Other Inner Planets

Overview

The inner solar system, composed of Mercury, Venus, and Mars (besides Earth), has generally presented an easier target for study than the far-off outer planets. Within the last ten years, Mars, especially, has been the most intriguing target for study. So far this century has only seen missions on Mars, both by NASA and the ESA. These include 2001 Mars Odyssey, Mars Express, and Mars Exploration Rovers. Additionally, NASA's Mars Reconnaissance Orbiter has been launched and it should reach Mars in 2006.

Two additional missions that have been launched but not yet reached their targets are NASA's MESSENGER mission to Mercury which should reach the planet in 2011, and ESA's Venus Express mission to Venus that should reach the planet in 2006.

2001 Mars Odyssey

Overview

The 2001 Mars Odyssey was originally called the Mars Surveyor 2001 Project, and was to consist of both a lander and an orbiter. However, due to cut-backs and reorganization, the lander was abandoned and the orbiter set as the only part of the project.

The orbiter is designed to orbit Mars for over five years and to collect data for three of those. The probe is designed to take measurements on Mars' mineral content and atmosphere / environment. One of the main objectives for this project is to attempt to determine if Mars ever had a suitable environment for life to develop. Other objectives are to learn about the climate and geology of Mars, as well as to determine any potential radiation hazards to potential astronaut visitors.

2001 Mars Odyssey was launched on April 7, 2001. After seven months, it reached Mars on October 23, 2001. Over the next three months, it used the Martian atmosphere to aerobrake, and to finally assume a standard orbit on January 30, 2002, of approximately 400 km (250 mile) altitude. It orbits the planet now every two hours.

Besides its primary science objectives, the 2001 Mars Odyssey will also be used as a relay station for rovers that will be sent to Mars later this year (2003), and possibly other probes as well. Even though its 917-day mission ended in July of 2004, NASA extended the mission an additional Martian year through September 2006. Afterwards, if the craft is still working, NASA plans on continuing to use the probe as a relay station for communications with other probes in orbit and on the surface.

Experiments

Neutron Spectrometer (NS):

• This is designed to detect hydrogen on the surface of Mars to a depth of about 1 m. This data will be used to characterize the abundance and distribution of water on Mars. The NS detects neutrons in three energy ranges: thermal, epithermal, and fast.
• The detector is a rectangular block which is divided internally into 4 prisms, one which faces downward towards the planet, or nadir, one faces upward, away from the planet (zenith), one faces into the spacecraft (aft), and one faces out in the direction of the spacecraft velocity (forward). Each prism is a boron-loaded plastic scintillator, optically isolated from the other prisms. Each prism is viewed by a separate photomultiplier tube.
• When an energetic particle strikes the scintillator, a flash of light results which is detected by the photomultiplier tube. The small ends of the box are covered by a thick sheet of cadmium which is an effective shield against neutrons. The downward looking prism also has a cadmium shield so only neutrons above a certain energy can enter.
• Thermal neutrons are low-energy, slow-moving, cosmic-ray generated neutrons which have lost much of their energy in collisions with hydrogen atoms. They are scooped up by the forward prism but outrun by the aft prism. The difference in counting rates between these prisms gives a measure of the thermal neutron flux. The difference in rates between the aft prism and zenith prism gives a fractional measure of epithermal neutrons. The aft prism also measures spacecraft-generated neutrons. Epithermal neutrons are also measured by the shielded nadir prism. The ratio of thermal to epithermal neutrons gives an indication of the amount of hydrogen present in the ground.

High Energy Neutron Detector (HEND):

• This is designed to measure the flux of neutrons at different energies. This data will be used to determine neutron albedo parameters for use in interpretation of the gamma-ray data and to construct a global map of regions with subsurface water or ice. The ratio of slow to fast neutrons gives an indication of the abundance of hydrogen at the surface (because collisions with hydrogen atoms slows neutrons down) and this can be used to estimate the abundance of water.
• HEND is composed of three proportional counter detectors based on Helium-3 LND 2517 counters and polyethylene moderators with cadmium shields: A small detector with a thin moderator for detecting neutrons of energy 0.4 to 10 eV, a medium detector with a thicker moderator (10 eV to 1 keV), and a large detector with a thick moderator (1 keV to 1 MeV). There is an internal scintillation sensor which uses a Stilben crystal and photomultiplier tube (PMT) to detect high energy (300 keV to 10 MeV) neutrons and gamma ray photons from 60 keV to 1 MeV, and an external scintillation sensor using a CsI crystal and PMT for detection of protons with energies above 300 keV and hard X-rays above 30 keV for anti-coincidence rejection.

Thermal Emission Imaging System (THEMIS):

• This instrument consists of a thermal infrared imaging spectrometer and a high-resolution camera which will be used to map the mineralogy and morphology of the surface of Mars. Specifically, THEMIS will be used to characterize localized deposits associated with hydrothermal or sub-aqueous environments, to identify potential sample return sites, to study small-scale geologic processes, and to search for temperature anomalies associated with active subsurface thermal systems, if any exist.
• The THEMIS instrument is 54.5x37.0x28.6 cm in size and is mounted on the spacecraft science deck. It uses an all-reflective, three-mirror f/1.7 anastigmatic telescope with an effective aperture of 12 cm and an effective focal length of 20 cm to focus light onto the infrared and visible detectors via a dichroic beam splitter. The infrared imager detector is a 320 x 240 micro-bolometer array with a field of view of 4.6° crosstrack by 3.5° downtrack. The array temperature will be stabilized by a thermal electric cooler. The filters are mounted directly over the focal plane. The instrument will detect emitted infrared radiance in nine filtered bands between 6.6-15.0 µm. These filter bands are centered at (with full-width half-power bandwidth) in micrometers: 6.62 (1.01), 7.88 (1.09), 8.56 (1.18), 9.30 (1.18), 10.11 (1.10), 11.03 (1.19), 11.78 (1.07), 12.58 (0.81), 14.96 (0.86). The spectrum will include contributions from the atmosphere as well as the surface. The thermal infrared imaging spectrometer will map the entire planet at a resolution of 100 m per pixel.
• The visible imager consists of a 1024 x 1024 silicon array with a 2.9° square field of view. The visible camera will have a resolution of 18 meters per pixel in 5 wavelength color bands centered at 0.423, 0.553, 0.652, 0.751, and 0.870 µm with a bandwidth (full-width half-power) of 0.05 µm. The five stripe filters are mounted directly on the detector. The entire detector array will be read out every 1.3 seconds. Up to 15,000 panchromatic visible images will be returned. The infrared and visible images will be co-aligned.

Gamma Ray Spectrometer (GRS):

• This is used to monitor the gamma rays emitted from the surface of Mars at different energies and from the energy spectrum determine the elements present at the martian surface. These measurements will be used to determine the elemental abundances of the martian surface material including composition of the permanent polar caps, to map the distribution of water and to determine its near-surface stratigraphy, and to determine the thickness of the seasonal polar caps and their variation with time. The instrument will also be used to study the nature of cosmic gamma-ray bursts.
• The GRS is an emission spectrometer consisting of a 1.2 kg high-purity germanium diode as a solid-state detector. The diode is reverse biased to ~3000 volts and has leakage currents <1 nA. Current produced by gamma rays in the diode are amplified by a low temperature pre-amplifier. A radiative cooler covered by a hatch is used to cool the sensor below 90 K. The sensor is surrounded by a thermal shield so it can be heated to 100 C before the orbital measurements to anneal any radiation damage occurring during the cruise phase.
• The GRS is mounted at the end of a six-meter boom to minimize interference from gamma-rays emitted by the spacecraft. The instrument is bowl shaped, 46 cm in diameter at its widest point, the radiator cover at the top of the sensor, and 17 cm high. The detector is nadir-pointed and has a field of view of 144°. The spatial resolution of the GRS is about 300 km, but lower resolution will be necessary for elements with lower count rates. Long integration times will be used to build up spectra which can be interpreted in terms of element abundances.
• The instrument will also be equipped with two neutron detector systems to detect hydrogen. One neutron detector will measure thermal, epithermal, and fast neutrons, the other will primarily measure fast neutrons.

Mars Radiation Environment Experiment (MARIE):

• This is an energetic particle spectrometer designed to measure the near space radiation environment as related to the radiation hazard to human explorers. Specifically, MARIE will determine the energy deposition spectrum from 0.1 keV/µm to 1500 keV/µm, separate the contribution of proton, neutrons, and HZE particles, measure the accumulated absorbed dose and dose rate which would occur in tissue, and determine the radiation quality factor.
• The spectrometer consists of two 24x24 position sensitive detectors (each roughly 2.5x2.5 cm in size) and two 2.5x2.5 cm silicon detectors. These are backed by two 1.78x1.78 cm proportional counters, one total energy proportional counter (TEPC) and one charged proportional counter (CPC). There are two 0.9 µCurie alpha sources and two 40 torr propane vessels. Data is saved on 60 Mb of flash memory and transferred at <8 Mbits per day over an RS-422 low speed data line. The entire unit is 10.2 cm x 17.8x29.2 cm. The field of view is 56° and energy is measured in 512 channels covering the 0.1 to 1500 keV/µm range.
• During the cruise to Mars, in August, the MARIE instrument failed to respond during a routine data transfer and was put into hibernation. Attempts to revive the instrument were successful in March 2002 and MARIE began taking scientific data from orbit on March 13.

Craft Data

Mars Express

Overview

This consists of an orbiter, Mars Express Orbiter, and a lander, Beagle 2. The purpose of the orbiter is to take global high-resolution photography (10 m (33 foot) resolution), mineralogical mapping (100 m (330 foot) resolution) and mapping of the atmospheric composition, study the subsurface structure, global atmospheric circulation, interaction between the atmosphere and the subsurface, and the atmosphere and interplanetary composition. The Beagle 2 lander is supposed to characterize the landing site geology, mineralogy, and geochemistry, the physical properties of the atmosphere and surface layers, collect data on the meteorology and climatology, and to search for possible signatures of life.

The craft was launched on June 2, 2003. It reached Mars on December 26, 2003, but the lander was released on December 21, 2003. The orbiter entered into a highly elliptical orbit, which, after a few days, was altered into a polar orbit that will eventually settle into a 250x11,583 km (155x7200 mile) orbit at 86° of 6.7 hours. This will begin the main mission, and it will last approximately 440 days. Then, the orbit will be modified so that the farthest point will be at 10,243 km (6365 miles) above the surface. The total orbiter mission is planned to last one Martian year - approximately 687 days.

The Mars Express radar system (MARSIS) was deployed between May 2 and June 19, 2005. It was commissioned over the next few weeks, and it began its first science observations in August 2005.

The Beagle 2 entered the atmosphere on December 26, 2003, and released parachutes when it was approximately 1 km (0.62 miles) above the surface. The Beagle 2 lander was declared lost on February 6, 2004, after it had not contacted any orbiting craft nor receiver on Earth.

What was supposed to happen was large gas bags were to inflate around the lander to protect it when it hit the surface. After landing, the bags would deflate and the top of the lander will open to expose four solar array disks. Within the body of the lander, an antenna would have been deployed and the lander arm released. The lander arm would have dug up samples to be deposited in the various instruments for study; the "mole" was to be deployed, crawling across the surface at a rate of about 10 cm (4 inches) per minute and capable of burrowing under rocks to collect soil samples for a gas analysis system.

The Beagle 2 cost roughly 40 million British pounds ($57 to $65 million U.S.) The overall Mars Express budget excluding the lander is 150 million Euros (~$150 million U.S.).

Experiments

High-Resolution Stereoscopic Camera (HRSC):

• This is designed to provide color stereo imaging at multiple phase angles at high resolution and to provide global coverage of Mars. The camera is a push-broom scanning device with 9 CCD's.
• Scientific objectives are to characterize surface morphology, topography, and geological evolution, to identify geologic units, to help refine the geodetic control network, and to analyze atmospheric phenomena including climatology, the role of water, and surface/atmosphere interactions.
• HRSC is derived from the Russian Mars-96 mission.

Infrared Mineralogical Mapping Spectrometer, or Observatoire pour la Mineralogie, l'Eau, les Glaces et l'Activit (OMEGA):

• This is a visible and near-infrared mapping spectrometer designed to provide global data on the mineralogical and molecular composition of the martian surface at medium resolution. The instrument will spectrally analyzed re-diffused solar light and surface thermal emission.
• The scientific objectives are to characterize the composition of surface material and monitor atmospheric dust.
• The OMEGA instrument is derived from the Russian Mars-96 mission.

Atmospheric Fourier Spectrometer, or Planetary Fourier Spectrometer (PFS):

• This is a Fourier infrared spectrometer designed for atmospheric studies. It has two channels, one with a 10 km footprint and one with 20 km.
• The scientific objectives are to return three-dimensional temperature-field measurements of the atmosphere up to 50 km altitude, constituent variations (water and carbon dioxide), and the optical properties of atmospheric aerosols, which will allow the study of global atmospheric circulation, and data on the thermal inertia of the martian surface.
• The PFS instrument is derived from the Russian Mars-96 mission.

Ultraviolet and Infrared Atmospheric Spectrometer, or Spectroscopic Investigation of the Characteristics of the Atmosphere of Mars (SPICAM-UV):

• This is designed to study the atmosphere with nadir- and limb-viewing modes. It will measure the ozone content of the atmosphere, the coupling of ozone and molecular hydrogen, and vertical profiles of carbon dioxide, ozone, and dust (using stellar occultation techniques).
• This data will be used to constrain meteorological and dynamic models of Mars' atmosphere.
• The SPICAM-UV instrument is derived from the Russian Mars-96 mission.

Subsurface Sounding Radar/Altimeter, or Mars Advanced Radar for Subsurface and Ionospheric Sounding (MARSIS):

• This is a multi-frequency nadir-looking instrument which will employ two 20 m antennas, which form a 40 m dipole oriented perpendicular to the flight and nadir directions, to characterize the subsurface structure of Mars to a depth of a few kilometers, provide altimetry and roughness data, and make ionospheric measurements.
• The primary scientific objectives are to map the distribution of liquid water and ice, for studies of Mars' geologic, climatic, and possibly organic evolution.

Energetic Neutral Ions Analyzer, or Analyzer of Space Plasmas and EneRgetic Atoms (ASPERA):

• This consists of a neutral particle imager and ion spectrometer mounted to a scanning platform.
• Its primary scientific objective is to measure the plasma-induced atmospheric escape and the interaction of the solar wind with the martian ionosphere.

Mars Radio Science Experiment (MaRS):

• This will utilize the Mars Express orbiter radio subsystem to characterize dielectric properties of the surface, the martian gravity field, and the neutral and ionized atmosphere (by sounding at occultations).

Lander Communications Relay (MARESS) will be used to communicate with the Beagle 2 lander on the martian surface.

Craft Data

Mars Exploration Rover

Overview

This program is another that plans on landing on Mars. It is designed to take panoramic pictures, search for evidence of past or present water, and perform other experiments on rocks. Scientists from Earth will be able to command the vehicles to specific areas of interest.

It consists of two rovers that are based upon that used in the Mars Pathfinder mission. The first was launched on June 10, 2003, and it landed on January 3, 2004 (GMT). The second rover was launched on July 7, 2003 at 23:18:15 EDT, and it landed on January 25, 2004 at 5:05 GMT.

The rovers are designed to travel approximately 100 m (330 feet) each martian day (24 hours and 37 minutes). Each rover's primary mission lasted for approximately 90 Martian (92 Earth) days. However, they have been successfully operating for nearly a full Martian year, and they have had their missions extended until at least November, 2006, assuming they continue to operate. For more up-to-date information, see the Current Events, and for information on what the craft have discovered, see the Mars page.

Experiments

Panoramic Camera (Pancam):

• This is a pair of high-resolution CCD imagers mounted on the Pancam Mast Assembly. The imagers are side-by-side on a "camera bar" to allow stereo imaging. They are separated by 30 cm horizontally and have a 1° toe-in, giving stereo coverage from roughly 5-100 m. Each camera's optics consists of a protective sapphire window and 3-element symmetrical lenses with an effective focal length of 38 mm and a focal ratio of f/20, giving a field of view of 16.8°x16.8°, or 0.28 mrad/pixel. Optimal focus is from 1.5 m to infinity.
• Each camera has an eight position filter wheel giving multispectral imaging capability in the 400-1100 nm range. The left camera has one clear filter and a set of filters at: 750 nm (±20 nm range), 670 (20), 600 (20), 530 (20), 480 (25), 430 (short-pass filter), and a 440 nm solar filter. The right camera filters are 430 (short-pass), 750 (20), 800 (20), 860 (25), 900 (25), 930 (30), 980 (long-pass), and an 880 nm solar filter.
• The mast can rotate 360° to give full panoramic views and the camera bar can swing up and down 180°, with pointing control better than 2° in azimuth and 1° in elevation. The mast holds the camera about 1.3 m above the surface. Images are 12-bit, captured on a 1024x2048 pixel Mitel CCD array, one 1024x1024 pixel region constituting the active imaging area and the other 1024x1024 pixels acting as a frame transfer buffer. Mosaics as large as 4000x24000 pixels can be generated. Exposure times up to 30 sec are possible. Signal to noise ratio is greater than 200. A target is carried on the rover for calibration of the cameras during the mission. There is also a vertical post to cast a shadow on parts of the target during calibration.

Microscopic Imager (MI):

• This is designed to take highly magnified close-ups of martian rocks and soils. The instrument consists of a microscope and a CCD camera mounted on the rover arm, or instrument deployment device, which can position the imager against its target. The field of view is 1024x1024 pixels and there is a single broad-band filter with a spectral bandpass of 400-680 nm. The optics use a fixed focus design at f/15 that gives ±3 mm depth-of-field. The focal length is 20 mm and the working distance is 63 mm from the front of the lens barrel to the object plane. Resolution is 30 µm/pixel and the field of view is 31x31 mm. The CCD array is 1024x1024 pixels.
• Ambient sunlight will be used to illuminate target surfaces. Movement of the MI between successive images will enable stereoscopic viewing and production of mosaics that are well focused across the entire frame. The MI will be used to analyze the size and shape of grains in sedimentary rocks to help determine if liquid water was present in the past.

Miniature Thermal Emission Spectrometer (Mini-TES):

• This is a compact infrared spectrometer designed to determine the mineralogy of rocks and soils from a distance by measuring their patterns of thermal radiation. It will also take spectra from the atmosphere of Mars to provide information on dust, water vapor, and temperature. Mini-TES is located in the body of the rover at the base of the Pancam Mast Assembly. The Pancam Mast holds a viewing port with a scan mirror at the same level as the Panoramic Camera assembly, 1.3 m above the ground. Light goes through the viewing port, reflects off the scan mirror and enters the mast, which is built like a periscope, reflecting the light down to a telescope at the base of the mast and on to the spectrometer.
• Mini-TES is based on a Michelson interferometer design which covers the wavelength range from 5-29 µm (2000-345 cm-1) with a scan resolution of 10 cm-1. The field of view can be alternated between 8 and 20 mrad. The mast can turn a full 360° and the scan mirror ranges from -50° to +30° in elevation. These are sequenced to provide a raster image of the scene. The telescope at the base of the mast is a reflecting Cassegrain with a 6.35 cm mirror and a focal ratio of f/12.
• The approximately collimated beam is fed from the telescope to the 980-nm interferometer which generates interference fringes. The instrument uses a single un-cooled deuterated triglycine pyroelectric detector. A signal-to-noise ratio of 450 or better will result from co-addition of two observations. An internal (inside the head of the Pancam Mast Assembly) and external (on the rover deck) targets are also available to provide calibration between or during image scans. The mini-TES will operate primarily during mid-day (between 10 A.M. and 3 P.M. local time), but may also operate at night to obtain diurnal cycle temperature information.

Mossbauer Spectrometer (MB):

• This is designed specifically to study iron-bearing minerals. The sensor head for the MB is mounted on the end of the rover arm, or instrument deployment device. The arm can place the sensor head directly on a sample to be studied. A single measurement takes about 12 hours. The electronics board for the MB, with a mass of about 0.14 kg and a volume of 16x10x2.5 cm is contained in the warm electronics box in the body of the rover. The MB was built by the Mossbauer Group at Johannes Gutenberg University.
• The sensor head has a mass of about 0.41 kg and a volume of about 9.0x5.0x4.0 cm and contains a 57Co/Rh source to illuminate the target. The source is moved at a known velocity by a Mossbauer drive and backscattered radiation is measured by gamma- and x-ray detectors in the sensor head. The gamma signals are binned by source velocity. The mineralogical information on the target is given by hyperfine splitting of 57Fe nuclear levels. There are five analog detector channels which are analyzed by discriminators for 14.41 keV and 6.4 keV peaks.
• Mossbauer spectra for the two energies are sampled separately, each consisting of 512 x 3-byte integers. Calibration spectra will be taken during sampling using a reference channel in the instrument. A magnetite-rich calibration target will also be mounted on the rover where it can be directly viewed by the MB. The 12-hour measurement run will be timed to include daytime maxima and nighttime minima temperatures to use the temperature dependent behavior of the Mossbauer parameters to help determine the nature of the iron-bearing phases.

Alpha Particle X-ray Spectrometer (APXS):

• This is designed to determine the elemental chemistry of rocks and soils on the surface of Mars. The APXS sensor head is mounted on the rover arm, or instrument deployment device, and is operated by placing the sensor directly on the sample. The APXS works by exposing the target to energetic alpha particles and X-rays emitted by a radioactive 244Cm source in the sensor head and measuring the energy spectrum of backscattered alpha particles and emitted X-rays from the target. Using this technique abundances of all rock-forming elements except hydrogen can be measured.
• The APXS sensor head contains six 244Cm sources with a total source strength of 30 mCi. Each source is covered with 3 µm aluminum foils that reduce the energy of the emitted alpha particles from 5.8 MeV to 5.2 Mev, which serves to suppress the atmospheric carbon dioxide background. Collimators in front of the sources give a field of view 38 mm in diameter at 29 mm working distance. Six alpha detectors surround the source and inside these is a high-resolution silicon drift X-ray detector. A pair of doors protects the sensor from martian dust. When the sensor head is put in place, the doors swing open to expose the source and detectors. The instrument electronics are housed in the warm electronics box.
• The X-ray detector can measure major elements such as Mg, Al, Si, K, Ca, and Fe and minor elements including Na, P, S, Cl, Ti, Cr, and Mn. The FWHM of the x-ray detector is 160 eV at 6.4 keV. The alpha detector is better suited for lighter elements, particularly C and O. FWHM for detections at 5.8 MeV is less than 100 keV. The detection limit is about 0.5 to 1 weight percent. The time for a full measurement is at least 10 hours. The x-ray mode alone takes significantly less time than this. Most data accumulation is planned for nighttime when temperatures are lowest, giving the best spectral resolution.

Rock Abrasion Tool (RAT):

• This is a device containing a grinding wheel designed to remove dust and weathered material from the surface of a rock to expose a fresh surface. The fresh surface, which is more likely to represent the original rock before alteration, can then be studied by the other rover instruments. It is mounted on the rover arm, or instrument deployment device and is placed by the arm against the target rock.
• The RAT is 7 cm in diameter and 10 cm long. It uses two diamond matrix wheels. Each wheel has two teeth which cut out a circular area as the head rotates at high speed. The grinding wheels can also slowly revolve around each other, sweeping the two circular areas over a 4.5 cm diameter cutting region. The wheels can penetrate by fractions of a mm as commanded, creating a hole as deep as 0.5 cm. Penetration into the rock is slow and designed to minimize alteration of the petrologic fabric, chemistry, or mineralogy. Currents and temperatures will be monitored during the grinding operation to infer information on the rock properties. Grinding operations take about 2 hours for a dense basalt.

Magnet Arrays:

• This experiment is designed to gather samples of the magnetic components of martian dust, soil, and rocks to determine their mineralogy and origins. The types of magnetic minerals present on Mars may reveal information on past conditions on the planet.
• There are three Magnet Arrays on each Mars Exploration Rover.
  • One array is mounted on the RAT on the rover arm to collect samples of dust produced during the grinding process. This array consists of four magnets of different strengths, each 0.7 cm in diameter and 0.9 cm thick. The different strengths will allow a range of magnetic materials to be captured and examined by the Panoramic Camera. After examination, the magnets are designed with a temperature-driven retraction device, which slides the magnets into a sleeve each night when temperatures drop, clearing off the magnets for the next set of samples.
  • Another array is mounted on the front of the rover at an angle so that non-magnetic particles will fall off and only magnetic particles will stick to the array. The samples can then be analyzed by the Mossbauer spectrometer and APXS. The array consists of one capture magnet and one filter magnet. The capture magnet is a strong magnet designed to attract all iron-containing dust while the weaker filter magnet is designed to capture only the most magnetic dust. These magnets are each contained within an aluminum disk 4.5 cm in diameter.
  • The third magnet is a sweep magnet mounted on top of the rover deck in view of the Pancam so the material collected can be imaged at high resolution. The sweep magnet is a thin-walled magnetic tube magnetized along its symmetry axis. It is strong enough to deflect the paths of wind-transported magnetic particles, which will accumulate in a narrow ring corresponding to the tube. The central surface inside the ring will collect non-magnetic particles, and at greater radial distances both magnetic and non-magnetic particles will accumulate.

Engineering Cameras (Hazcoms and Navcoms):

• There are two types of Engineering Cameras on the Mars Exploration Rover, the Hazard Avoidance Cameras (Hazcoms) and the Navigation cameras (Navcoms).
• There are four Hazcoms, two mounted on the lower front of the rover and two on the lower rear. They are black and white visible light cameras with a field of view of about 120x120°. The cameras view the terrain up to 3 m in front of and behind the rover to detect any obstacles in the path of the rover. The camera output is interperated by software which directs the rover to avoid any perceived hazards.
• The two Navcams are mounted on the rover mast as a stereo pair. They take visible light panoramic images with a 45x45° field of view to assist in navigation of the rover, and also assist the hazard avoidance imaging by giving a higher perspective of the ground.

Craft Data

MESSENGER: MErcury Surface, Space EnviroNment, GEochemistry and Ranging

No craft has visited Mercury since Mariner 10 in 1975. Since then, many questions about Mercury have been raised, and it is hoped that this mission will answer some of them. This mission is designed to study the characteristics and environment of Mercury from orbit. Specifically, the objectives are to study the surface composition, geologic history, core and mantle, magnetic field, tenuous atmosphere, and to search for water ice and other frozen volatiles at the poles over a nominal orbital mission of one Earth year (365 days).

The craft was launched on August 3, 2004, at 6:15:56 UT (2:15:56 A.M. EDT) on a Delta 7925H (a Delta II Heavy launch vehicle with nine strap-on solid-rocket boosters). The spacecraft was injected into solar orbit 57 minutes later. The solar panels were then deployed and the spacecraft began sending data on its status. One year after launch, on August 2,2005, MESSENGER flew by Earth at an altitude of 2347 km. On December 12, 2005, at 11:30 UT, MESSENGER fired its large thruster for 524 seconds, changing the spacecraft velocity by 316 m/s and putting it on course for its October 24, 2006, Venus flyby at an altitude of 3612 km. There will be another Venus flyby on June 6, 2007, at an altitude of 300 km.

The first of three Mercury flybys, all at 200 km altitude, will be on January 15, 2008, the second will be on October 6, 2008, and the third on September 30, 2009. There will also be five deep space maneuvers. Data collected during the Mercury flybys will be used to help plan the scientific campaign during the orbital phase. Mercury orbit insertion will take place on March 18, 2011, requiring a change in velocity of 0.867 km/s.

The nominal orbit is planned to have a periapsis of 200 km at 60° N latitude, an apoapsis of 15,193 km, a period of 12 hours and an inclination of 80°. The periapsis will slowly rise due to solar perturbations to over 400 km at the end of 88 days (one Mercury year) at which point it will be readjusted to a 200 km, 12 hour orbit via a two burn sequence. Data will be collected from orbit for one Earth year, and the nominal end of the primary mission will be in March 2012.

Global stereo image coverage at 250 m/px resolution is expected. The mission should also yield global composition maps, a 3-D model of Mercury's magnetosphere, topographic profiles of the northern hemisphere, gravity field to degree and order 16, altitude profiles of elemental species, and a characterization of the volatiles in permanently shadowed craters at the poles.

Mars Reconnaissance Orbiter

This mission, called MRO for short, is an orbiter to study the martian surface. The primary objectives are to study the weather and climate of Mars and to help identify landing sites for future missions. Besides a visual imager with a resolution better than one meter (three feet), the orbiter will carry a spectrometer to analyze the surface composition. Provided by the Italian Space Agency, a shallow subsurface sounding radar (SHARAD) will be included to search for underground water. The orbiter will also be closely tracked to give information on the gravity of Mars.

MRO was launched on August 12, 2005, at 11:43 UT (7:43 A.M. EDT) from the Kennedy Space Center. It fired its main rockets on August 30, 2005, for a main course correction, and the rockets will not be used again until it reaches Mars. It will reach Mars on March 10, 2006, and it will spend six months aerobraking to reach an eventual polar orbit of 255x320 km (160x200 miles). The planned science mission will last approximately one martian year (687 days), from November 2006 through November 2008.

After it's main mission, the orbiter will serve as a communications relay for future missions. This will be the first part of an "interplanetary internet" to be used for communications back and forth between Earth and Mars to be used by international spacecraft. The mission will also test an experimental optical navigation camera that will serve as a high-precision interplanetary "lighthouse" to guide incoming spacecraft nearing Mars.

Venus Express

This mission owes its existence to the ESA Mars Express mission. The ESA wanted to reuse the design of Mars Express as well as have it ready to launch in 2005. Out of all the proposals, Venus Express was chosen in 2002 because it would make use of the spare instruments developed for Mars Express and Rosetta to achieve the main science objectives - studying the atmosphere in detail.

This will be the ESA's first mission to Venus, with the USA and Russia being the only two countries / space programs to have sent craft to Venus. This probe will be the first craft to perform a global investigation of the Venusian atmosphere. It will also be the first craft to study Venus' surface using the recently discovered "visibility windows" in the infrared part of the spectrum.

Venus Express was launched on a Soyuz-Fregat launcher from Baikonur Cosmodrome in Kazakhstan on Wednesday, October 26, 2005, at 06:33 CEST (04:33 GMT, 10:33 local time). Its journey to Venus will last 153 days, when it will be captured by Venus' gravity in April 2006, and take five days to achieve its planned elliptical orbit of 250x66,000 km (155x41,000 miles). The mapping mission should last for about two Venus days (~500 Earth days), and it may be extended depending upon the craft's health.

The 1240 kg mass spacecraft was developed for ESA by a European industrial team led by EADS Astrium with 25 main contractors spread across 14 countries. Initial Fregat upper-stage ignition took place 9 minutes into the flight, maneuvering the spacecraft into a low-earth parking orbit. A second firing, 1 hour 22 minutes later, boosted the spacecraft to pursue its interplanetary trajectory.

When making its closest approach, Venus Express will face far tougher conditions than those encountered by Mars Express on nearing the Red Planet. For while Venus's size is indeed similar to that of the Earth, its mass is 7.6 times that of Mars, with gravitational attraction to match. To resist this greater gravitational pull, the spacecraft will have to ignite its main engine for 53 minutes in order to achieve 1.3 km/sec deceleration and place itself into a highly elliptical orbit around the planet. Most of its 570 kg of propellant will be used for this maneuver.

Though the craft is used from many of the spare components of Mars Express, Venusian environmental conditions are very different to those encountered around Mars. Solar flux is four times higher and it has been necessary to adapt the spacecraft design to this hotter environment, notably by entirely redesigning the thermal insulation. Whereas Mars Express sought to retain heat to enable its electronics to function properly, Venus Express will in contrast be aiming for maximum heat dissipation in order to stay cool.

To accomplish its science studies, it has seven instruments onboard: Three are flight-spare units of instruments already flown on Mars Express, two are from comet-chaser Rosetta and two were designed specifically for this mission.

The PFS high-resolution spectrometer will measure atmospheric temperature and composition at varying altitudes. It will also measure surface temperature and search for signs of current volcanic activity. The SPICAV/SOIR infrared & ultraviolet spectrometer and the VeRa instrument will also probe the atmosphere, observing stellar occultation and detecting radio signals; the former will in particular seek to detect molecules of water, oxygen and sulphuric compounds thought to be present in the atmosphere. The Virtis spectrometer will map the various layers of the atmosphere and conduct multi-wavelength cloud observation in order to provide images of atmospheric dynamics.

Assisted by a magnetometer, the ASPERA 4 instrument will analyze interaction between the upper atmosphere and the solar wind in the absence of magnetospheric protection such as that surrounding the Earth (for Venus had no magnetic field). It will analyze the plasma generated by such interaction, while the magnetometer will study the magnetic field generated by the plasma.

The VMC camera will monitor the planet in four wavelengths, notably exploiting one of the "infrared windows" revealed in 1990 by the Galileo spacecraft (when flying by Venus en route for Jupiter), making it possible to penetrate cloud cover through to the surface. The camera will also be used to monitor atmospheric dynamics, notably to observe the double atmospheric vortex at the poles, the origin of which still remains a mystery.