The primary objective was to demonstrate a low-cost method of delivering a set of science instruments and a free-ranging rover to the surface of Mars. The 23-pound Sojourner rover conducted technology experiments and served as an instrument deployment mechanism.

The science objectives were to:

•

Investigate the Martian atmosphere, surface metrology and geology

•

Characterize surface features

•

Analyze the elemental composition of rocks and soil at the landing site

•

Monitor atmospheric conditions as they varied over the course of the mission with photographic and analytical instruments

Launched on December 4, 1996, Pathfinder arrived at Mars on July 4, 1997.  Slowed in its descent through the thin Martian atmosphere by a parachute, it was in free-fall the last few hundred feet and bounced over the Martian surface on its inflated airbags like a giant beach ball.  Once it rolled to a stop, the airbags deflated, the petals of the lander opened,
and the rover descended to begin exploring and analyzing nearby rocks.

Mars Pathfinder set ambitious objectives and surpassed them.  The lander, formally named the Carl Sagan Memorial Station following its successful touchdown, captured over 16,500 images, while the rover snapped 550 pictures.  The mission performed more than 15 chemical analyses of rocks and soil and returned extensive data on winds and other aspects of weather.  The observations suggest that early Mars may once have been more Earth-like than it is today, with liquid water on its surface and a thicker atmosphere.

The engineering design far exceeded expectations.  The mission functioned on the Martian surface for about three months, well beyond the planned lifetimes of 30 days for the lander and seven days for the rover, coming to an end on Sept. 27, 1997.

More detailed mission results can be found in the December 5, 1997 issue of Science and in abstracts presented at the 29th Lunar and Planetary Science Conference in March 1998. For further information, visit the National Space Science Data Center, NASA's permanent archive for space science mission data.

Stamp of Approval
On December 10, 1997, the U.S. Postal Service paid tribute to NASA's Mars Pathfinder mission with a $3 Priority Mail stamp featuring one of the first images transmitted to Earth.  The Postmaster General said the Pathfinder mission is one of the most significant achievements in the history of America's space program, and that the stamp is a reminder of the unmatched ingenuity that leads the world in space exploration.

Rover Recognition
The Mars Pathfinder Sojourner Rover, the first to explore another planet, was inducted into the Robot Hall of Fame in 2003 for the revolutionary feat it accomplished on the Martian surface.  For the first time, a thinking robot equipped with sophisticated laser eyes and automated programming reacted to unplanned events on the surface of another planet.  A hazard avoidance system set the rover apart from all other machines that previously explored space.  It paved the way for the successful Spirit and Opportunity rovers that have been exploring Mars since 2004 and the next rover, Curiosity, a sophisticated mobile laboratory that will arrive at Mars in 2012.