Other Mars Missions

Mariner | Pioneers | Voyagers | Other Mars Missions | Galileo

Overview

Mars has always been held as more Earth -like than any other planet in the known solar system. Since "canals" were first seen in the red planet (now known not to be canals), humans have held that life may exist on Mars. That is why it is fast becoming one of the most extensively studied planets. In fact, you can even find the current weather of Mars, as well as its position relative to Earth at the Mars Today home page.

Past Exploration

The Mariner project was the first to send craft to Mars. See its page for information.

The Viking 1 craft was launched from Florida's Cape Canaveral on August 20, 1975. Its main mission was to study the air, surface, and to search for micro-organisms in Mars's soil. The lander, also containing two robot explorers, set down on the western slopes of Chryse Planitia on July 20, 1976. It did not find the evidence needed to support life on Mars, but its findings are still being debated by a few people. Viking 1 also sent back color panoramas of Mars, and showed that the sky was pinkish due to all of the red dust (rust) in the air, and that there was red soil and red boulders as far as it could see. Also sent back were pictures of canyon systems and what looked like dry river beds. The last data was collected on November 11, 1982. After 6.5 unsuccessful months of attempted contact, the mission was put to an end on May 21, 1983.

Viking 2 was launched on September 9, 1975, and landed on Mars on September 3, 1976 in Utopia Planitia. It carried out the same mission as the Viking 1, but it also had a working seismometer which recorded one Marsquake, possibly hinting at active plate tectonics (the forces that make mountains, valleys, and the continents move on the Earth).

21 years later, on July 4, 1997, after seven months of traveling through space, the Pathfinder probe landed on Mars in Ares Villis. When it was between 6-10 km (3.6-6 miles) above ground zero, it let out a parachute which abruptly slowed its descent. As it was about to reach the ground, it inflated air bags to help soften the landing; it still bounced approximately 16 times.

It was three hours before the Martian sunrise when it landed. The probe quickly deflated the air bags, then opened up like a flower - each "petal" being a solar panel to generate power. Four hours later, it broadcast a signal to Earth. Then, on July 6, a small rover less than three feet long rolled out and onto the Martian surface, becoming the first rover on Mars. The rover's name, Sojourner, was given by 13-year-old Valerie A. of Bridgeport, Connecticut, in early 1996, in a contest that had been sponsored by NASA in order to increase public support for the mission.

Sojourner contained an on-board camera with which it could relay signals back to the base and then have them relayed to Earth. If scientists wanted Sojourner to explore a particular part of the region, then they signaled it through the base. There was a time delay of 7-22 minutes because the distance between Mars and Earth is so large.

Sojourner used laser beams much as an insect uses feelers, and if confronted with an obstacle, it would just keep bumping into it until it got across. Sojourner's main purpose was to determine the chemical composition of Martian rocks, looking for carbonous compounds which could indicate life.

One discovery that the Pathfinder made, combined with data from the Viking crafts, is that Mars has a crust, mantle, and core, with the heavier elements nearer to the center. Such a structure had been guessed at, but now scientists have direct evidence of such layering.

A discovery that Sojourner made (early August 1997) was finding evidence that winds up to 200 kph (125 mph) used to blow across the region where they landed. Evidence was found when examining rocks and finding that they had been sandblasted in several places. Such sand blasting could have only been formed by fast winds whipping sand around.

Pathfinder's last transmission to Earth was on September 27, 1997. Ground receivers haven't heard routine signals since October 6, 1997. After a month of attempted contact, NASA stopped on November 4, 1997. NASA now believes that its batteries have died, two months after its 30-day expected life. Without batteries to keep it warm, the craft probably stopped functioning. Sojourner, programmed to return to Pathfinder if no signal has been received for five days, probably returned to it.

The site has since been named the "Carl Sagan Memorial."

Current Exploration

Launched on November 7, 1996, the Mars Global Surveyor (MGS) is currently orbiting Mars. With sophisticated laser equipment, it has mapped Mars, circling the planet about once every two hours. It bounces a beam of laser light off Mars at a rate of ten per second, and then it records how long it takes the light to return to the craft. It works like sonar that ships use to map the ocean floor on Earth. MGS Camera images are available online at http://www.msss.com/moc_gallery/.

Unfortunately, the main Mars mapping mission was postponed until March of 1999, due to a damaged solar panel. When the MGS arrived at Mars in September of 1997, it was supposed to continually dip down into the Martian atmosphere until the resistance of the atmosphere slowed the craft down and brought it into a circular orbit nominal for mapping. However, in early October 1997, the craft encountered dense air which caused a solar panel to flip back and forth. NASA suspended aero-braking for three weeks, after which NASA adopted a plan which brought the craft less deep into Mars' atmosphere on November 7, 1997. This prevented the solar panel from breaking off or being damaged.

One discovery (early October 1997) is that Mars has over eight "magnetic patches" that might be the remnants of an ancient magnetic field. The patch's axes though, are pointing in all different directions. The strongest field is only about 1.3% that of Earth's magnetic field. The field fragments could have been formed when iron-rich rocks rose at different times, and then became trapped in the surrounding rocks. This model shows that each field fragment is a picture of what Mars' magnetic field looked like at various times.

Another discovery (taken October 1997, analyzed early March 1998) is that above 50° latitude (about the upper half of the northern hemisphere), Mars is practically flat, with no hills or valleys. This is leading scientists to theorize that oceans may have flattened it, for the only areas on Earth that are this flat are at the bottoms of deep oceans. If this is true, further mapping may reveal a shoreline. After the MGS's major mapping mission is completed, it will be used as a relay station for about three years by other spacecraft in orbit and on Mars.