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BeppoSAX was an Italian–Dutch satellite for X-ray astronomy which played a crucial role in resolving the origin of gamma-ray bursts (GRBs), the most energetic events known in the universe. It was the first X-ray mission capable of simultaneously observing targets over more than 3 decades of energy, from 0.1 to 300 kiloelectronvolts (keV) with relatively large area, good (for the time) energy resolution and imaging capabilities (with a spatial resolution of 1 arc minute between 0.1 and 10 keV). BeppoSAX was a major programme of the Italian Space Agency (ASI) with the participation of the Netherlands Agency for Aerospace Programmes (NIVR). The prime contractor for the space segment was Alenia while Nuova Telespazio led the development of the ground segment. Most of the scientific instruments were developed by the Italian National Research Council (CNR) while the Wide Field Cameras were developed by the Netherlands Institute for Space Research (SRON) and the LECS was developed by the astrophysics division of the European Space Agency's ESTEC facility. BeppoSAX was named in honour of the Italian physicist Giuseppe "Beppo" Occhialini. SAX stands for "Satellite per Astronomia a raggi X" or "Satellite for X-ray Astronomy". X-ray observations cannot be performed from ground-based telescopes, since Earth's atmosphere blocks most of the incoming radiation. One of BeppoSAX's main achievements was the identification of numerous gamma ray bursts with extra-galactic objects. (See the linked article for details.) Launched by an Atlas-Centaur on 30 April 1996 into a low inclination (<4 degree) low-Earth orbit, the expected operating life of two years was extended to April 30, 2002 due to high scientific interest in the mission and the continued good technical status. After this date, the orbit started to decay rapidly and various subsystems were starting to fail making it no longer worthwhile to conduct scientific observations. On April 29, 2003, the satellite ended its life falling into the Pacific Ocean. == Spacecraft characteristics == BeppoSAX was a three axes stabilized satellite, with a pointing accuracy of 1'. The main attitude constraint derived from the need to maintain the normal to the solar arrays within 30° from the Sun, with occasional excursions to 45° for some WFC observations. Due to the low orbit the satellite was in view of the ground station of Malindi for only a limited fraction of the time. Data was stored on-board on a tape unit with a capacity of 450 Mbits and transmitted to ground every orbit during station passage. The average data rate available to instruments was about 60 kbit/s, but peak rates of up to 100 kbit/s can be retained for part of each orbit. With the solar panels closed, the spacecraft was 3.6 m in height and 2.7 m in diameter. The total mass amounts to 1400 kg, with a payload of 480 kg. The structure of the satellite consisted of three basic functional subassemblies: * the Service Module, in the lower part of the spacecraft, which housed all the subsystems and the electronic boxes of the scientific instruments. * the Payload Module, which housed the scientific instruments and the star trackers. * the Thermal Shade Structure, that enclosed the Payload Module. The primary sub-systems of the satellite are: * The Attitude Orbital Control System (AOCS), that performed attitude determination and manoeuvred and operated the Reaction Control Subsystem in charge of orbit recovering. It included redundant magnetomers, Sun acquisition sensors, three star trackers, six gyroscopes (three of which are for redundancy), three magnetic torquers and four reaction wheels, all controlled by a dedicated computer. The AOCS ensured a pointing accuracy of 1' during source observations and manoeuvres with a slew rate of 10° per min. * The On Board Data Handler (OBDH) was the core for data management and system control on the satellite and it also managed the communication interfaces between the satellite and the ground station. Its computer supervised all subsystem processor activities, such as those of each instrument, and the communication busses. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「BeppoSAX」の詳細全文を読む スポンサード リンク
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