1999: Mars Polar Lander
A partner craft to the Mars Climate Orbiter, the Mars Polar Lander was similarly ill-fated. Launched in early 1999 and reaching the Red Planet that December, the plan was for the lander to alight on the Martian south pole and look for water ice, which would give clues as to whether the planet could ever have hosted life.
After the lander entered the Martian atmosphere, communication ceased. NASA looked for signs of the lander for over a month but found nothing. Three months later, in March 2000, an independent investigation concluded that malfunctioning sensors made the doomed lander think it was already on the ground when it was actually still descending. This would’ve caused the lander’s engines to shut down early and the craft to meet the dirt with a fatal crunch.
