Cute as a Star Wars droid, the Mars rover named Sojourner was an overnight international hero during its three months in the spotlight. Its odometer stopped at about 110 yards (101 meters) when the last data transmission was received on September 27, 1997. But prior to falling silent, the six-wheeled, 23-pound (10-kilogram) buggy sent back images and information that brought humankind closer than ever to determining for certain the past presence of stable water on Mars.

Traveling at two feet (0.6 meter) per minute, the rover was never meant to be a speed demon. Its slow-but-steady pace enabled it to maneuver over and around rocks and maintain traction on the Martian soil, ensuring the safety of its scientific experiments.

The rover, named after abolitionist Sojourner Truth, was designed to give “ground truth” on its Mars sojourn, surface data to be used for interpreting information gathered by yet-to-be-launched Mars orbiters.

NASA scientists liked to call the U.S. $25 million rover an interplanetary geologist. Its alpha-proton x-ray spectrometer (APXS) analyzed the elemental composition of rocks and soils. Twin black-and-white cameras mounted on the front took stereo images, and a single color camera on the back was used for close-up pictures.

Because radio signals took some ten minutes to reach Mars, the rover’s primary designated driver, Brian Cooper, couldn’t run Sojourner like a kid’s remote control car. Confirmation that everything went as planned often didn’t come for hours after the initial command from his computer. “It was kind of frustrating...but a lot of fun,” said Cooper.