Mission Type: Orbiter
Launch Vehicle: Proton booster plus upper stage and escape stages, 8K82K + Blok D (Proton-K no. 261-01)
Launch Site: Tyuratam (Baikonur Cosmodrome), USSR, NIIP-5 / launch site 81L
Spacecraft Mass: 3,440 kg
Spacecraft Instruments: 1) atmospheric radio-probing instrument; 2) radio telescope; 3) infrared radiometer; 4) spectrophotometer; 5) narrow-band photometer; 6) narrow-band interference-polarization photometer; 7) imaging system; 8) photometers; 9) two polarimeters; 10) ultraviolet photometer; 11) scattered solar radiation photometer; 12) gamma spectrometer; 13) magnetometer; 14) plasma traps and 15) multichannel electrostatic analyzer
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 4 was one of four Soviet spacecraft of the 3M (or M-73) series launched in 1973. Soviet planners were eager to preempt the American Viking missions planned for 1976 but were limited by the less advantageous positions of the planets, which allowed the Proton boosters to launch only limited payloads toward Mars. The Soviets thus separated the standard pair of orbiter-lander payload combinations into two orbiters and two landers.
Less than four months prior to launch, ground testing detected a major problem with the 2T312 transistors used on all four vehicles. An analysis showed that the transistors' failure rate began to increase after 1.5 to 2 years of operation-that is, just about when the spacecraft would reach Mars. Despite the roughly 50-percent odds of success, the government decided to proceed with the missions.
The first spacecraft, Mars 4, successfully left Earth orbit, headed toward Mars and accomplished a single midcourse correction on 30 July 1973, but soon two of three channels of the onboard computer failed due to the faulty transistors. As a result, the second midcourse correction could not be implemented.
With no possibility for Mars orbit insertion, Mars 4 flew by the Red Planet at 15:34 UT on 10 February 1974 at a range of 1,844 kilometers. Ground control was able to command the vehicle to turn on its imaging system at 15:32:41 UT to begin a short photography session of the Martian surface during the flyby. During 6 minutes, cameras performed one regular cycle of imaging that included two panoramas of the surface. The spacecraft eventually entered heliocentric orbit, from which it returned interplanetary data.