NASA’s Mars Pathfinder mission landed its Sojourner rover on Mars in 1997.
The Pathfinder lander reached Mars on 4 July 1997, landing in Ares Vallis. Sojourner then drove onto the surface and became the first successful wheeled rover to operate on another planet. The mission demonstrated comparatively inexpensive landing and surface-navigation technologies.
Sojourner weighed about 10.5 kilograms and used six wheels. It examined rocks and soil near the lander, while Pathfinder studied the atmosphere and weather. The mission was designed to last seven Martian days but operated for much longer, returning substantial scientific and engineering data.
Pathfinder is distinct from later missions such as Spirit, Opportunity, Curiosity, and Perseverance. Its landing system used airbags, allowing the spacecraft to bounce and roll across the surface before coming to rest. That approach was not used for the larger later rovers.