Soviet Mars Programme Orbiter-Lander Probes

The Mars probe program conducted by the Soviet Union sent a series of uncrewed spacecraft toward Mars beginning in the 1960s, several of which combined an orbiter bus with an attached lander capsule in a single launch. Mars 2 and Mars 3, both launched in May 1971 on Proton-K rockets with a Blok D upper stage, were identical spacecraft of this orbiter-lander design, each carrying an orbiter derived from the Venera 9 bus together with a descent module intended to reach the Martian surface. The Mars 2 lander crashed during descent, becoming the first human-made object to reach Mars, while the Mars 3 lander achieved the first successful soft landing on the planet in December 1971, though it transmitted for only about twenty seconds before falling silent. Both orbiters continued to return data and images of the Martian surface for months afterward. As paired orbiter-and-lander spacecraft built to one design and launched within days of each other, Mars 2 and Mars 3 anchor this class within the wider Soviet Mars program.