Mars Polar Lander. Computer illustration of the Mars Polar Lander onboard its rocket during launch, with insets showing the structure of the lander. This lightweight spacecraft, seen in the upper part of the rocket, was built to study the soil and weather on Mars. It was launched on 3rd January 1999 and carried several imaging systems and a robot arm for the collection of soil samples for on-board analysis. Also on the mission were two microprobes. These were designed to hit the surface and bury small probes in the Martian soil to look for water in the deeper layers. Contact with the spacecraft was lost just before its expected landing on 3rd December 1999.