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重要詞組：
阿波羅計劃：Apollo project
鼎盛時期：zenith
航天器上的倉：module
航天飛機：space shuttle
火星：Mars
國際空間站：International Space Station
利用納米技術的放熱擋板：nanotech-based heat shielding
NASA：美國航空航天局，太空總署

補充閱讀資料（節選自economist）

NASA has never really recovered its direction since the triumph of the Apollo project. The zenith of that project was 40 years ago today on July 20th 1969, when Neil Armstrong stepped out of Apollo 11’s lunar module onto the Sea of Tranquillity, and promptly fluffed his lines. The cancellation of Apollo three years later started the slide, and the space shuttles that were supposed to fill the gap failed to become the workaday vehicles that had been promised. The agency’s probes have visited all of the solar system’s planets and it has done a lot of important science. But its manned space programme has never got back the pizzazz of 1969.

Five years ago George Bush outlined a plan to return Americans to the moon in 2020, with an option on going to Mars later. Now that plan is the subject of a rather un-American bout of introspection and self-examination. At the behest of Barack Obama’s newly empowered Office of Science and Technology Policy (OSTP), NASA, America’s space agency, is submitting to an independent review of its human-spaceflight plans in order to determine their future.

This year has been a particularly difficult one for NASA. It started with the incoming administration asking some hard questions, such as how much money could be saved by cancelling various bits of the spacecraft that the agency plans to use to replace its fleet of ageing shuttles—which, among other things, provide America’s only direct link with the International Space Station. The shuttles are due to retire next year, and there is already consternation about the gap between that retirement and the arrival of their successor.

The starting point for the review is a simple one: money. Mr Obama’s administration, like every other new government, wishes to impose its own spending plans, and human spaceflight has never been high on its list of priorities. The existing plan for human spaceflight sets NASA on a path that will lead it to consume what one insider estimates to be around $100 billion before the programme is complete. It seems entirely prudent, therefore, for the administration to examine whether this is money well spent.

NASA faces substantial challenges. For example, as currently designed, its plans for a system of rockets to replace the shuttle (known collectively as Ares, the Greek name for Mars) do not fit within the funds that are available, and have been criticised for showing too little innovation and even less progress. NASA’s role, some argue, should be the whizzier business of novel plasma-drives and nanotech-based heat shielding—not “Apollo on steroids” as some people have derisively described Ares. Nor is there any sense of how the proposed moon base that would eventually be built, supposedly as a stepping stone to Mars, can be supported financially.

The difficulty, as ever, is to make the agency properly serve the public that pays for it. Few are suggesting that NASA be eliminated, but such questions reflect the struggle for purpose that it has had since the end of Apollo. Its mission is not human exploration for its own sake, nor off-planet colonisation, yet human spaceflight consumes a large chunk of the budget.

At the moment a shift in priorities that would lead to a direct Mars mission seems unlikely. Even if astronauts return to the moon, though, the means of getting them there must still be decided. One alternative to Ares, proposed by the United Launch Alliance, a joint venture of Lockheed Martin and Boeing, is to use modified versions of their existing Delta 4 and Atlas 5 rockets both to go to the moon and to resupply the space station, but at lower cost. And if Ares is cancelled another winner may be SpaceX, a small Californian firm that is building a series of rockets called Falcon. These will be able to fly cargo to the International Space Station—and, if all goes well in the future, people.
SpaceX differs from Lockheed and Boeing in that Falcon is a speculative venture rather than having been commissioned (as Delta and Atlas were) by the government. Many see this sort of true private enterprise, rather than the taxpayer-assisted sort, as the way forward in space. And if that is the case, the eternally difficult question of what NASA is for will soon have to be asked again.

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