difference is that M31 went through a major merger with another large galaxy or a series of mergers with smaller galaxies billions of years ago -- which cannot be told yet. The young stars are richer in heavier elements than the Milky Way's halo.

These suggest three possible scenarios of the evolution:

Collisions destroyed the young disk of M31 and dispersed many of its stars into the halo.
A single collision destroyed a relatively massive invading galaxy and dispersed its stars and some of Andromeda's disk stars into the halo.
Many stars formed during the collision itself.

Previously, telescopes could only see the bright giant stars in the halo population, but the population of "normal" stars like the sun was beyond detection because the stars are so far away and faint. The new Advanced Camera for Surveys that was recently installed on the Hubble is the first camera to combine the ultra-sharp vision and sensitivity to find M31's faint halo population.

An estimated 300,000 of these never-before-seen halo stars can be resolved. Also visible beyond the halo stars reveal thousands of background galaxies (down to 31^st magnitude). A large portion of the background galaxies also have peculiar shapes due to collisions.

Adapted from the information on http://hubblesite.org/newscenter/archive/2003/15/.

(Added 05/08/03) In April of 2001, India launched its first rocket under the Geostationary Satellite Launch Vehicle (GSLV) program - India's attempts to become self-sufficient for the construction and launch of its own spacecraft. The GSLV-2 satellite has now launched successfully, as well, providing another step towards India's goal of indigenous access to space for a wide range of payloads.

GSLV-2 lifted off at 1128 GMT (7:28 A.M. EDT) from the Satish Dhawan Space Center in Sriharikoa, India, along the Bay of Bengal. Approximately 17 minutes after launch, the rocket deployed its GSAT-2 satellite payload into an elliptical orbit with an apogee of 36,000 km (22370 miles) and a perigee of 180 km (112 miles) at an inclination of 19.2°.

The first signals that were received at the ground stations at Biak showed normal performance, according to the Indian Space Research Organization. The next plan for the 1.5 metric-ton (4000 pound) satellite is to be boosted into a circular geostationary orbit along the equator at 48° E at an altitude of 32,888 km (22,300 miles) above the Indian Ocean.

The satellite contains a radiation instrument, electrical charge detector, spectrometer for solar flares, a beacon to study the atmosphere using radio signals, and six transponders for conducting communications tests and experiments.

Future plans in the program include a GSLV-3 launch in 2005 and a lunar exploration mission within the next decade.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/news/n0305/08gslvd2/.

(Added 05/03/03) Recent data collected with the Hubble Space Telescope (HST) suggest that the first stars had formed as soon as 200 million years after the Big Bang - much earlier than previously thought. The finding hinges on observations of iron in very distant and old quasars.

Iron was not formed in the birth of the universe from nucleosynthesis, but is formed in the cores of massive stars during nuclear fusion. The iron is released in the violent eruptive supernovas of these stars. The entire process after birth takes between 500-800 million years for the massive stars. The first generation of stars were huge - possibly over 100 times that of our sun - and their deaths seeded space with heavy elements.

Therefore, the detection of iron in these ancient supernovas at a red shift of about 20 is highly suggestive that stars had already formed at this early time in the universe's history. This is much earlier than previously thought, but is in agreement with results from the Wilkinson Microwave Anisotropy Probe.

In October 2002, a team lead by Wolfram Freudling used HST's NICMOS (Near Infrared Camera and Multi-Object Spectrograph) to observe three of the most distant quasars known (red shifts of 5.78-6.28), corresponding to about 900 million years after the Big Bang. The large amounts of iron found in these represent the first time elements that were created in the first generation of stars have been found.

These observations show that stellar populations could have preceded the formation of super-massive black holes that power quasars and are in the centers of most large galaxies. Other observations show that quasars were born slightly before 900 million years after the Big Bang, so the first stars also preceded them. This is the first major scientific result to come from NICMOS since it was revived during the Hubble Servicing Mission 3B in 2002.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/news/n0305/02firststars/.

(Added 05/03/03) Mercury, the closest planet to the sun, completes one orbit every 88 days. However, it transits - passes in front of the sun relative to Earth - only about 12 times per century. One of those events will take place this Wednesday, May 7, 2003.

NASA's Solar and Heliospheric Observatory (SOHO) will be in an ideal position to observe the event. It will also offer live, safe views of the transit to people with an internet connection: http://soho.nascom.nasa.gov/hotshots/2003_05_07/. Observers in Asia, Africa, and Europe will have the best view of the transit, which will already be in progress as the sun rises over America at around 6:00 A.M., EDT. The transit will last approximately 5 hours, though viewers in America will only see the last 20-30 minutes of it. The event will have finished by the time the sun rises west of a line from the Great Lakes to the Carolinas.

The transit cannot be seen with the unaided eye, since Mercury's apparent size is only 1/160 of the sun's diameter. Direct telescope viewing is NOT recommended, since special precautions must be taken to avoid permanent eye damage.

SOHO is situated at a position 1.6 million km (1 million miles) between Earth and the sun, in order to make continuous observations of solar activity. One of its instruments, the Large Angle and Spectrometric Coronagraph, will be able to see Mercury a few days before it transits the sun. Other instruments will track its progress across the sun's disk during the transit. The images will be available for download immediately from the website.

Mercury and Venus, being the only planets inside Earth's orbit, are the only ones that can transit the sun from our perspective. Venus transits are rarer than Mercury's, coming in one pair eight years apart every 105 to 121 years. "The last Venus transit was in 1882, so no one live has seen one," said eclipse expert Fred Espenak of NASA's Goddard Space Flight Center, Greenbelt, MD. "Happily, there will be a Venus transit June 8, 2004, so this year's Mercury transit can be taken as an appetizer for the main course."

The transits are historically very important. "Venus transits were the Apollo project of the 18th and 19th centuries. There were major international efforts, with scientific expeditions to remote corners of the world, in order to measure the apparent position of Venus on the solar disk. Using trigonometry and a careful analysis of observations, astronomers could determine the actual distances to Venus and the sun. Captain James Cook, the legendary British navigator and explorer, recorded the transit of Venus from Tahiti in 1769. The observation was a major motivation for his expedition to the South Pacific and the circumnavigation of the globe."

Adapted from the press release on http://www.nasa.gov/home/hqnews/2003/may/HQ_news_03152.html.

NGC 1275 - Active Galaxy (Added 05/03/03) The Hubble Heritage Team has released May's image of NGC 1275, AKA Perseus A, an active galaxy. 235 million light-years from us, NGC 1275lies in the constellation Perseus; this image covers approximately 0.8 arcminutes across (57,000 light-years). The image was originally taken November 16, 1995, and November 6 and 15, 2001, for a total exposure time of 4 hours.

The picture shows a large, dusty spiral galaxy that is rotating on edge - like a pinwheel - as it slides through the larger, brighter galaxy NGC 1275. The image montage show traces of spiral structure accompanied by vivid dust lanes and bright blue regions that mark areas of active star formation.

Detailed observations of NGC 1275 indicate that the dusty material belongs to a spiral system seen nearly edge-on in the foreground. The second galaxy, lying behind the first, is a giant elliptical with very faint spiral structure in its nucleus. The two galaxies are believed to be colliding at speeds greater than 9.6 million kph (6 million miles per hour). The two galaxies are in a large cluster known as the Perseus Cluster.

NGC 1275 is a powerful x-ray and radio source. The galactic collision causes the gas and dust already existing in the central bright galaxy to swirl into the center of the object. The x-ray and radio emission indicates the probably existence of a black hole in the bright galaxy's center.

As the dark, dusty material falls inward, NGC 1275 shows intricate filamentary structures at a much larger scale that is outside the range of this image. This is a typical feature of bright cluster galaxies. Additional observations show strong interactions between at least two galaxies, and possibly a few smaller ones, and includes the formation of new stars and large star clusters. Although the clusters are similar in shape to the Milky Way's they are much younger than the Milky Way's ancient (11.3+ billion years) ones.

Adapted from the information on http://heritage.stsci.edu/2003/14/index.html.

(Added 04/27/03) For the first time, scientists have peered through the smoggy orange haze of Saturn's largest moon, Titan, and discovered that the surface is not entirely covered by liquid and solid organic materials that rain through the atmosphere. Extensive areas of icy bedrock lie exposed on Titan's surface. "Titan's surface reflectivity looks a lot like that of Jupiter's moon, Ganymede. This is somewhat surprising because Titan is believed to have a lot of organic gook on its surface," said Caitlin A. Griffith of the University of Arizona Lunar and Planetary Laboratory.

Titan's atmosphere is ten times as massive as Earth's, and it is primarily nitrogen that is laced with poisonous substances such as methane and ethane. The atmosphere was impenetrable to cameras aboard the Pioneer and Voyager spacecrafts that traveled to Saturn in the late 1970's and early 1980's.

This dense hydrocarbon fog forms the high, massive atmosphere; in the upper stratosphere, methane is destroyed by sunlight, with the byproducts reacting with other molecules in Titan's atmosphere, forming organic droplets of particles that fall onto the moon's surface forming lakes and oceans. Scientists have measured and modeled the rate of methane photolysis, and from that deduced how much material annually settles out of the atmosphere.

Since 1991, Griffith and others have developed and used a technique that allows observers to spectroscopically view the surface at several narrow infrared "windows," or regions between the very thick methane bands. The project involved use of the United Kingdom Infrared Telescope and NASA's Infrared Telescope Facility, both on Mauna Kea, Hawaii, to observe at eight near-infrared windows.

These results appeared in the April 25, 2003, issue of Science.

The findings are relevant to the NASA / ESA Cassini mission that will arrive at Saturn in July 2004.

Adapted from the press release on http://uanews.opi.arizona.edu/cgi-bin/WebObjects/UANews.woa/5/wa/SRStoryDetails?ArticleID=7248&wosid=gQzN8i4LtpKRoN6lKtaXxg.

M17 - Swan Nebula - Emission Nebula (Added 04/25/03) The newest release from the Hubble Space Telescope is of a section of M17, AKA the Swan Nebula, an emission nebula. 5,500 light-years from us, the Swan Nebula lies in the constellation Sagittarius; this image covers approximately 1.9 arcminutes across (3.1 light-years). The image was originally taken on May 29/30, 1999 for a total exposure time of 3.4 hours.

The Swan Nebula resembles the fury of a raging sea, but is an image of glowing hydrogen with small amounts of oxygen and sulfur. In the image, red represents sulfur, green is hydrogen, and blue is oxygen.

This image, a small region of M17, has been released to commemorate the thirteenth anniversary of Hubble's launch on April 24, 1990.

The wave-like patterns of gas have been sculpted and illuminated by ultraviolet radiation from a myriad of young, massive star, which lie outside the picture to the upper left. The glow of these patterns accentuates the three-dimensional structure of the gases. The ultraviolet radiation is carving and heating the surfaces of cold hydrogen gas clouds. The warmed surfaces glow orange and red in this image. The intense heat and pressure cause some material to stream away from those surfaces, creating the glowing veil of even hotter greenish gas that masks background structures. The pressure on the tips of the waves may trigger new star formation within them.

Adapted from the information on http://hubblesite.org/newscenter/archive/2003/13/.

(Added 04/15/03; updated 04/20/03) NASA has chosen two scientifically interesting landing sites for twin robotic rovers to explore on the Martian surface early next year in the Mars Exploration Rover (MER) mission. The first is a giant crater that appears to have once held a lake, and the second is a broad outcropping of a mineral that usually forms in the presence of liquid water. Each MER rover will examine its landing site for geological evidence of past liquid water and environmental conditions hospitable to life.

The map to the left is a global topological map of Mars. The higher elevations are shown in white to red, while the lower ones are purple to blue. Marked on it are the locations of where the past Martian exploration vehicles have landed, along with the planned sites for MER.

The first rover, scheduled for launch on May 30, 2003, will be targeted for Gusev Crater, 15° S. The second, scheduled for launch on June 25, 2003, will be targeted for Meridiani Planum, an area with iron oxide that lies 2° S and on the opposite side of the planet from Gusev.

Which will be targeted for which can still change as late as about one month after the launch of the first rover, and is contingent upon more simulations. The first will land on Mars on January 4, 2004, and the second on January 25, 2004. Once down, each mission will last 90 Martian (92 Earth) days. The rovers are solar-powered, and during those three months, dust accumulation will likely diminish the power supply.

Adapted from the press release on http://www.nasa.gov/home/HP_news_03137.html.

TWA 5B Brown Dwarf (Added 04/14/03) Using the Chandra X-ray Observatory orbiting above the light-bluring effects of Earth's atmosphere, a team of astronomers headed by Tokyo's Chuo University's Yohko Tsuboi has detected and resolved x-rays from a low mass brown dwarf in a multiple star system. The system is as young as 12 million years old, and lies in the constellation Hydra, 180 light-years away. This discovery is an important piece in the complex puzzle of how very massive planets and brown dwarfs evolve around other stars.

Brown dwarfs are commonly known as "failed stars." They failed to accrete enough material to reach the critical mass of approximately 80 Jupiters that is needed in order to start the nuclear fusion process - the criterion for a "live" star.

Chandra's observations of the brown dwarf, known as TWA 5B, clearly resolve it from the binary star system that it circles, as shown in the image to the right. The brown dwarf orbits at a distance about 2.75 times Pluto's from our sun. This is the first time that a brown dwarf this close to its parent star(s) has been resolved in x-rays.

The fact that it could be resolved at all is something that only Chandra can perform with its angular resolution of about 1/2 arcsec. TWA 5B is "200 times dimmer than the primary and located just two arcseconds away," said Gordon Garmire of Penn State University who lead the ACIS** team. It glows as brightly as our sun in x-rays, even though it is only 2% of its mass.

TWA 5B weighs in at between 15-40 M_J*, making it one of the least massive brown dwarfs known. Because of this, the conclusions drawn from this research could have implications for massive extra-solar planets, such as those that have already been discovered.

The research on TWA 5B also provides a link between an active x-ray state in young brown dwarfs (1 million years old) and a later, quieter period when they reach ages of 500 million to 1 billion years.

* Due to Jupiter's bulk, objects that are not a full-blown star yet are still very massive are generally weighed in terms of "Jupiters." M_J is shorthand for writing this. Extra-solar planets are considered to be bodies that are smaller than about 12 M_J, though there is no exact cut-off point that has been defined between brown dwarfs and massive extra-solar planets.

** The Advanced CCD Imaging Spectrometer (ACIS) was the instrument that was used on April 15, 2001 for three hours in order to record the x-ray image of TWA 5B.

Adapted from the press release on http://chandra.harvard.edu/press/03_releases/press_041403.html.

CRL 2688 - Egg Nebula - Protoplanetary Nebula (Added 04/03/03) The Hubble Heritage Team has released April's image of CRL 2688, AKA the Egg Nebula, a planetary nebula. 3,000 light-years from us, the Egg Nebula lies in the constellation Cygnus; this image covers approximately 86 arcseconds across (1.2 light-years). The image was originally taken on September 27, 2002 and October 15/16, 2002 for a total exposure time of 1.5 hours.

The Egg Nebula offers astronomers a look at the usually invisible dust shells that surround aging stars. The layers extend approximately 0.1 light-years from the star (6300 times Earth's orbital distance from the sun).

The layers have an onion-like structure that forms concentric rings around the star. A thicker dust belt that runs almost vertically through the center of the image blocks light from the central star. Twin beams of light radiate from the hidden star and illuminate the normally dark dust.

The Hubble Space Telescope's Advanced Camera for Surveys has filters that allow light that vibrates only at certain angles to enter. This is a composite image of three different polarizations, one colored red, another green, and the final blue. The artificial colors in the image are used to determine how the light reflects off the smoke-size particles and then journeys to Earth.

Studying the polarized light from the Egg Nebula allows scientists to learn a lot about the physical properties of the material responsible for the scattering, as well as the location of the central, hidden, star. The dust is largely carbon, manufactured by fusion in the core of the star and then ejected into space as the star sheds material. Such dust is essential for building dusty disks around future generations of young stars, and possibly the formation of planets around those stars.

Adapted from the information on http://heritage.stsci.edu/2003/09/index.html.

(Added 03/26/03) Before January 2002, the last light from a stellar explosion that was seen reflecting off dust in the Milky Way was in 1936. Now, with the high resolution offered by the Hubble Space Telescope (HST), the outburst of the star V838 Monocerotis (V838 Mon) is offering stellar astronomers a three-dimensional view of the structure of dust shells surrounding an aging star.

V838 Mon lies approximately 20,000 light-years from Earth. Fourteen months ago, this dull, obscure star flared into view when it became 600,000 times more luminous than our sun, temporarily making it the brightest star in our galaxy. Even though the star has long-since faded, its "light echo" from reflections off of dust in its vicinity are providing us with an "astronomical cat-scan" of the space around the star.

The lead observer, Howard Bond of the Space Telescope Science Institute in Baltimore, MD, and his team used HST images to study the shells of dust that were presumably ejected in previous outbursts. Because the light bounces off the dust particles, it can arrive here several months after the initial burst.

V838 Mon Maximum Size The burst was similar to a nova, but V838 Mon did not expel its outer layers. Instead, it grew enormously in size (see image at left), consequently causing its surface temperatures to drop to temperatures not much hotter than a light bulb *. "We are having a hard time understanding this outburst, which has shown a behavior that is not predicted by present theories of nova outbursts," explains Bond. "It may represent a rare combination of stellar properties that we have not seen before.

The star may represent a transitory stage in stellar evolution that is rarely seen. The star has some similarities to highly unstable aging stars called eruptive variables, which suddenly and unpredictably increase in brightness.

The light echo feature has expanded to an area of the sky that is twice the angular size of Jupiter. Astronomers expect it to continue expanding as reflected light from farther out in the dust envelope finally arrives at Earth. Bond predicts that the echo will be observable for the rest of this decade.

* The reason temperature drops when the star expands lies in that it still produces the same amount of energy as when it was smaller. Now, with more volume to fill, the energy is more spread out and so the same parcel of energy falls over a larger area of the star's surface and so cannot heat it as much.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/10/.

(Added 03/24/03) The densest objects in the universe, black holes, have fallen into two main classes for mass - solar-sized that dot the galaxy and form from the supernovas of giant stars and supermassive black holes that power quasars and are thought to lie at the center of most galaxies. Until recently, there has been no evidence for black holes of a few hundred or thousand times the mass of our sun.

The first evidence for these medium black holes was found in 1989 with the Einstein X-ray Observatory. They were designated as ultra-luminous X-ray sources (ULX's), for they are exceedingly bright yet compact. Over the last three years, several observations provided compelling evidence that ULX's were black holes, yet scientists could not rule out the possibility that these bright objects were less exotic sources with all of their energy beamed in our direction, making them appear intrinsically brighter than they really are.

New x-ray observations when combined with recent optical and radio observations strongly support the intermediate black hole interpretation for two two specific ULX's NGC 1313 X-1 and NGX 1313 X-2, both lying in the spiral galaxy NGC 1313 about 10 million light-years from Earth. The observations focused on the temperature of the gas orbiting the black holes - the accretion disk.

The inner ring of the accretion disk, closest to the black hole, is the hottest part of the disk, glowing primarily in X-ray light. Perhaps counter-intuitive, however, is the black hole theory predicting that the inner ring of an accretion disk is hotter in small, stellar-mass black holes compared to supermassive black holes. This is because spacetime curves more gently near a large black hole than near a small one. Thus, the material falling into a supermassive black hole remains cooler over this greater amount of material.

The researchers found the temperatures of NGC 1313 X-1 and X-2 to be in line with black holes containing at least 100 solar masses, and likely 200 to 500 solar masses. While evidence supporting the existence of intermediate-mass black holes continues to flow in, scientists still do not know how such black holes would form. "Three basic scenarios have been suggested," says Cole Miller, "direct collisions and mergers of stars within globular clusters; the collapse of extremely massive stars that may have existed in the early Universe; or the merger of smaller black holes. Each scenario has strengths and limitations."

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0309.html.

(Added 03/19/03) New observations of a Gamma Ray Burst - a class of events that are characterized by an intense burst of gamma radiation from events that are not yet understood - offers proof that the observed event was the death of a gigantic star and the birth of a gigantic heavy object - likely a black hole - in its place.

The observations, featured in the March 20, 2003 issue of Nature, is the most detailed to date and confirm the so-called "collapsar" model where the bursts are produced by the demise of the most massive stars in the universe.

This is a follow-up story based on a 03/19/03 NASA press release to the story featured here "Two Gamma Ray Bursts Show New Features" which was based upon a Harvard-Smithsonian Center for Astrophysics press release on 03/10/03 (story here on 03/13/03). See that story for more information.

The image presented here is a composite of four images from a computer simulation of the formation of a gamma ray burst. In order: (1) the inner 10% core of a Wolf-Rayet star - an extremely massive class of bluish stars with a mass 10-15 times our sun's - this shows the iron, oxygen, and carbon shells; (2) due to a lack of fuel, the star can no longer support itself against the pull of its own gravity and the core of a black hole forms; (3) a jet of material escapes through the polar regions, possibly powered by renewed fusion and spin of the black hole; (4) a close-up of the jet of material formed in the stellar core pierces through the star's surface, traveling at close to light speed.

Adapted from the press release on http://www.nasa.gov/HP_news_03107.html; caption information from http://www.gsfc.nasa.gov/topstory/2003/0319hete.html.

Artist's Conception of an Evaporating Hot Jupiter

Image courtesy of NRAO/AUI and M. Bietenholz

(Added 03/18/03) Neutron stars, a dense, compact remnant of a star, sometimes releases intense jets of radiation, which, due to the rapid rotation rates of these stars, pulse at us several times a second.

This variation on the neutron star, a pulsar, is at the heart of the Crab Nebula - a supernova remnant that was formed on June 4, 1045. The Crab Pulsar is one of the most-studied pulsars known; it pulses at a rate of approximately 33 times per second.

A team of astronomers has now discovered variations in the pulses on the scale of under two nanoseconds. This means that the variations must originate from an area that is smaller than two light-nanoseconds - about 0.67 m (2 ft) in diameter.

This new finding promises to shed light on some of the hidden properties of pulsars. The researchers say that the very short subpulses can only be generated by a process in which the density waves of charged particles in the star's magnetic poles interact with themselves and their own electrical field, becoming denser until they reach a point where they "collapse explosively" into superstrong bursts of radio waves.

Adapted from the press release on http://www.aoc.nrao.edu/epo/pr/2003/pulsaremission/.

(Added 03/13/03) For the first time, astronomers using the Hubble Space Telescope (HST) have observed the atmosphere of an extra-solar planet evaporating around star HD 209458. Most of the planet may eventually evaporate, leaving behind only a dense core.

The planet orbits approximately 7,000,000 km (4,000,000 miles) from its Sun-like star, leading to a year of only 3.5 days. The planet is 1/3 times Jupiter's diameter and 2/3 its mass. For this reason it falls into the class of a "Hot Jupiter" - a massive planet in a very close orbit.

HST's observations show a giant cloud of hydrogen around and behind the planet, much like the tail of a comet. The atmosphere extends over 200,000 km (124,000 miles). The outer atmosphere is extended so far and heated so much that it has enough energy to escape the planet's gravity, and thus evaporate; the evaporation rate is at least 10,000 tons per second, but possibly much more.

The planet lies too close to its star to be seen directly, as do all extra-solar planets. It was found when it was seen eclipsing part of HD 209458 - an event also called a transit. The transit also changes the spectroscopic signature of the star, for the star's light also passes through the planet's atmosphere. The HST's Imaging Spectrograph was used to measure this, and a drop in hydrogen emission was noted; a huge puffed up atmosphere is the best explanation.

The parent star is similar to the sun and lies 150 light-years from Earth. It is visible with binoculars as a seventh magnitude star in the constellation Pegasus. In 1999, this star suddenly entered the astronomical "Hall of Fame" when HD 209458b was seen passing in front of the star and partly eclipsing it. This was the first confirmed transiting extrasolar planet ever discovered. In 2001, Hubble detected the element sodium in the lower part of HD 209458b's atmosphere, the first signature of an atmosphere on any extrasolar planet.

The image presented here is an artist's conception, NOT an actual photograph.

Adapted from the press release on http://hubblesite.org/newscenter/archive/2003/08/.

(Added 03/13/03) It has been known for many years that both Earth and Venus have liquid cores. Now, researchers at NASA's Jet Propulsion Laboratory have determined that Mars, too, has a liquid core.

This finding comes after three years of precise radio tracking of the NASA Mars Global Surveyor (MGS) spacecraft. The same forces that cause the tides on Earth - the gravitational pull of the sun and Moon - also cause tides on Mars. Mars, with no liquid water oceans, shows this tidal pull from the sun with a bulge of less than a centimeter in its crust. (Earth's crust also has a bulge, but this is not nearly as profound as the oceanic tides.)

This tiny tidal bulge affects Mars' gravity field, which affects the orbital path of the MGS. By the precision tracking of MGS's orbit, the scientists can determine how flexible the planet is based upon how the bulge travels over Mars. This is then compared to models of the planet's interior, and the only models that fit the data show that Mars has a partially liquid core.

These gravity results, combined with information about Mars' precessional rate of 170,000 years*, also indicate that Mars' core is approximately 1/2 the size of the planet, as it is for Earth and Venus, and that the core consists of a significant amount of light material, such as sulfur.

* The precession is best explained with a top: A top rarely spins with its axis perfectly straight up and down. Instead, its rotational axis is tilted and traces out a circle. This is known as precession. Earth's precesses at a rate of approximately 25,000 years for one revolution. The rate is indicative of the amount of material concentrated in the center: A faster precession rate indicates a larger dense core compared to a slower precession rate.

Adapted from the press release on http://www.nasa.gov/HP_news_03094.html.

(Added 03/13/03) Gamma ray bursts (GRBs), the most energetic explosions in the universe, are one of the least-understood events. The most widely accepted theories are that GRBs result from the merging of two black holes or two neutron stars, or from the supernova from a massive star - a hypernova. The explanation for why they are so bright is that the energy is focused into two narrow jets.

Recently, two observed bursts by astronomers at the Harvard-Smithsonian Center for Astrophysics provide new data that can help test previous models and help theorists come up with a better picture of what GRBs really are.

The first burst indicated that the light was highly polarized. When light is polarized, its constituent waves oscillate in the same direction; unpolarized light waves oscillate in all directions equally. David Bersier and his colleagues observed GRB 020405 with the MMT 6.5-meter telescope at Mount Hopkins, Arizona, on April 6, 2002. This observation took place approximately one day after the GRB was recorded, and the astrophysicists recorded a 10% polarization in the light - more than any other observed GRB. Interestingly, observations made a few hours after and a few hours before show a polarization in the light of 2%.

The second burst, GRB 021004, discovered by the orbiting High Energy Transient Explorer (HETE) satellite on October 4, 2002, had observations of it begin less than 10 minutes after the blast. Observations showed that it featured variations on time scales of 15-30 minutes, meaning that the object(s) that produced the blast must be less than 30 light-minutes across.

The astronomers believe that the variations were caused by density variations in the interstellar matter, and that the matter was close to the source, which means the GRB was probably caused by a hypernova. The light curve of this GRB is the best-sampled to date with over 100 data points. Besides these variations, the GRB showed a significant increase in intensity while the light was fading, and it also showed an intrinsic color change, which has only been observed in one other burst and which no model can account for.

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0308.html.

NGC 1705 - Irregular Dwarf Galaxy (Added 03/06/03) The Hubble Heritage Team has released March's image of NGC 1705, an irregular dwarf galaxy. 16.6 million light-years from us, NGC 1705 lies in the constellation Pictor; this image covers approximately 33 arcseconds across (2,600 light-years). The image was originally taken in March 1999 and November 2000 for a total exposure time of 18 hours.

At such a far distance, the individual stars in this galaxy can only be resolved by the Hubble Space Telescope. These stars represent an ideal situation to study star formation history, for there are young, hot, blue stars near the center, while older, cooler, red stars are more evenly spread. A recent burst of star formation between 26-31 million years ago triggered the formation of the blue stars as well as the central giant star cluster.

This galaxy is called an irregular dwarf because it is small and lacks any regular structure. Many galactic astronomers believe that such dwarfs were some of the first galaxies to form in the early universe, and they are the building blocks from which larger galaxies such as the Milky Way were later formed.

Adapted from the information on http://heritage.stsci.edu/2003/07/index.html.

(Added 03/04/03) The People's Republic of China has proposed detailed plans to explore the moon - Earth's closest celestial neighbor - according to the state-run news sources that quoted leading Chinese scientists in the field. Unmanned orbiters, landers, and rovers could be sent to study the lunar landscape over the next decade; a sample return mission has also been suggested, which would make China the third nation to have brought lunar samples to Earth (the U.S. and Russia did this over 30 years ago).

The program, "Chang's Program" named after a traditional Chinese legend about a fairy flying to the moon, still has yet to obtain government approval, approval which would be needed soon if the first launch date in 2005 is to be kept. The 2005 proposed launch would consisted of a lunar orbiter to map the surface in detailed tragedians images.

A robotic explorer would follow to study the surface and composition, as well as the surrounding environment in order to learn more about the moon and to plan for future missions. Then, focus would be on remote-controlled rovers to bring back lunar material.

To minimize material and development costs, already existing technology, such as the Long March 3A rocket, would be put to use rather than completely new and costly designs.

This announcement comes a few months before the expected launch of the Shenzhou 5 craft which will be the nation's first manned flight in October.

Adapted from an article on Spaceflight Now's website at http://spaceflightnow.com/news/n0303/04china/.

(Added 03/02/03) The Cassini spacecraft, en route to Saturn where it should arrive in July, 2004, has been used to discover a massive donut-shaped cloud - a torus - around Jupiter.

The cloud is the result of severe bombardment by ion radiation from Jupiter on Europa, one of the four largest moons of Jupiter. The radiation hits Europa's surface, releasing and pulling apart water ice molecules and disperses them in a path in the moon's orbit. The cloud's mass is approximately 60,000 tons.

The large mass of the cloud shows that Europa has considerable influence on the configuration of Jupiter's magnetic field.

Adapted from the press release on http://www.nasa.gov/HP_news_03086.html.

(Added 02/27/03) Launched on March 2, 1972, Pioneer 10 was to be the first human spacecraft to traverse the asteroid belt and visit any of the outer planets. On December 3, 1973, it became the first craft to pass Jupiter, and in 1983 the first to pass beyond Pluto. It is the fastest-traveling human-made spacecraft at a speed of 32,400 mph.

Truly a pioneer in space technology, its original 21-month mission has finally come to an end after almost 371 months. The last, very weak signal from Pioneer 10 was received on January 22, 2003.

NASA engineers have determined that its radioisotope power source has decayed, and that it does not have enough power to send additional transmissions to Earth, and the last contact attempt was February 7, 2003.

Pioneer 10's twin, Pioneer 11, suffered the same fate on September 10, 1995. Pioneer 10 was able to continue to make valuable scientific contributions through March 31, 1997, and since then, its signal had been tracked by the Deep Space Network (DSN) as part of an advanced-concept study of communication technology in support of NASA's future Interstellar Probe mission. When it was last contacted, Pioneer 10 was 7.6 billion miles from Earth, where it took over 11 hrs, 20 minutes for a radio signal to reach us.

The craft will continue to travel through space in the direction of the red star Aldebaran, the eye of the bull, Taurus, 68 light-years away. It will take the craft over 2,000,000 years to reach it.

Adapted from the press release on http://www.nasa.gov/HP_news_03082.html.

(Added 02/27/03) The search for information about the very young universe has been pursued ever since the discovery of Cosmic Microwave Background Radiation (CMB) left over from when matter combined to form the first atoms, a process called recombination. Now, NASA has released the most-detailed images of this early stage of the universe.

The Wilkinson Microwave Anisotropy Probe (WMAP) took data from the entire sky with unprecedented accuracy over a period of one year.

From the data, astrophysicists have been able to determine that the first stars were created only 200,000,000 years after the Big Bang, which is much sooner than many models had predicted. The data also determine that the universe is 13.7 ± 1% billion years old.

It also confirms inflation theory as well as the composition of the universe being approximately 4% "ordinary" matter, 23% dark matter, and 73% dark energy.

The maps of the CMB released represent the universe when it was only 380,000 years old. They are extremely small (less than 1/1,000,000 of a degree) fluctuations in 2.73 K background temperature. The top map shows the data from the COBE craft, the first to take an all-sky map of the CMB; its resolution was quite low. The bottom map shows the WMAP data; red indicates warmer temperatures, and blue indicates cooler temperatures.

Based upon the size of the largest fluctuations, cosmologists are able to determine the overall geometry of the universe; these latest observations uphold the conclusion that the universe is a flat, Euclidian, geometry where parallel lines will never meet and the interior angles of a triangle add to 180°.

WMAP will continue to take measurements for three more years, and astronomers hope that its data will shed even more information on inflation and the nature of dark energy.

Adapted from the press release on http://www.nasa.gov/HP_news_03064.html.

(Added 02/26/03) As reported here on January 15, 2003, amateur astronomer Dr. Leon Stuart of Oklahoma photographed what he believed to be a huge fireball of vaporized rock rising from the moon's surface in the morning of November 15, 1953. He believed that he witnessed an asteroid impact on the moon, and if he was right, Dr. Stuart would be the first and only human in history to view and document an asteroid impact on the moon.

However, for nearly 50 years, no image had been made to document a resulting crater. However, Dr. Bonnie J. Buratti of NASA's Jet Propulsion Laboratory and Lane Johnson of Pomona College, CA, believe they have found the impact crater. From the original photograph, they were able to determine that the resulting crater would have been too small to be seen by even the best Earth -based telescopes.

Selecting a 35 km- (21.75 mile-) wide region where they believed the crater would lie, they looked at images taken of that area by spacecraft. They were looking for a crater approximately 1-2 km (0.6-1.3 miles) across that they believe was caused by an object 20 m (65.6 ft) across; what would tell them if they had found it would be lack of erosion, emphasized by a "fresh" bluish tinge of lunar surface.

From Clementine images taken in 1994, they located a 1.5 km (0.93 mile) diameter crater with a bright blue layer of material surrounding it in a location consistent with Dr. Stuart's photograph.

Dr. Stuart died in 1969, but his son, Jerry Stuart, said "[astronomy] was my father's passion, and I know he would be quite pleased."

Adapted from the press release on http://www.nasa.gov/HP_news_03077.html.

M27 - Dumbell Nebula (Added 02/26/03) The Hubble Heritage Team has released February's image of M27, more popularly known as the Dumbell Nebula and also designated NGC 6853. 1240 light-years from us, the Dumbell Nebula lies in the constellation Valpecula; this image covers approximately 2.1 arcminutes across (0.8 light-years). The image was originally taken on November 19, 2001 in a 2.4 hour exposure.

A planetary nebula, M27 actually represents the first such nebula discovered; it was first spied by Charles Messier in 1764.

The many knots that can be seen in the image are many times the size of Pluto's orbit and they contain as much as three times Earth's mass. These were formed by the interaction between hot and cool parts of the nebula, with the hot area moving outwards as the nebula continues to expand.

Adapted from the information on http://heritage.stsci.edu/2003/06/index.html.

(Added 02/10/03) Since gamma-ray bursts were discovered a few years ago, one of the main questions has been what causes them, and if they originate within our galaxy or are of extragalactic origin.

The main technique used to observe these massive torrents of energy is for satellites to detect them and automatically relay the information of position to ground-based telescopes to search for a visible-light afterglow. Studies in the past have been able to link gamma-ray bursts to extragalactic objects.

The leading theory is that this energy splurge is a result of massive neutron stars merging to form a black hole or a neutron star merging with a black hole.

Now, for the first time, data of an afterglow has been taken starting within a record 108 seconds after the 2.5-second burst was recorded by the High Energy Transient Explorer (HETE) - 2 craft. 34 seconds after the burst, an e-mail alert was sent out and the RAPTOR (Rapid Telescopes for Optical Response) telescope acquired a short-exposure image of the area 64 seconds after the e-mail. Then, the Katzman Automatic Imaging Telescope in Santa Cruz, CA, stared to observe the afterglow for the next 2.5 hours when dawn halted observations.

The afterglow was extremely short-term, and astrophysicists Alex Filippenko of the University of California, Berkeley and his team hope that it will help explain the "dark" gamma-ray bursts which don't seem to have any visible-light counterparts. He suggests that it might be that any visible-light source has faded in the past before observations were able to be made.

Adapted from: Cowen, Ron. "Gamma-ray burst leaves ephemeral afterglow." Science News 1 February 2003: 77. Original reference was a January 9 meeting of the American Astronomical Society in Seattle.

(Added 02/01/03) This morning, at approximately 9:00 A.M., the Space Shuttle Columbia exploded at an altitude of approximately 61.887 km (203,000 ft) above north-central Texas during re-entry en route to the Kennedy Space Flight Center in Florida. This is the first shuttle accident since the Challenger explosion during lift-off on January 28, 1986.

As of yet, there is no definitive evidence as to the exact nature of the accident, although any terrorist activity is ruled out due to the altitude of the craft, and, as Time has stated, "It would be easier to plant a bomb on Air Force One than on a space shuttle."

Once the facts get put together, there will be an in-depth review of the accident here.

(Added 01/23/03) The Rosetta mission has now been postponed for at least a year. Because of this, the original target of Rosetta, comet Wirtanen, will not be obtainable. The Rosetta team is looking for alternative targets for the orbiter and lander mission that would be within the timeframe for a launch within the next 2.5 years.

The criteria that Wirtanen and any comets that the team may choose to target are as follows:

Maximize scientific return.
Minimize technical risks to the spacecraft.
Careful estimates of extra funding needed (current cost projections of grounding the mission range between € 50-100 million).

The new targets will be presented at the meeting of the Science Programme Committee between February 25-26, 2003. The final decision for targets is expected in May 2003, at the latest.

Despite the setbacks, Project Scientist Gerhard Schwehm is still optimistic: "During the decade it has taken us to develop and build Rosetta, we have faced many challenges and overcome them all. This new challenge will be met with the same energy, enthusiasm and, ultimately, success."

The craft is now being safely and cleanly stowed away, its batteries and lander harpoons removed, and its fuel tanks drained.

Adapted from the press release on http://sci.esa.int/content/news/index.cfm?aid=13&cid=36&oid=31326.

(Added 01/23/03) Until recently, the number of known moons around Neptune had totaled 8. Not so anymore, for a team of astronomers led by Matthew Holman and JJ Kavelaars has discovered three previously unknown moons, bringing the total to 11. Not only are these the first new moons found around Neptune since 1989 when Voyager 2 encountered Neptune, but these are the first new moons found via a ground-based telescope since 1949 (Nereid, found by Gerard Kuiper).

The moons are extremely small, at estimates ranging from 20-40 km (12-24 miles) in diameter. They are 100,000,000 times fainter than can be seen with the unaided eye; due to this, a new method of detecting the moons was implemented.

This involved using the 4.0 m (13 ft) Bianco telescope in Chile and the 3.6 m (11.8 ft) Canada-France-Hawaii telescope in Hawaii. The team, also consisting of Tommy Grav, Wesley Fraser, and Dan Milisavljevic, took multiple images of the sky surrounding Neptune. They then digitally tracked the planet as it moved and added images together to boost the brightness of any faint objects. Because the planet was tracked, stars appeared as streaks while moons appeared as points.

The team is now refining their measurements and observations, and are conducting additional observations using the 5 m (16 ft) Hale telescope at Mt. Palomar, one of the four 8.2 m (26.9 ft) telescopes of the European Southern Observatory's Very Large Telescope in Chile, and the 2.6 m (8.5 ft) Nordic Optical Telescope in Spain.

The goal is to help refine the bulk parameters of the moons, such as mass, diameter, orbital distance, and period. The moons have been designated as S/2002 N1, S/2002 N2, and S/2002 N3 (the above image shows S/2002 N1); the International Astronomical Union has the only official ability to give the moons official names.

Adapted from the press release on http://cfa-www.harvard.edu/press/pr0303.html.

(Added 01/19/03) The Rosetta probe, which was supposed to be launched on January 12, 2003, was postponed again on January 14, 2003: "Having considered the conclusions of the Review Board set up to advise on the launch of Rosetta, Arianespace and the European Space Agency have decided on a postponement."

The Review Board has called for Arianespace and all of its partners to make sure that all of the systems will work within the framework of the Rosetta program. Arianespace and the ESA are going to meet to determine when Rosetta will launch.

Adapted from the press release on http://www.esa.int/export/esaCP/Pr_4_2003_p_EN.html.

(Added 01/18/03) The first image of Saturn from the Cassini craft was taken on October 21, 2002, and First Saturn Image from Cassini appears to the right. The craft was still 20 months away from its July 2004 rendezvous date, which corresponded to approximately 285 million km (177 million miles) - almost twice the distance between the sun and Earth.

The image of Saturn shows summer in its southern hemisphere with the sun 27° below the equator, casting an oblong shape on the underside of the rings, as well as the rings casting a shadow over the upper part of the planet.

Besides the planet, the largest moon of Saturn, Titan, can also be seen in the upper left corner of the image. It is the only Saturnian moon that can be resolved at Cassini's present position. It is the moon that the Huygens probe will penetrate in order to learn more about its atmosphere and surface features; many scientists believe that there are many organic processes currently going on on the moon which closely resemble early Earth prior to life.

The image is a composite of three separate images taken in different colors, and has been color and brightness enhanced in order to bring out Titan relative to Saturn.

Adapted from the press release on http://saturn.jpl.nasa.gov/cgibin/gs2.cgi?path=../gallery/saturn/images/image30.jpg&type=image.

(Added 01/16/03) Over half a century ago, the German-American astronomer Walter Baade divided stars into three categories: Population I, Population II, and Population III. These categories referred to the ages of the stars, mostly based upon their metalicity. Population I stars are relatively young, high in metals, and include our sun. Population II stars are much older, are metal-poor, and are usually found in globular clusters and the galaxy's halo. Population III stars are the first stars that formed after the Big Bang, and contain almost no metal whatsoever.

Until now, most astronomers have believed that observation of Population III stars was well-beyond our capabilities, especially because most Population III stars were between 100-1000 times the size of the sun, so would have died billions of years ago. However, a team using the the European Southern Observatory's 8.2 m (26.9 ft) Very Large Telescope in Chile has found that the star HE 0107-5240 contains the least metal of any star ever detected. The ratio of its iron to hydrogen is less than 1/200,000 that of the sun, at only 1 iron atom per 6,800,000,000 hydrogen atoms.

The star lies in the constellation Phoenix, and it is approximately 36,000 light-years away. Although this is not a member of the very first generation of stars, it shows that astronomers may be close to viewing a member of these ancient ones.

Adapted from: Dorminey, Bruce. "A Star without Heavy Elements." Astronomy February 2003: 22, 24.

(Added 01/15/03) An amateur astronomer photographed a bright flash from the moon on November 14, 1953. The flash was believed to have been created from an impact by an asteroid. By using the brightness of the flash and its estimated duration of about 1 sec, Bonnie J. Buratti of NASA's Jet Propulsion Laboratory and Lane L. Johnson of Pomona college were able to estimate the energy, size, and impact. They estimate that the asteroid was approximately 20 m (66 ft) in diameter and that it exploded with the energy of approximately 500,000 tones of TNT, 0.3% of that being converted into energy.

Lunar maps generated by the U.S. Department of Defence satellite Clementine showed a bright, bluish halo approximately 1.5 km (0.93 miles) across, which the two scientists believe to be freshly (relative to the surrounding material) ejected rock and debris. They estimate that the actual crater that was formed, which is too small to be seen with Earth -based telescopes, is 300 m (1000 ft) across and 60 m (200 ft) deep.

Adapted from: Perkins, Sid. "Fresh Crater Found on Lunar Images." Science News 21&28 December 2002: 400. Original reference is from a meeting of the American Geophysical Union that took place in San Francisco during December 6-10.

(Added 01/14/03) Proxima Centauri, the closest star to Earth other than the sun, lies 4.2 light-years away. It is only 15% as large as the sun, but a team of astronomers lead by Damien Ségransan of the Observatory of Geneva in Sauverny, Switzerland, has been able to image its disk - the first star that has been resolved into something other than a point to a high degree of accuracy other than the sun. The star has a diameter of 202,000 km (125,500 miles), which agrees very well with theoretical predictions.

This was accomplished by using the process of inferometry, which combines the light from two or more telescopes to make an image with the resolution of a mirror as large as the distance between the telescopes. The telescopes used were two of the four 8 m (26 ft) telescopes known collectively as the Very Large Telescope in Paranal, Chile.

Adapted from: Cowen, Ron. "Sizing up small stars." Science News 14 December 2002: 381. Original reference is an upcoming Astronomy & Astrophysics.