The Lunokhod 2 rover was the last and most advanced of two unmanned lunar rovers sent by the Soviet Union as part of the Lunokhod program. It landed on the Moon on January 15, 1973 and operated for about 4 months. During this time, it covered 37 km of terrain, including hilly areas and rilles, and sent back 86 panoramic images and over 80,000 TV pictures.
This 37 km journey still holds the record for the longest distance a robotic rover has ever traveled on another celestial body. A number of mechanical tests of the surface, laser ranging measurements, and other experiments were also conducted during its mission