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Journey to Enceladus and Titan (JET) is an astrobiology mission concept to assess the habitability potential of Enceladus and Titan, moons of Saturn. The JET orbiter concept was proposed in 2011 by the Jet Propulsion Laboratory to NASA's Discovery Program for its 13th mission. In September 2016 NASA will announce the winner of the competition and fund its development for a launch by the end of 2021. ==Concept== Enceladus is a small icy moon, seemingly similar in chemical makeup to comets, with jets or geysers of water erupting from its surface that might be connected to active hydrothermal vents at its subsurface water ocean floor,〔(Ocean Within Enceladus May Harbor Hydrothermal Activity ). March 11, 2015.〕 where the moon's ocean meets the underlying rock, a prime habitat for life. The geysers could provide easy access for sampling the moon's subsurface ocean, and if there is microbial life in it, ice particles from the sea could contain the evidence astrobiologists need to identify them. An organic-rich world, Titan has a methane cycle comparable in atmospheric and geological processes to Earth's water cycle. The JET orbiter mission concept was proposed in 2011 by the Jet Propulsion Laboratory to NASA's Discovery Program Mission #13. During the orbiter's one-year mission, it would perform high-resolution mass spectroscopy mapping that would determine what processes have shaped and are shaping the moons, and it would permit assessment of the habitability potential of Enceladus and Titan.〔〔 In order to meet the $450 million cost cap, the orbiter would carry only two instruments. It would orbit Saturn and make a total of 16 flybys of Enceladus and Titan, the closest ones at 900 km from Titan's surface.〔 In June 2015 NASA will announce a list of finalists for the current competition, followed by NASA's announcement of the winner in September 2016. The selected mission must launch by the end of 2021. 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「Journey to Enceladus and Titan」の詳細全文を読む スポンサード リンク
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