Mission Type: Lander, Orbiter
Launch Vehicle: Proton booster plus upper stage and escape stages; 8K82K + Blok D (Proton-K no. 255-01)
Launch Site: Tyuratam (Baikonur Cosmodrome), USSR; NIIP-5 / launch site 81P
Spacecraft Mass: Orbiter/bus and descent module: about 4650 kg at launch (orbiter/bus: 3440 kg, descent module/lander: 1210 kg)
Spacecraft Instruments: Orbiter: 1) three-component magnetometer; 2) infrared radiometer; 3) radiotelescope; 4) infrared photometer/CO2 absorption strips; 5) ultraviolet photometer; 6) imaging system (two cameras); 7) photometer in visible part of electromagnetic spectrum; 8) cosmic-ray particle detector; 9) energy spectrometer; 10) spectrometer to determine water vapor; and 11) Stereo antenna
Lander: 1) gamma-ray spectrometer; 2) x-ray spectrometer; 3) thermometer; 4) wind velocity recorder; 5) barometer; 6) imaging system (two cameras); 7) penetrometer (on mobile PROP-M); and 8) gamma-ray densitometer (on PROP-M)
Spacecraft Dimensions: Combined orbiter/bus and descent module: 4.1 m high, 5.9 m across the 2 solar-panel wings, and a base diameter of 2 m. Landing capsule: spherical with a diameter of 1.2 m.
Spacecraft Power: Orbiter/bus: 2 solar panels; Lander: batteries (charged by the orbiter/bus prior to separation)
Antenna Diameter: 2.5 m (high-gain antenna)
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi
National Space Science Data Center, http://nssdc.gsfc.nasa.gov/
Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.
Mars 2 was the first of two orbiter-lander-combination spacecraft sent to Mars by the Soviets during the 1971 launch window. The orbiters were roughly cylindrical structures fixed to a large propellant-tank base. The landers were egg-shaped modules with petals that would open on the Martian surface. The 1,000-kilogram landers (of which about 350 kilograms was the actual capsule) were fastened to the top of the bus and protected by a braking shell for entry into the Martian atmosphere. After jettisoning the shell, the landers would deploy parachutes to descend to the Martian surface.
On the Mars 2 trip to the Red Planet, controllers performed two successful midcourse corrections on 17 June and 20 November 1971, respectively. On 27 November 1971, Mars 2 implemented its final midcourse correction, after which the lander probe separated to initiate atmospheric entry. At this point, the onboard computer was designed to implement final corrections to the trajectory, spin the lander around its longitudinal axis, and fire a solid-propellant engine to initiate reentry in a specific direction.
During the flight, after the final midcourse correction, the trajectory of the spacecraft was so accurate that there was no need for further corrective measures. Because of pre-programmed algorithms that assumed a deviated trajectory, the lander was put into an incorrect attitude after separation to compensate for the "error." When the reentry engine fired, the angle of entry proved to be far too steep. The parachute system never deployed, and the lander eventually crashed onto the Martian surface at 4? north latitude and 47? west longitude. It was the first human-made object to make contact with Mars.
Meanwhile, the Mars 2 orbiter successfully entered orbit around Mars at 20:19 UT on 27 November 1971. Parameters were 1,380 x 25,000 kilometers at 48.9? inclination.
The Mars 2 and 3 orbiters 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 2 and 3 had completed their missions by 22 August 1972, after 362 orbits completed by Mars 2 and 20 orbits by Mars 3.
The Mars 2 and 3 probes 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 data enabled creation of surface relief maps, and gave information on the Martian gravity and magnetic fields.