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- The Mariner 2 spacecraft was the second of a series of spacecraft used for planetary exploration in the flyby, or nonlanding, 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 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 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. Group: Platform_Details Entry_ID: MARINER 2 Group: Platform_Identification Platform_Category: Interplanetary Spacecraft Platform_Series_or_Entity: FLYBY Short_Name: MARINER 2 End_Group Group: Synonymous_Platform_Names Short_Name: Mariner-Venus 1962 Short_Name: 00374 End_Group Group: Platform_Associated_Instruments Short_Name: MAGNETOMETERS End_Group Creation_Date: 2007-08-13 Online_Resource: http://www.jpl.nasa.gov/missions/past/mariner1-2.html Sample_Image: http://nssdc.gsfc.nasa.gov/image/spacecraft/mariner02.gif Group: Platform_Logistics Launch_Date: 1962-08-27 Primary_Sponsor: NASA End_Group End_Group
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| Abstract from DBPedia | Mariner 2 (Mariner-Venus 1962), an American space probe to Venus, was the first robotic space probe to conduct a successful planetary encounter. The first successful spacecraft in the NASA Mariner program, it was a simplified version of the Block I spacecraft of the Ranger program and an exact copy of Mariner 1. The missions of the Mariner 1 and 2 spacecraft are sometimes known as the Mariner R missions. Original plans called for the probes to be launched on the Atlas-Centaur, but serious developmental problems with that vehicle forced a switch to the much smaller Agena B second stage. As such, the design of the Mariner R vehicles was greatly simplified. Far less instrumentation was carried than on the Soviet Venera probes of this period—for example, forgoing a TV camera—as the Atlas-Agena B had only half as much lift capacity as the Soviet 8K78 booster. The Mariner 2 spacecraft was launched from Cape Canaveral on August 27, 1962, and passed as close as 34,773 kilometers (21,607 mi) to Venus on December 14, 1962. The Mariner probe consisted of a 100 cm (39.4 in) diameter hexagonal bus, to which solar panels, instrument booms, and antennas were attached. The scientific instruments on board the Mariner spacecraft were: two radiometers (one each for the microwave and infrared portions of the spectrum), 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 and to make basic measurements of Venus' atmosphere. The primary mission was to receive communications from the spacecraft in the vicinity of Venus and to perform radiometric temperature measurements of the planet. A second objective was to measure the interplanetary magnetic field and charged particle environment. En route to Venus, Mariner 2 measured the solar wind, a constant stream of charged particles flowing outwards from the Sun, confirming the measurements by Luna 1 in 1959. It also measured interplanetary dust, which turned out to be scarcer 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.マリナー2号（マリナー2ごう、Mariner 2）はアメリカ航空宇宙局 (NASA) のマリナー計画の金星探査機である。マリナー1号の予備機として用意されていたが、マリナー1号の失敗によりレインジャー計画に金星用の改良を加え36日後に打ち上げられることになり、アメリカ初の成功した惑星探査機となった。3か月半の飛行を経て金星上空を通過しミッションを完了、世界初のフライバイ（惑星への接近飛行）に成功した。1962年8月27日打ち上げ、12月14日に金星から35,000kmの地点を通過しユージン・ニューマン・パーカーによって4年前に予言されていた太陽風と、金星表面の温度が高温であることを観測した。 (Source: http://dbpedia.org/resource/Mariner_2) |
