Which vehicle became the first rover to operate on Mars?

Sojourner became the first rover to operate on Mars.

NASA’s Mars Pathfinder mission delivered Sojourner to the Martian surface on July 4, 1997. The small, six-wheeled rover was designed to demonstrate that a mobile vehicle could travel across another planet and conduct scientific measurements.

Sojourner examined rocks and soil near the landing site, while Pathfinder studied the atmosphere and surrounding terrain. The rover communicated through the lander, which relayed information to Earth.

Spirit and Opportunity arrived later in 2004, and Curiosity landed in 2012. Those rovers were much larger and more capable, but they were not the first to operate on Mars. The Soviet Union’s Mars 2 and Mars 3 missions reached Mars earlier, yet their rovers did not successfully conduct surface operations.