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The Mars 2 was an uncrewed space probe of the Mars program, a series of uncrewed Mars landers and orbiters launched by the Soviet Union beginning 19 May 1971. The Mars 2 and Mars 3 missions consisted of identical spacecraft, each with an orbiter and an attached lander. The orbiter is identical to the Venera 9 bus. The type of bus/orbiter is the 4MV. They were launched by a Proton-K heavy launch vehicle with a Blok D upper stage. The lander of Mars 2 became the first human-made object to reach the surface of Mars, although the landing system failed and the lander was lost.

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Mars 2

Mars 3 Orbiter (nearly identical to Mars 2) with lander visible at top
Names	M-71 No. 171
Mission type	Orbiter and lander
Operator	Soviet Union
COSPAR ID	Orbiter: 1971-045A Lander: 1971-045D
SATCAT no.	Orbiter: 5234 Lander: 5739
Mission duration	461 days
Spacecraft properties
Manufacturer	OKB-1
Launch mass	Orbiter: 3,440 kg (7,580 lb) Lander: 1,210 kg (2,670 lb)[1]
Start of mission
Launch date	16:22:44, May 19, 1971 (UTC) (1971-05-19T16:22:44Z)
Rocket	Proton K with Blok D upper stage
End of mission
Disposal	Decommissioned
Deactivated	August 22, 1972 (1972-08-22)
Last contact	last data transmission July 1972[2]
Orbital parameters
Reference system	Areocentric
Mars orbiter
Orbital insertion	27 November 1971
Orbits	362
Orbital parameters
Periareion altitude	1,380 km (860 mi)
Apoareion altitude	24,940 km (15,500 mi)
Inclination	48.9°
Mars lander
Spacecraft component	Mars 2 Lander
Landing date	27 November 1971
Landing site	45°S 47°E

Overview

• Launch Date/Time:
  • Mars 2: 19 May 1971 at 16:22:44 UTC
• Launch mass (including fuel):
  • Combined: 4,650 kg (10,250 lb)
  • Orbiter: 3,440 kg (7,580 lb)
  • Lander: 1,210 kg (2,670 lb)
• On-orbit dry mass: 2,265 kg (4,993 lb)
• Dimensions: 4.1 m (13.5 ft) tall, 2 m (6.6 ft) across (5.9 m (19.4 ft) across with solar panels deployed)

Launch

On 19 May 1971, the Proton-K heavy launch vehicle launched the probe from Baikonur Cosmodrome. After the first stage separated the second stage was ignited. The third stage engine blasted Mars 2 into parking orbit, then the Blok D upper stage sent Mars 2 on the trans-Mars trajectory.

Orbiter

The Orbiter type was the 4MV, used also for Mars-3 and later Mars and Venera Probes. The orbiter engine performed a burn to put the spacecraft into a 1380 x 24,940 km, 18-hour orbit about Mars with an inclination of 48.9 degrees. Scientific instruments were generally turned on for about 30 minutes near periapsis.

The orbiter's primary scientific objectives were to image the Martian surface and clouds, determine the temperature on Mars, study the topography, composition and physical properties of the surface, measure properties of the atmosphere, monitor the solar wind and the interplanetary and Martian magnetic fields, and act as a communications relay to send signals from the landers to the Earth.

By coincidence, a particularly large dust storm on Mars adversely affected the mission. When Mariner 9 arrived and successfully orbited Mars on 14 November 1971, just two weeks prior to Mars 2 and Mars 3, planetary scientists were surprised to find the atmosphere was thick with "a planet-wide robe of dust, the largest storm ever observed." The surface was totally obscured. Unable to reprogram the mission computers, both Mars 2 and Mars 3 dispatched their landers immediately, and the orbiters used up a significant portion of their available data resources in snapping images of the featureless dust clouds below, rather than the surface mapping intended.[3]

The Mars 2 orbiter sent back data covering the period from December 1971 to March 1972, although transmissions continued through August. It was announced that Mars 2 and Mars 3 had completed their missions by 22 August 1972, after 362 orbits. The probe, combined with Mars 3, 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 mbar (0.55 to 0.6 kPa), water vapor concentrations 5,000 times less than in the 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 images and data enabled the creation of surface relief maps,[4] and gave information on Martian gravity and magnetic fields. The orbiter remains in Martian orbit.

Lander

• 
  Map of Mars, showing the location of Mars 2 center left, in relation to Viking 1, Mars Pathfinder and Opportunity
• 
  A cut-away view of the Mars 3 Lander at the NPO Lavochkin Museum
• 
  Mars 2 Lander model at the Memorial Museum of Cosmonautics in Russia

Lander spacecraft system

The Mars 2 descent module was mounted on the bus/orbiter opposite the propulsion system. It consisted of a spherical 1.2 m diameter landing capsule, a 2.9 m diameter conical aerodynamic braking shield, a parachute system and retro-rockets.

The entire descent module had a fueled mass of 1,210 kg, the spherical landing capsule accounting for 358 kg of this. An automatic control system consisting of gas micro-engines and pressurised nitrogen containers provided attitude control. Four "gunpowder" engines were mounted to the outer edge of the cone to control pitch and yaw.

The main and auxiliary parachutes, the engine to initiate the landing, and the radar altimeter were mounted on the top section of the lander. Foam was used to absorb shock within the descent module. The landing capsule had four triangular petals which would open after landing, righting the spacecraft and exposing the instrumentation.

The lander was equipped with two television cameras with a 360 degree view of the surface as well as a mass spectrometer to study atmospheric composition; temperature, pressure, and wind sensors; and devices to measure mechanical and chemical properties of the surface, including a mechanical scoop to search for organic materials and signs of life. It also contained a pennant with the State Emblem of the Soviet Union.

Four aerials protruded from the top of the sphere to provide communications with the orbiter via an onboard radio system. The equipment was powered by batteries which were charged by the orbiter prior to separation. Temperature control was maintained through thermal insulation and a system of radiators. The landing capsule was sterilised before launch to prevent contamination of the Martian environment.

PrOP-M rover

Mars 2 lander had a small 4.5 kg Mars rover on board, which would move across the surface on skis while connected to the lander with a 15-meter umbilical. Two small metal rods were used for autonomous obstacle avoidance, as radio signals from Earth would take too long to drive the rovers using remote control. The rover carried a dynamic penetrometer and a radiation densitometer.[4]

The main PROP-M frame was a squat box with a small protrusion at the center. The frame was supported on two wide flat skis, one extending down from each side elevating the frame slightly above the surface.

The rover was planned to be placed on the surface after landing by a manipulator arm and to move in the field of view of the television cameras and stop to make measurements every 1.5 metres. The traces of movement in the Martian soil would also be recorded to determine material properties.

Because of the demise of the lander, the rover was not deployed.

Entry, descent, and crash landing

The descent module separated from the orbiter on 27 November 1971 about 4.5 hours before reaching Mars. After entering the atmosphere at approximately 6 km/s, the descent system on the module malfunctioned, possibly because the angle of entry was too steep. The descent sequence did not operate as planned and the parachute did not deploy.[4] The descent module became the first man-made object to impact the surface of Mars. The exact crash site is unknown, but it is estimated to be at 45°S 313°W.[3][5] Attempts to contact the probe after the crash were unsuccessful.

See also

• List of Mars orbiters
• List of missions to Mars
• Mars 1M
• Mars program
• Space exploration
• Timeline of artificial satellites and space probes
• Robotic spacecraft

References

External links

• Catalog of Soviet Mars images
• NASA's mars probe website
• Ted Stryk's page on enhancing the partial photo
• TASS notice on the Mars-3 landing (in Russian) (Wikisource)
• "The Rocky Soviet Road to Mars" by Larry Klaes – EJASA October 1989^{[permanent dead link]}

На других языках

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- [en] Mars 2

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[es] Mars 2

La sonda Mars 2 (también llamada o Marte 2) (en ruso: Марс-2) fue una sonda espacial lanzada por la Unión Soviética en 1971 hacia el planeta Marte. Los principales objetivos del orbitador Mars 2 eran los mismos que los de la Mars 3. Era idéntica a la Mars 3, cada una con un módulo orbital y un módulo de descenso acoplado.

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[ru] Марс-2

Марс-2 — советская автоматическая межпланетная станция (АМС) четвёртого поколения космической программы «Марс». Одна из трёх АМС серии М-71. Марс-2 предназначена для исследования Марса как с орбиты, так непосредственно на поверхности Марса. АМС состояла из орбитальной станции — искусственного спутника Марса и спускаемого аппарата с автоматической марсианской станцией. Спускаемый аппарат разбился о поверхность планеты, а станция успешно вышла на орбиту, где проработала свыше 8 месяцев.

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