Hitching a ride on the Mars Pathfinder mission, the Sojourner rover arrived at the Red Planet on July 4, 1997. The mission was designed to demonstrate a low-cost method for delivering a set of science instruments to Mars, and served as the foundation for the Mars rovers of today.
Pathfinder landed the rover using an air bag landing system and innovative petal design, which have been used since in various incarnations to land other rovers on the Red Planet. Sojourner spent 83 days of a planned seven-day mission exploring the Martian terrain, snapping photographs and taking chemical, atmospheric and other measurements.
The lander, formally named the Carl Sagan Memorial Station following its successful touchdown, and the rover, named after civil rights pioneer Sojourner Truth, both outlived their design lives — the lander by nearly three times, and the rover by 12 times. Mars Pathfinder returned 2.3 billion bits of information, including more than 16,500 images from the lander and 550 images from the rover, as well as more than 15 chemical analyses of rocks and soil and extensive data on winds and other weather factors.
This panoramic view of Pathfinder’s Ares Vallis landing site shows Sojourner rover is the distance. The Mars Pathfinder mission completed the last successful data transmission cycle at 6:23 a.m. EDT on Sept. 27, 1997.