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  3. Aristotle believed that the heavens were perfect. If they ever were, they are no longer. The skies above Earth are now littered

Aristotle believed that the heavens were perfect. If they ever were, they are no longer. The skies above Earth are now littered

admin2011-03-11  92
问题     Aristotle believed that the heavens were perfect. If they ever were, they are no longer. The skies above Earth are now littered with the debris (残骸) of dead satellites, bits of old rockets and the odd tool dropped by a spacewalking astronaut. Such is the extent of the detritus that the first accidental collision between two satellites has already taken place. It happened in February 2009, when a defunct (废弃的) Russian Cosmos smashed into a functioning American Iridium, destroying both and creating even more space junk.
    To stop this sort of thing happening again Vaios Lappas of the University of Surrey, in England, has designed a system that will remove satellites from orbit at the end of their useful lives--and as a bonus will scour part of the sky clean as it does so. Dr. Lappas’s satellite-removal system employs a solar sail. As light from the sun hits the sail, it imparts a minuscule but continuous acceleration. When a satellite is first launched, the sail is angled in a way that causes this acceleration to keep the satellite in orbit. (Orbits gradually decay as a result of collisions with the small number of air molecules found even at altitudes normally classified as "outer space". )
    Solar sails have yet to be used widely to propel spacecraft in this way--several earlier versions came unstuck when the sails failed to unfurl properly-but doing so is not a novel idea in principle The novelty Dr. Lappas envisages is to change the angle of the sail when the satellite has become defunct. Instead of keeping the derelict craft in orbit, it will, over the course of a couple of years, drag it into the atmosphere and thus to a fiery end. Not only that, but the sail will also act like a handkerchief, mopping up microscopic orbital detritus such as flecks of paint from previous launches. A fleck of paint may not sound dangerous, but if travelling at 27 000kph (17 000mph), as it would be in orbit, it could easily penetrate an astronaut’s spacesuit.
    A prototype of Dr. Lappas’s design, called CubeSail, will be launched late next year. It weighs just 3kg and, when folded up, measures 30cm (12 inches) by 10era by 10era. Once unfurled, however, the sail will have an area of 25 square metres. If this prototype, which is paid for by EADS, a European aerospace company, proves successful, solar sails might be added to many future satellites. That would enable them to be removed rapidly from orbit when they became useless and would restore to the skies some measure of Aristotelian perfection.
Which one is NOT the application of the system designed by Vaios Lappas?
选项 A、To halt creating more space junk.
B、To remove the satellites at the end of their useful lives.
C、To stop the accidental collisions in space.
D、To clean the junk created by dead satellites.
答案C
解析 文章第二段讲述拉帕斯设计的系统的应用情况。第一句中that引导的定语从句对system进行了解释说明，即能在卫星完成使命后将其从轨道中清除，[B]是对该意思的同义转述。第一句破折号后提到这个系统还有一个附带作用，就是能够清洁天空，也就是清扫太空垃圾的作用，[A]和[D]谈到的就是此作用。通过排除法可知，[C]不是这个系统的作用，也不是拉帕斯发明此系统的用意，故为正确答案。  
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