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Mariner 1-2
Part of Mariner
Mariner 1, 2
Mariner 1, 2
Credit: NASA
American Venus probe. The world's first successful interplanetary spacecraft.

Status: Operational 1962. First Launch: 1962-07-22. Last Launch: 1962-08-27. Number: 2 . Gross mass: 200 kg (440 lb).

The objective of the mission was to fly by Venus and return data on the planet's atmosphere, magnetic field, charged particle environment, and mass. It also made measurements of the interplanetary medium during its cruise to Venus and after the flyby.

Mariner was based on the Ranger lunar spacecraft. Mariner 2 consisted of a hexagonal base, 1.04 meters across and 0.36 meters thick, which contained six magnesium chassis housing the electronics for the science experiments, communications, data encoding, computing, timing, and attitude control, and the power control, battery, and battery charger, as well as the attitude control gas bottles and the rocket engine. On top of the base was a tall pyramid-shaped mast on which the science experiments were mounted which brought the total height of the spacecraft to 3.66 meters. Attached to either side of the base were rectangular solar panel panels with a total span of 5.05 meters and width of 0.76 meters. Attached by an arm to one side of the base and extending below the spacecraft was a large directional dish antenna.

The Mariner 2 power system consisted of the two solar cell panels, one 183 cm by 76 cm and the other 152 cm by 76 cm. A 31 cm Dacron extension (a solar sail) was used to balance the solar pressure on the panels. These powered the craft directly or recharged a 1000 Watt-hour sealed silver-zinc cell battery, which was used before the panels were deployed, when the panels were not illuminated by the sun, and when loads were heavy. A power-switching and booster regulator device controlled the power flow.

Communications consisted of a 3 Watt transmitter capable of continuous telemetry operation, the large high gain directional dish antenna, a cylindrical omnidirectional antenna at the top of the instrument mast, and two command antennas, one on the end of either solar panel, which received instructions for midcourse maneuvers and other functions.

Propulsion for midcourse maneuvers was supplied by a monopropellant (anhydrous hydrazine) 225 N retro-rocket. The hydrazine was ignited using nitrogen tetroxide and aluminum oxide pellets, and thrust direction was controlled by four jet vanes situated below the thrust chamber. Attitude control with a 1 degree pointing error was maintained by a system of nitrogen gas jets. The Sun and Earth were used as references for attitude stabilization. Overall timing and control was performed by a digital Central Computer and Sequencer. Thermal control was achieved through the use of passive reflecting and absorbing surfaces, thermal shields, and movable louvers.

The scientific experiments were mounted on the instrument mast and base. A magnetometer was attached to the top of the mast below the omnidirectional antenna. Particle detectors were mounted halfway up the mast, along with the cosmic ray detector. A cosmic dust detector and solar plasma spectrometer detector were attached to the top edges of the spacecraft base. A microwave radiometer and an infrared radiometer and the radiometer reference horns were rigidly mounted to a 48 cm diameter parabolic radiometer antenna mounted near the bottom of the mast. All instruments were operated throughout the cruise and encounter modes except the radiometers, which were only used in the immediate vicinity of Venus.

Scientific discoveries made by Mariner 2 included a slow retrograde rotation rate for Venus, hot surface temperatures and high surface pressures, a predominantly carbon dioxide atmosphere, continuous cloud cover with a top altitude of about 60 km, and no detectable magnetic field. It was also shown that in interplanetary space the solar wind streamed continuously and the cosmic dust density was much lower than the near-Earth region. Improved estimates of Venus' mass and the value of the astronomical unit were made.

More at: Mariner-1.

Family: Venus. Country: USA. Launch Vehicles: Atlas, Atlas Centaur LV-3C, Atlas Agena B. Projects: Mariner. Launch Sites: Cape Canaveral, Cape Canaveral LC12. Agency: JPL, NASA. Bibliography: 126, 18, 2, 278, 296, 3875, 3883, 3894, 3897, 6, 12793.
Photo Gallery

Mariner 1Mariner 1
Credit: Manufacturer Image

1961 September 28 - . LV Family: Atlas. Launch Vehicle: Atlas Centaur LV-3C.
1962 July 22 - . 09:21 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC12. LV Family: Atlas. Launch Vehicle: Atlas Agena B. FAILURE: Destroyed by range safety.. Failed Stage: U.
1962 August 27 - . 06:53 GMT - . Launch Site: Cape Canaveral. Launch Complex: Cape Canaveral LC12. LV Family: Atlas. Launch Vehicle: Atlas Agena B.
1962 December 14 - .

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