Soviet Mars program

Spacecraft

The first Soviet attempts to send a probe to Mars were the two Mars 1M spacecraft, each with a mass of about 650 kg, launched in 1960; both failed to achieve orbit and were dubbed Marsnik by Western media. Mars 1, launched in 1962, failed en route to Mars. Two other launches around the same time, Mars 2MV-4 No.1 and Mars 2MV-3 No.1, were 900 kg spacecraft but both failed to leave Earth orbit due to upper-stage problems. Mars 2M No.521 and Mars 2M No.522, known in the West as Mars 1969A and B, were heavier spacecraft with masses of 5 t, launched by Proton-K rockets and consisting of orbiters; both were destroyed during launch. The Mars 4M spacecraft—Mars 2 and Mars 3—were identical spacecraft, each with an orbiter and an attached lander, and became the first spacecraft to reach the surface of Mars. The orbiters' primary scientific objectives included imaging the Martian surface and clouds, determining temperature, studying topography, composition, and physical properties of the surface, measuring atmospheric properties, monitoring the solar wind and magnetic fields, and acting as communications relays for the landers. Both landers carried a small Mars rover, PrOP-M, designed to move on skis while connected by a 15-meter umbilical; two small metal rods provided autonomous obstacle avoidance, and each rover had a densitometer and dynamic penetrometer to test soil density and bearing strength. Neither rover saw action due to the landers' demise. The Mars 2 and 3 orbiters returned a large volume of data from December 1971 to March 1972, with transmissions continuing through August; they completed 362 orbits (Mars 2) and 20 orbits (Mars 3) by August 22, 1972, sending back 60 pictures that enabled surface relief maps and information on Martian gravity and magnetic fields. The Mars 3MS were orbiter-only spacecraft launched three times between 1971 and 1973.