Sojourner was the small rover that explored Mars during NASA’s Pathfinder mission in 1997.
Pathfinder landed on 4 July 1997 in Ares Vallis, a region selected because ancient floods may have deposited a variety of rocks and soil there. Sojourner communicated through the stationary Pathfinder lander and used a front camera plus scientific instruments to study nearby rocks.
The rover was designed for a seven-sol mission but operated for 83 sols, or Martian days. It traveled about 100 meters and demonstrated technologies for autonomous navigation, airbag landing and low-cost planetary exploration.
Sojourner was named after Sojourner Truth, the nineteenth-century American abolitionist and women’s-rights advocate. It is often confused with Spirit and Opportunity, which arrived on Mars in 2004, or Curiosity, which landed in 2012.