Sojourner

The first rover to successfully operate on Mars. Part of the Mars Pathfinder mission, this 23-pound, microwave-oven-sized robot demonstrated that low-cost, semi-autonomous rovers could conduct real science on another planet. Sojourner analyzed rocks and soil with its Alpha Proton X-ray Spectrometer and navigated hazards using a laser-based system. It operated for 83 days — 12 times its design life — and proved the template for every Mars rover since. Small, capable, resilient.