Mariner 2

Mariner 2

Organization:JPL - NASA
Mission type:Fly-by
[ edit]


Mariner 2 (Mariner-Venus 1962), a space probe to Venus, was the first successful spacecraft in the NASA Mariner program. The Mariner 1 and 2 spacecraft were simplified versions of the Block I spacecraft of the Ranger program.

The Mariner probe consisted of a 100 cm diameter hexagonal bus, to which solar panels, instrument booms, and antennas were attached. The scientific instruments onboard the Mariner spacecraft were two radiometers (microwave and infrared) mounted on a tilting platform, a micrometeorite sensor, a solar plasma sensor, a charged particle sensor, and a magnetometer. These instruments were designed to measure the temperature distribution on the surface of Venus, as well as making basic measurements of Venus' atmosphere. Due to the planet's thick, featureless cloud cover, no cameras were included in the Mariner units. (Mariner 10, a distant cousin of Mariner 2, later discovered that extensive cloud detail was visible in ultra-violet light.)

Its goal was to measure the planet's atmosphere, magnetic field, charged particle environment, and mass.

The Atlas-Agena rocket carrying Mariner 1 veered off-course during its launch on July 22, 1962, and the spacecraft was destroyed. A month later, the identical Mariner 2 spacecraft was launched successfully on August 27, 1962, sending it on a 3½-month flight to Venus. On the way it measured the solar wind, a constant stream of charged particles flowing outwards from the Sun, confirming its measurement by Luna 1 in 1959. It also measured interplanetary dust, which turned out to be more scarce than predicted. In addition, Mariner 2 detected high-energy charged particles coming from the Sun, including several brief solar flares, as well as cosmic rays from outside the Solar system. As it flew by Venus on December 14, 1962, Mariner 2 scanned the planet with its pair of radiometers, revealing that Venus has cool clouds and an extremely hot surface.

The spacecraft is now defunct in a heliocentric orbit.

Detailed description

The Mariner 2 spacecraft was the second of a series of spacecraft used for planetary exploration in the flyby mode and the first spacecraft to successfully encounter another planet. Mariner 2 was a backup for the Mariner 1 mission which failed shortly after launch to Venus. The objective of the Mariner 2 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.

Spacecraft and subsystems

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 altitude control, and the power control, battery, and battery charger, as well as the altitude 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 wings 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 wings, one 183 cm by 76 cm and the other 152 cm by 76 cm (with a 31 cm dacron extension (a solar sail) to balance the solar pressure on the panels) which 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.

Instruments:
  1. Microwave Radiometer
  2. Infrared Radiometer
  3. Three-axis Fluxgate Magnetometer
  4. Cosmic Dust Detector
  5. Solar Plasma Spectrometer
  6. Particle Detector
  7. Cosmic Ray Detector
  8. Celestial Mechanics

Mission profile

Mariner 2 was launched from Cape Canaveral Air Force Station Launch Complex 12. After launch and termination of the Agena first burn, the Agena-Mariner was in a 118 km altitude Earth parking orbit. The Agena second burn some 980 seconds later followed by Agena-Mariner separation injected the Mariner 2 spacecraft into a geocentric escape hyperbola at 26 minutes 3 seconds after lift-off. Solar panel extension was completed about 44 minutes after launch. On 29 August 1962 cruise science experiments were turned on. The midcourse maneuver was initiated at 22:49:00 UT on 4 September and completed at 2:45:25 UT 5 September. On 8 September at 17:50 UT the spacecraft suddenly lost its altitude control, which was restored by the gyroscopes 3 minutes later. The cause was unknown but may have been a collision with a small object. On October 31 the output from one solar panel deteriorated abruptly, and the science cruise instruments were turned off. A week later the panel resumed normal function and instruments were turned back on. The panel permanently failed on 15 November, but Mariner 2 was close enough to the Sun that one panel could supply adequate power. On December 14 the radiometers were turned on. Mariner 2 approached Venus from 30 degrees above the dark side of the planet, and passed below the planet at its closest distance of 34,773 km at 19:59:28 UT 14 December 1962. After encounter, cruise mode resumed. Spacecraft perihelion occurred on 27 December at a distance of 105,464,560 km. The last transmission from Mariner 2 was received on 3 January 1963 at 07:00 UT. Mariner 2 remains in heliocentric orbit.

Scientific results

Scientific discoveries made by Mariner 2 included the detection of microwave limb darkening, which supported the theory that the Venusian surface was extremely hot, and it found no detectable magnetic field. It was also shown that in interplanetary space the solar wind streams continuously and the cosmic dust density is much lower than the near-Earth region. Improved estimates of Venus' mass and the value of the astronomical unit were made.

Total research, development, launch, and support costs for the Mariner series of spacecraft (Mariners 1 through 10) was approximately $554 million.

External links

     [ e] 
Mariner Program
Previous mission: Mariner 1Next mission: Mariner 3
Mariner 1 | Mariner 2 | Mariner 3 | Mariner 4 | Mariner 5 | Mariner 6 and 7 | Mariner 8 | Mariner 9 | Mariner 10


VENUS is an acronym for the Victoria Experimental Network Under the Sea . The VENUS project is operated out of the University of Victoria and is an advanced cabled sea floor observatory, consisting of fibre optic cables connecting oceanographic instruments on the sea floor of the
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spacecraft is a vehicle or device designed for spaceflight. On a sub-orbital spaceflight, a spacecraft enters outer space but then returns to the planetary surface (such as Earth) without making a complete orbit.
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The Mariner program was a program conducted by the American space agency NASA that launched a series of robotic interplanetary probes designed to investigate Mars, Venus and Mercury.
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Mariner 1 was the first spacecraft of the Mariner program. Intended to fly by Venus, it failed during launch on July 22, 1962. A hardware failure in an antenna caused the booster to lose contact with guidance systems on the ground, so an onboard computer assumed control.
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The Ranger program was a series of unmanned space missions by the United States in the 1960s whose objective was to obtain the first close-up images of the surface of the Moon.
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Microwaves are electromagnetic waves with wavelengths shorter than one meter and longer than one millimeter, or frequencies between 300 megahertz and 300 gigahertz.
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Infrared (IR) radiation is electromagnetic radiation of a wavelength longer than that of visible light, but shorter than that of radio waves. The name means "below red" (from the Latin infra, "below"), red being the color of visible light with the longest wavelength.
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A Micrometeoroid (also micrometeorite, micrometeor) is a tiny meteoroid; a small particle of rock in space, usually weighing less than a gram.

Scientific interest

See also: Cosmic dust

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In physics, a charged particle is a particle with an electric charge. It may be either a subatomic particle or an ion. A collection of charged particles, or even a gas containing a proportion of charged particles, is called a plasma, which is called the
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A magnetometer is a scientific instrument used to measure the strength and/or direction of the magnetic field in the vicinity of the instrument.

Earth's magnetism varies from place to place and differences in the Earth's magnetic field (the magnetosphere) can be caused by
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camera is a device used to capture images, as still photographs or as sequences of moving images (movies or videos). The term as well as the modern-day camera evolved from the camera obscura
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Mariner 10 was a robotic space probe launched on November 3, 1973 to fly by the planets Mercury and Venus. It was launched approximately 2 years after Mariner 9 and was the last spacecraft in the Mariner program (Mariner 11 and 12 were redesignated Voyager 1 and Voyager 2).
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solar wind is a stream of charged particles (i.e., a plasma) which are ejected from the upper atmosphere of the sun. It consists mostly of high-energy electrons and protons (about 1 keV) that are able to escape the sun's gravity in part because of the high temperature of the corona
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Luna 1 (E-1 series) was the first of a number of spacecraft to reach the vicinity of the Moon and the first of the Luna programme of Soviet automatic interplanetary stations successfully launched in the direction of the Moon.
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Cosmic dust is a type of dust composed of particles in space which are a few molecules to 0.1 mm in size. Cosmic dust can be further distinguished by its astronomical location; for example: intergalactic dust, interstellar dust, circumplanetary dust, dust clouds around other stars,
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solar flare is a violent explosion in the Sun's atmosphere releasing up to a total energy of 6.298 × 1025 Joules.[1] Solar flares take place in the solar corona and chromosphere, heating plasma to tens of millions of kelvins and accelerating electrons,
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Cosmic rays are energetic particles originating from space that impinge on Earth's atmosphere. Almost 90% of all the incoming cosmic ray particles are protons, about 9% are helium nuclei (alpha particles) and about 1% are electrons.
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Solar System or solar system[a] consists of the Sun and the other celestial objects gravitationally bound to it: the eight planets, their 166 known moons,[1]
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A heliocentric orbit is an orbit around the Sun. In our Solar System, all planets, comets, and asteroids are in such orbits, as are many artificial probes and pieces of debris. The Moon, by contrast, is not in a heliocentric orbit as it orbits the Earth.
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