The Mars program was a series of Mars unmanned landers and orbiters launched by the Soviet Union in the early 1970s.
The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander. Although Mars 2 crashed, the Mars 3 mission was the first spacecraft to touch down on Mars. They were launched by Proton-K rockets with Blok D upper stages.
Mars 3 Orbiter
The orbiter suffered from a partial loss of fuel and did not have enough to put itself into a planned 25 hour orbit. The engine instead performed a truncated burn to put the spacecraft into a long 12 day, 19 hour period orbit about Mars.
The orbiter primary scientific objectives were to image the Martian surface and clouds, determine the temperature on Mars, study the topography, composition and physical properties of the surface, measure properties of the atmosphere, monitor the solar wind and the interplanetary and Martian magnetic fields, and act as communications relays to send signals from the landers to Earth.
The Mars 3 orbiter sent back a large volume of data covering the period from December 1971 to March 1972, although transmissions continued through August. It was announced that Mars 3 had completed their mission by 22 August 1972, after 20 orbits. The probe, combined with Mars 2, sent back a total of 60 pictures. The images and data revealed mountains as high as 22 km, atomic hydrogen and oxygen in the upper atmosphere, surface temperatures ranging from -110 C to +13 C, surface pressures of 5.5 to 6 mb, water vapor concentrations 5000 times less than in Earth’s atmosphere, the base of the ionosphere starting at 80 to 110 km altitude, and grains from dust storms as high as 7 km in the atmosphere. The images and data enabled creation of surface relief maps, and gave information on the Martian gravity and magnetic fields.
1971-05-28 15:26:30 UTC
Proton K with Blok D
Orbital Insertion Date
Apoapsis 211400 km
Periapsis 1500 km
Orbital Period 12.79 d
May 28, 1971 to August 22, 1972