The Mars Observer spacecraft, also known as the Mars Geoscience/Climatology Orbiter, was a robotic space probe launched by NASA on September 25, 1992 to study the Martian surface, atmosphere, climate and magnetic field. During the interplanetary cruise phase, communication with the spacecraft was lost on August 21, 1993, 3 days prior to orbital insertion. Attempts to re-establish communication with the spacecraft were unsuccessful.