Mars 4 Orbiter

Launch data: Designation 06742 / 73047A Launch date 21 Jul 1973 - 19:30:59 UT Launch site B, LC-81/23 Launch vehicle Proton-K/D (261-01 8K82K/11S824) Satellite type  3MS N° 52S Mission Mars probe Heliocentric orbit Perihelion / Aphelion  1.02 x 1.63 AU Eccentricity  0.23 Inclination  2.2 deg Period  555 days

Specifications:

Description:

• Mars spacecraft series built for 1973 missions. Due to unfavorable position of Mars during that campaign, separate versions built: two intended to orbit Mars and map the surface, and two to land capsules. The orbiters were equipped with instrumentation to study the composition, structure, and properties of the Martian atmosphere and surface, including an imaging device, a 256 channel gamma-ray spectrometer mounted on a boom and a Lyman-Alpha photometer. The landers would have separated from their uninstrumented bus, entered the atmosphere, where a parachute opened, slowing the descent. The lander equipment included a Lyman-Alpha photometer and a Bennett mass analyzer. Unfortunately, this entire series of spacecraft experienced failures on arrival at Mars due to pre-flight test of the electronics with helium, which resulted in degradation of the computer chips during the journey to Mars. Orbiters had a launch mass of 3444 kg, and landers 3260 kg.

Mission details:

• Passed 2200 km behind Mars on 1974 Feb 10.
• Failed; did not enter Martian orbit as planned; intended to be a Mars orbiter mission. Mars 4 reached Mars on 10 February 1974. Due to use of helium in preflight tests of the computer chips, which resulted in degradation of the chips during the voyage to Mars, the retro-rockets never fired to slow the craft into Mars orbit. Mars 4 flew by the planet at a range of 2,200 km. It returned one swath of pictures and some radio occultation data. Final heliocentric orbit 1.02 x 1.63 AU, 2.2 degree inclination, 556 day period.