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离子推进卫星提高地球与火星间通信能力
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[据每日科学网站近日报道] 地球和火星之间的直接通信会被太阳强烈干扰甚至封锁，每次持续数周，中断人类未来造访火星的任务。来自欧空局和英国的工程师们可能已经找到了解决方案——采用新型轨道与连续离子动力推进相结合的方式。
欧洲研究人员研究了影响未来人类火星任务可能出现的关键问题的解决方案：如何确保无线电通信的稳定性，即使在火星和地球直线位于太阳两侧，所有的地面对火星任务控制信号都被封锁的情况下。这种情况被称为“交合”（conjunction），每780天出现一次。
火星通信问题的解决方案是在火星附近特定的轨道（B-orbit）上放置两颗通信中继卫星。然而，为使卫星不受重力影响保持在原位，他们将安装先进的电离子推进器。
离子推进由太阳光提供动力，以微量的氙气作为推进剂，将使卫星停留在地球和火星的轨道之间。卫星就能够在“交合”期间中继火星与地球之间的无线电信号，确保在火星的宇航员和地球的联系。 （中国航天工程咨询中心 侯丹 陈菲）
New Concept May Enhance Earth-Mars Communication
http://www.sciencedaily.com/releases/2009/10/091016094030.htm
ScienceDaily (Oct. 16, 2009) — Direct communication between Earth and Mars can be strongly disturbed and even blocked by the Sun for weeks at a time, cutting off any future human mission to the Red Planet. An ESA engineer working with engineers in the UK may have found a solution using a new type of orbit combined with continuous-thrust ion propulsion.
The European researchers studied a possible solution to a crucial problem affecting future human missions to Mars: how to ensure reliable radio communication even when Mars and Earth line up at opposite sides of the Sun, which then blocks any signal between mission controllers on Earth and astronauts on the red surface. The natural alignment, known as a conjunction, happens approximately every 780 days, and would seriously degrade and even block transmission of voice, data and video signals.
The research findings were released this week at the 60th International Astronautical Congress (IAC), the world's biggest space event, being held in Daejeon, South Korea. This new solution is one result of a €100 000 study funded by ESA's General Studies Programme to catalogue non-traditional orbital zones throughout the Solar System that could be exploited thanks to emerging propulsion technologies.
According to the paper, "Non-Keplerian Orbits Using Low Thrust, High ISP Propulsion Systems," an innovative solution to the Mars communication problem may be found by placing a pair of communication relay satellites into a very special type of orbit near Mars: a so-called 'B-orbit' (in contrast to an 'A-orbit', based on natural orbital laws).
However, to counter the effects of gravity and remain in place, they would have to be equipped with cutting-edge electric ion propulsion.
The ion thrusters, powered by solar electricity and using tiny amounts of xenon gas as propellant, would hold the satellites in a B-orbit in full view of both Mars and Earth. The satellites could then relay radio signals throughout the Mars–Earth conjunction season, ensuring that astronauts at Mars were never out of touch with Earth.
https://blog.sciencenet.cn/blog-80228-264315.html
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