Perseverance will be the fifth rover to arrive on Mars that’s capable of venturing across the surface of another planet. These amazing laboratories on wheels have extended our knowledge of a faraway world. Here’s what they’ve told us so far. The first rover - Sojourner Twenty years after Viking 1 & 2 landed stationary probes on Mars, a third spacecraft finally reached the planet, but this one could move. On July 4, 1997, NASA’s Pathfinder literally bounced onto the Martian surface, safely enclosed in a giant set of airbags. Once stable, the lander released the Sojourner rover. See the Sojourner probe from Pathfinder’s viewpoint.