As long as people have looked up at the night sky, they have wondered whether humanity is alone in the universe. of places close enough for people to visit, Mars is the only one that anybody seriously thinks might support life. The recent confirmation of a five-year-old finding that there is methane (a colorless gas with no smell) in the Martian atmosphere has therefore excitedthe hopes of those scientists who study the outer space. These sources are probably geological but they might, just, prove to be biological. The possibility of life on Mars is too thrilling for mankind to ignore. But how should we explore such questions—with men, or machines? George Bush"s adniinistration strongly supported manned exploration, but the new administration is likely to have different priorities—and so it should. Michael Griffin, the boss of NASA, a physicist and aerospace engineer who supported Mr. Bush"s plan to return to the moon and then push on to Mars, has gone. Mr.Obama"s transition team had already been asking difficult questions of NASA, in particular about the cost of scrapping parts of the successor to the ageing and old-fashioned space shuttles that now form America"s manned space program. That successor system is also designed to return humans to the moon by 2020, as a stepping stone to visiting Mars. Meanwhile, Mr. Obama"s administration is wondering about spending more money on lots of new satellites designed to look down at the Earth, rather than outward into space. These are sensible priorities. In space travel, as in politics, domestic policy should usually by far outweigh foreign adventures. Moreover, cash is short and space travel costly. Yet it would be a shame if man were to give up exploring celestial bodies, especially if there is a possibility of meeting life forms—even ones as lowly as microbes—as a result. Luckily, technology means that man can explore both the moon and Mars more fully without going there himself. Robots are better and cheaper than they have ever been. They can work tirelessly for years, beaming back data and images, and returning samples to Earth. They can also be made germless, which germ-infected humans, who risk spreading disease around the solar system, cannot. Humanity, some will argue, is driven by a yearning to boldly go to places far beyond its crowded corner of the universe. If so, private efforts will surely carry people into space. In the meantime, Mr. Obama"s promise in his inauguration speech to "restore science to its rightful place" sounds like good news for the sort of curiosity-driven research that will allow us to find out whether those columns of methane are signs of life.
单选题
According to the first paragraph, men want to explore Mars because they