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More than 35 million miles from Earth, a pair of 400-pound remote-controlled vehicles were stuck. Mars exploration rovers and landed on the Red Planet in 2004, equipped with well-designed navigation systems. The mission was designed to last for 90 Martian days, but because the rovers were behaving so well, their exploring and cataloguing of Mars continued.

Suddenly, movement came to a halt.

NASA researcher (S’87, CS’96) knew what to do. His experience at Carnegie Mellon pointed him to global path selection software developed by (S’84, CS’90), Carnegie Mellon research professor and current director of Â鶹´å’s .

Field D*, an algorithm, similar to ones programmers use to control drones in video games, can compute on the fly in unknown terrain, continuously adding data to plot the best path for a vehicle. Stentz and former student (CS’04, ’06) built a compact version of the software they developed to work on the tiny 20 MHz CPU used by the solar-powered rovers. Maimone’s team uploaded it directly to Spirit and Opportunity and the mission resumed, completing a series of long-range trips, including a 12-mile traverse from Victoria Crater to Endeavour Crater.

Today, NASA has a new, larger rover sniffing out water and microbes on Mars. Curiosity touched down safely in August with Field D* at the ready. —Shannon Gazze