Launched December 4, 1996, Pathfinder has been one of the great success stories from NASA's recent history. After the spacecraft approached the planet at 22,000 miles per hour, its landing sequence - which culminated in Pathfinder's bouncing across the surface of the red planet on July 4, 1997, like a beach ball at an Independence Day picnic - was straight out of science fiction. Even more fascinating was the mission's firsthand, and first-ever, live delivery of surface-level photographs, and the wanderings of what Golombek likes to call its "one-foot-tall geologist" - the Sojourner Rover.
Pathfinder also took enough 3-D pictures to allow the assembled crowd, with glasses in place, to accompany Golombek on a walk along the surface of Mars. "People always ask me, could life have started on Mars?" he said during the visual tour. "To look for the answer to that, you go to the rocks."
Pathfinder didn't deliver any conclusive evidence of life, but the mission added plenty of new data to the debate. The team analyzing Pathfinder's data did not find water, but it did find sand and a piece of conglomerate, a rock type made of smaller fragments held together in a matrix of finer materials. On Earth, Golombek said, both these things are evidence of water once having existed in a location, even if it's no longer there.
Pathfinder, in fact, helped discover many links between Earth and Mars. Martian rocks, Golombek said, "are basically the same as continental rocks on Earth." And Mars also has dust devils. "Just like in Twister," he said, "only without the cows."