Mars 2 Orbiter Spacecraft and Subsystems
The attached orbiter/bus and descent module had a mass of approximately 4650 kg at launch (including fuel) and was 4.1 meters high, 5.9 meters across the two solar panel wings, and had a base diameter of 2 meters. The mass of the orbiter/bus was about 3440 kg fully fueled, and the fueled mass of the descent/lander module was about 1210 kg. The propulsion system was situated at the bottom of the cylindrical spacecraft body and the descent module was mounted on top. The two solar arrays extended from the sides and a 2.5 meter diameter parabolic high-gain communications antenna was also mounted on the side. The instruments and navigation system were located around the bottom of the craft, and the central part of the main body was composed primarily of the fuel tank. Antennae for communications with the lander were affixed to the solar panels. Three low power directional antennae extended from the main body near the parabolic antenna.
For scientific instrumentation (most mounted in a hermetically sealed compartment) the Mars 2 orbital bus carried: a 1 kg infrared radiometer with an 8- to 40-micron range to determine the temperature of the martian surface to -100 degrees C; a photometer to conduct spectral analysis by absorption of atmospheric water vapor concentrations in the 1.38-micron line; an infrared photometer; an ultraviolet photometer to detect atomic hydrogen, oxygen, and argon; a visible range photometer covering six narrow ranges between .37 and .70 microns; an instrument to determine the reflectivity of the surface and atmosphere in the visible (0.3 to 0.6 microns) and the radio-reflectivity of the surface in the 3.4 micron range and the dielectric permeability to give a temperature estimate to a depth of 35 to 50 cm below the surface; carbon dioxide gas absorption strips (2.06 microns) to determine the optical thickness of the atmosphere and hence the surface relief; and two cameras, each with one 4 degree narrow angle lens and one 52 mm focal length wide angle lens, on the same axis and having several light filters, including red, green, blue, and UV. The imaging system returned 1000 x 1000 element scanned pictures by facsimile after development in an automatic onboard laboratory. Radio occultation experiments were also performed when communications transmissions passed through the martian atmosphere in which the refraction of the signals gave information on the atmospheric structure. During the flight to Mars, measurements were made of galactic cosmic rays and solar corpuscular radiation. Eight separate spectrometers were on board to determine the speed, temperature, and composition of the solar wind in the range 30 to 10,000 eV. A three axis magnetometer to measure the interplanetary and martian fields was mounted on a boom extending from one of the solar panels.