Mars Pathfinder Lands
NASA's Mars Pathfinder lander and Sojourner rover landed, becoming the first rover to operate on another planet
July 04, 1997
A New Way to Explore Mars
NASA's Mars Pathfinder spacecraft landed on the surface of Mars on July 4, 1997 — American Independence Day. The landing used a novel airbag system: the probe bounced across the Martian surface inside a cocoon of inflatable bags before rolling to a stop. Pathfinder then deployed the Sojourner rover, a small six-wheeled vehicle about the size of a microwave oven. It was the first Mars rover in history and the first time a mobile vehicle had explored another planet's surface.
What Sojourner Found
Sojourner traveled about 330 feet over its 83-day mission, analyzing rocks and soil with an instrument called the Alpha Proton X-ray Spectrometer. Scientists found evidence of ancient floods that had deposited rounded pebbles and boulders across the landing site, suggesting Mars once had liquid water on its surface. The rover sent back more than 550 images, and Pathfinder transmitted 16,500 photos and 8.5 million weather measurements before contact was lost in September 1997.
Pathfinder's Lasting Impact
Mars Pathfinder proved that a small, low-cost mission could conduct meaningful science on another planet. Its total cost of $280 million was a fraction of previous Mars missions. NASA called it a "faster, better, cheaper" success. The mission inspired the later Spirit, Opportunity, Curiosity, and Perseverance rovers, each increasingly sophisticated. Pathfinder also became one of the first major scientific events to be widely followed on the internet, with NASA's website crashing under record traffic during the landing. Use our date calculator to mark the anniversary.