1999: NASA loses radio contact with the Mars Polar Lander moments before the spacecraft enters the Martian atmosphere. The cause of the communication loss is not known. However, NASA's Failure Review Board would conclude that the most likely cause of the mishap was a software error that incorrectly identified vibrations, caused by the deployment of the lander's stowed legs, as surface touchdown. The resulting action by the spacecraft would have been the shutdown of the descent engines, while the spacecraft was still likely 40 meters above the surface, causing it to crash into the Martian surface. The lander is seen here in October 1998, a few months before its January 1999 launch.