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Mars PathfinderA NASA mission launched Dec. 4 1996 to put a lander and a free-ranging instrument-packed roving vehicle directly onto the planet's surface. The probe landed on Mars on July 4 1997 in the region of the Ares Vallis, an extensive valley-like feature in the northern hemisphere. After landing, Mars Pathfinder released the rover, named Sojourner, which began investigations of the surrounding area. The Pathfinder mission lasted for nearly three months, sending back a wealth of science data about the planet's rocks and soil, its dust and dust storms, its winds and the effects of wind erosion, and possible evidence that water may have flowed on Mars during a warmer past. Pathfinder made its last complete data transmission on Sept. 27. After a month of unsuccessful attempts to communicate with it, mission controllers at the Jet Propulsion Laboratory terminated further efforts to contact the probe on Nov. 4 1997.
The mission successfully demonstrated a low-cost method of delivering scientific instruments to Mars. It was possible to photograph local surface features, and the mission obtained 16 000 images from the lander and 550 from Sojourner.