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Mars Pathfinder

Mars Pathfinder mission graphic

Phase: Past

Launch Date: December 04, 1996

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Mars Pathfinder launched December 2, 1996 and arrived on the surface of Mars on July 4, 1997. The mission was an engineering demonstration of key technologies and concepts for use in future missions to Mars; it also delivered science instruments to the surface of Mars to investigate the structure of the martian atmosphere, surface meteorology, surface geology, form, and structure, and the elemental composition of martian rocks and soil. A small, 10-kilogram (22-pound) rover was carried on the Pathfinder and became the first rover ever to explore the Martian surface.

Pathfinder view of the martian surface

Twin Peaks on Mars

The Twin Peaks are modest-size hills to the southwest of the Mars Pathfinder landing site. They were discovered on the first panoramas taken by the IMP camera on the 4th of July, 1997, and subsequently identified in Viking Orbiter images taken over 20 years ago. The peaks are approximately 30-35 meters (-100 feet) tall. North Twin is approximately 860 meters (2800 feet) from the lander, and South Twin is about a kilometer away (3300 feet). The scene includes bouldery ridges and swales or "hummocks" of flood debris that range from a few tens of meters away from the lander to the distance of the South Twin Peak.

The second of the Discovery Program missions, development of the spacecraft and free-ranging surface rover was limited to 3 years and $150 million. No orbiter was used to scout a landing site and deliver the lander to the surface. Rather, the microrover, named Sojourner, was encased in a self-righting tetrahedral lander, which, in turn, was encapsulated in an aeroshell designed to withstand atmospheric entry.

From Viking photos, a landing site had been pre-selected: an ancient flood plain in Mars' northern hemisphere called Ares Vallis.  The site has been named The Carl Sagan Memorial Station in honor of the late Dr. Carl Sagan.  Slowed in its descent by a system of parachutes and retro-rockets, the lander/rover then fell freely the last few hundred feet, bouncing on its inflated airbags over the Martian surface like a basketball. The airbags deflated, the petals of the lander opened, and the rover descended and began exploring and analyzing nearby rocks.

The engineering design far exceeded expectations.  The lander operated for nearly three times its design lifetime of 30 days, and the Sojourner rover operated 12 times its design lifetime of seven days.

Mars Pathfinder returned more than 16,000 images from the lander and 550 images from the rover and extensive data on winds and other weather factors was collected.  The AXPS (Alpha Proton X-ray Spectrometer) instrument performed chemical analyses of several rocks and soils.  The analyses showed a diversity of rock types at the landing site and generally higher silica contents than martian meteorites.  The soil chemistry of the landing site was similar to that found at the Viking 1 and 2 sites.  Martian dust was discovered to be very fine, with a mean size of just one micron, and to include magnetic particles. Evidence of wind abrasion of rocks and dune-shaped deposits was also found, indicating the presence of sand-sized particles.

The last communication from the spacecraft was received on 27 September 1997, and it was officially declared dead on 10 March 1998.

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