What was the name of the first successful Mars rover?

The first successful Mars rover was Sojourner. It reached Mars aboard NASA's Mars Pathfinder mission on July 4, 1997, becoming the first wheeled vehicle to operate on a world beyond Earth and the Moon.

Sojourner was a small, six-wheeled experimental rover built by NASA's Jet Propulsion Laboratory. It explored the Ares Vallis channel near the Pathfinder lander, examining rocks and soil with cameras and an Alpha Proton X-ray Spectrometer. The mission tested technologies such as autonomous obstacle avoidance and inexpensive airbag-assisted landing.

The rover was designed to operate for only a few Martian days, but remained active for 83 sols—about 85 Earth days—and traveled just over 100 metres. Communication ended in September 1997 after the Pathfinder lander stopped responding.

Sojourner is sometimes confused with Spirit, Opportunity, or Curiosity, which arrived later. Its name honors Sojourner Truth, the 19th-century American abolitionist and women's-rights advocate.