Mars 5 (), also known as 3MS No.53S was a Soviet spacecraft launched to explore Mars. A 3MS spacecraft launched as part of the

Mars program The Mars program was a series of uncrewed spacecraft launched by the Soviet Union between 1960 and 1973. The spacecraft were intended to explore Mars, and included flyby probes, landers and orbiters. Early Mars spacecraft were small, and launche ...

me, it successfully entered orbit around Mars in 1974. However, it failed a few weeks later.

Spacecraft

The Mars 5 spacecraft carried an array of instruments to study Mars. In addition to cameras, it was equipped with a radio telescope, an IR radiometer, multiple photometers, polarimeters, a magnetometer, plasma traps, an electrostatic analyser, a

gamma-ray spectrometer A gamma-ray spectrometer (GRS) is an instrument for measuring the distribution (or spectrum—see figure) of the intensity of gamma radiation versus the energy of each photon. The study and analysis of gamma-ray spectra for scientific and techni ...

, and a radio probe. The Three cameras were a 52mm Vega, a 350mm Zulfar and a panoramic camera. Built by Lavochkin, Mars 5 was the second of two 3MS spacecraft launched to Mars in 1973, following

Mars 4 Mars 4 (), also known as 3MS No.52S was a Soviet spacecraft intended to explore Mars. A 3MS spacecraft launched as part of the Mars programme, it was intended to enter orbit around Mars in 1974. However, computer problems prevented orbital inser ...

. A 3MS was also launched during the 1971 launch window as Kosmos 419. However, due to a launch failure, it failed to depart Earth orbit. In addition to the orbiters, two 3MP lander missions,

Mars 6 Mars 6 (), also known as 3MP No.50P was a Soviet spacecraft launched to explore Mars. A 3MP bus spacecraft launched as part of the Mars program, it consisted of a lander, and a coast stage with instruments to study Mars as it flew past. Spacec ...

and

Mars 7 Mars 7 (), also known as 3MP No.51P was a Soviet spacecraft launched in 1973 to explore Mars. A 3MP bus spacecraft which comprised the final mission of the Mars programme, it consisted of a lander and a coast stage with instruments to study Mars ...

, were launched during the 1973 window.

Launch

Mars 5 was launched by a Proton-K carrier rocket with a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/24. The launch occurred at 18:55:48 UTC on 25 July 1973, with the first three stages placing the spacecraft and upper stage into a low Earth

parking orbit A parking orbit is a temporary orbit used during the launch of a spacecraft. A launch vehicle boosts into the parking orbit, then coasts for a while, then fires again to enter the final desired trajectory. The alternative to a parking orbit is ''di ...

before the Blok D fired to propel Mars 5 into heliocentric orbit bound for Mars. The spacecraft performed course correction manoeuvres on 3 August 1973 and 2 February 1974.

Mars orbit

The probe reached Mars on 12 February 1974. At 14:44:25 the spacecraft's engines ignited to begin its orbit insertion burn, which successfully placed it into an Areocentric orbit with a

periapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

of , an

apoapsis An apsis (; ) is the farthest or nearest point in the orbit of a planetary body about its primary body. For example, the apsides of the Earth are called the aphelion and perihelion. General description There are two apsides in any elli ...

of , and 35.3 degrees

inclination Orbital inclination measures the tilt of an object's orbit around a celestial body. It is expressed as the angle between a reference plane and the orbital plane or axis of direction of the orbiting object. For a satellite orbiting the Eart ...

. The spacecraft's pressurised instrument compartment began to leak as soon as the spacecraft entered orbit around Mars, which controllers believed to be the result of a micrometeoroid impact during orbital insertion. It ceased operations on 28 February, having returned 180 photographic frames, 43 of which were of usable quality. The probe's original planned lifetime in Mars orbit had been three months. The probe's gamma ray spectrometer measured the uranium, thorium and potassium content of the surface the probe passed over and found they were similar to

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

s on Earth. The exact ratios of the elements varied with the age of the surface. Mars 5's Infrared radiometer reported a daytime surface temperature of between . Night time temperatures were measured at . The probe also made a number of observations of Mars's atmosphere. It found an ozone layer at an altitude of and observed clouds.

References

{{Use dmy dates, date=January 2014 1973 in spaceflight 1973 in the Soviet Union Derelict satellites orbiting Mars Mars program Spacecraft launched in 1973 4MV Non Earth orbiting satellites of the Soviet Union

Spacecraft

Launch

Mars orbit

See also

References