Launch of Mars Polar Lander

Mars Polar Lander was a NASA spacecraft meant to land near the south polar region of Mars and study its weather, soil and ice. It also carried two small penetrator probes, called Deep Space 2, designed to burrow into the ground. The craft travelled to Mars in the same period as the Mars Climate Orbiter, which had been lost earlier, and expectations were high. All contact was lost as the lander made its descent, and it was never heard from again. A review concluded that the most likely cause was a software fault: vibration from the legs deploying may have been read as touchdown, causing the engines to shut off too early and the lander to fall to the surface. The failure led to reforms in NASA's Mars programme.

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