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TAU (Thousand Astronomical Units) was a proposed unmanned space probe to a distance of one thousand astronomical units (1000 AU) from the Earth and Sun by NASA/JPL in 1987 using tested technology. One scientific purpose would be to measure the distance to other stars via stellar parallax. It was a proposed nuclear electric rocket spacecraft that used a 1 MW fission reactor and an ion drive with a burn time of about 10 years and reach a distance of 1000 AU in 50 years. The primary goal of the mission was to improve parallax measurements of the distances to stars inside and outside the Milky Way, with secondary goals being the study of the heliopause, measurements of conditions in the interstellar medium, and (via communications with Earth) tests of general relativity.〔(【引用サイトリンク】title=Tau - A Mission to a Thousand Astronomical Units )〕 One of the tasks envisioned for TAU would be a flyby of Pluto.〔()〕 A Pluto flyby was achieved in 2015 by the New Frontiers mission ''New Horizons''. Some of the instruments proposed for the design included 1.5-meter telescope for observations and a 1-meter telescope for laser communication with Earth.〔(New Scientist Dec 10, 1987 - And Now for the Stars )〕 After launch it would accelerate to about 100 km/s (about 20 AU/year) over 10 years, using xenon as propellant and a nuclear fission reactor for power.〔(New Scientist Dec 10, 1987 - And Now for the Stars )〕 ==See also== *Innovative Interstellar Explorer (NASA 2003) *Interstellar Probe (NASA 1999) *Interstellar probe (Generic) *Cosmic distance ladder * (has an aphelion over 1000+ AU and orbits the Sun) *Related to Solar System departure: * *Interstellar travel * * (Category) * *Artificial objects escaping the Solar System *Nuclear power in space 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「TAU (spacecraft)」の詳細全文を読む スポンサード リンク
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