Mars 3 was a robotic space probe of the Soviet Mars program, launched May 28, 1971, nine days after its twin spacecraft Mars 2. The probes were identical robotic spacecraft launched by Proton-K rockets with a Blok D upper stage, each consisting of an orbiter and an attached lander. After the Mars 2 lander crashed on the Martian surface, the Mars 3 lander became the first spacecraft to attain a soft landing on Mars, on 2 December 1971. It failed 20 seconds after landing, having transmitted only a gray image with no details. The Mars 2 orbiter and Mars 3 orbiter continued to circle Mars and transmit images back to Earth for another eight months.