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The Far Ultraviolet Spectroscopic Explorer (FUSE) is a space-based telescope operated by the Johns Hopkins University Applied Physics Laboratory. ''FUSE'' was launched on a Delta II rocket on June 24, 1999, as a part of NASA's Origins program. ''FUSE'' detected light in the far ultraviolet portion of the electromagnetic spectrum, between 90.5-119.5 nanometres, which is mostly unobservable by other telescopes. Its primary mission was to characterize universal deuterium in an effort to learn about the stellar processing times of deuterium left over from the Big Bang. ''FUSE'' resides in a low Earth orbit, approximately 760 km (410 nmi) in altitude, with an inclination of 25 degrees and just less than a 100-minute orbital period. Its Explorer designation is Explorer 77. On July 12, 2007, ''FUSEs final reaction wheel, which is required for accurately pointing a spacecraft, failed and efforts to restart it were unsuccessful. An announcement was made on September 6 that because the fine control needed to perform its mission had been lost, the ''FUSE'' mission would be terminated.〔 == Optical design == Although the original specification was to have a Wolter-type grazing incidence telescope, the final design of the ''FUSE'' telescope comprises four individual mirrors. Each of the four mirrors is a 39-by-35 cm (15.4-by-13.8 in) off-axis parabola. Two mirror segments are coated with silicon carbide for reflectivity at the shortest ultraviolet wavelengths, and two mirror segments are coated with lithium fluoride over aluminum that reflects better at longer wavelengths. This optimizes performance over the entire spectral range.〔 Each mirror has a corresponding astigmatism-corrected, holographically-ruled diffraction grating, each one on a curved substrate so as to produce four 1.65 m (5.4 ft) Rowland circle spectrographs. The dispersed ultraviolet light is detected by two microchannel plate intensified double delay-line detectors, whose surfaces are curved to match the curvature of the focal plane. 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「Far Ultraviolet Spectroscopic Explorer」の詳細全文を読む スポンサード リンク
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