发布于 6年前 作者 来自外太空的鱼 1033 次浏览 来自 考研

IN A clean room at the Airbus Defence & Space (ADS) factory north of London, scientists are working on LISAPathfinder (pictured), a hexagon-shaped satellite due to be launched next year. The aim of the ambitious space mission is to try, for the first time, to find and measure gravitational waves—ripples in space-time predicted by Einstein’s general theory of relativity. If that’s possible, earthlings would have further evidence that the theory is true, and they should also, eventually, be able to locate black holes more accurately.

To do all that, however, LISA first has to get to a “Lagrange point”, a place where spacecraft can float stably while getting no farther from the earth. This is essential for detecting the gravitational waves. The only force that could then ruffle LISA would be solar wind, explains Justin Byrne, a deputy director of ADS. Solar wind is so light, however, that developing thrusters soft and accurate enough to counteract it has been “the trickiest bit of all”. It would take 1,000 of the thrusters developed for LISA to lift a single piece of paper; LISA has just four.

This is the kind of technological achievement that has made Britain a leader in satellite design and construction. This week ADS was celebrating the European Space Agency’s Rosetta mission to comet 67P/Churyumov-Gerasimenko. The probe, Philae, that landed on the comet, was assembled largely in Germany. But Rosetta itself was, for the most part, constructed in the same clean room where LISA is being built; Mr Byrne himself was one of the designers of Rosetta when the mission was first conceived about 20 years ago. Altogether ten British companies were involved in the Rosetta mission, making up 20% of the contractors used among 14 European countries. Some of the fancy kit on Philae was British, such as the miniature laboratory built at the Rutherford Appleton laboratory near Oxford to a design from the Open University.

This outsized contribution to the Rosetta mission is now typical of Britain’s place in the firmament of satellite construction. About one-quarter of the world’s commercial communication satellites are built in Britain and 40% of the world’s small satellites. Most of those are built by Airbus’s Surrey Satellite Technology Limited (SSTL), the world leader in the field. It has launched 43 satellites since it was started by an academic at Surrey University, Sir Martin Sweeting. The whole space sector directly employs 35,000 people, and the supply-chain accounts for thousands more jobs. London-based Inmarsat is one of the world’s largest satellite operators, specialising in mobile telephony. The space sector has a turnover of about £11 billion a year.(Economist)



然而,要想完成所有的任务,丽萨首先就必须到达“拉格朗日点”,只有到达了拉格朗日点,宇宙飞船才可以在不远离地球的情况下平稳漂浮。这是探测引力波的必要条件。据ADS的副主任贾斯汀·伯恩(Justin Byrne)解释称,唯一会干扰丽萨的力量就是太阳风。不过太阳风的质量很轻因此只要将推进器设计得足够轻巧和精准就可以与太阳风的力量相抗衡,但这恰恰是“最棘手的问题”。丽萨需要配备1000台这样的推动器才能吹起一张纸;而现在丽萨仅有四台。



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