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5组文字，将其分别放回文章原有位置，以恢复文章原貌。 Should the U.S. halt human space flight
The Columbia accident has revived the debate on whether the
rewards of
human space exploration are worth the
risks. No. I was a teacher when men first landed on the moon in
1969, and I remember how it moved my students and this country. (46)
And we haven’t ventured outward since then. That’s 30 years too long!
America’s human space-flight program is adrift, with no clear vision or goals
beyond the completion of the International Space Station. I want
NASA to establish a phased series of goals over the next 20 years, including
human visits to asteroids that cross the Earth’s orbit, establishing a research
and living facility for humans on the moon, and human expeditions to the surface
of Mars and its moons. (47) . An astronaut is
today’s Christopher Columbus, who sailed into the unknown and discovered the
Americas. The knowledge we gain from having actual people exploring can never be
replaced by robots. (48) Robots are useful, but humans can do
things that robots can’t. The real obstacle we face in
overcoming the drift in the nation’s human space-flight program is not
technological and it’s not financial. (49) .
The lesson from the Columbia accident is not that humans don’t belong in
space. (50) . A Instead, we should honor the memory
of the lost astronauts by pushing our exploration of space future. B
Astronauts are key to this expanded exploration. C It’s the lack
of commitment to get started. D Until then, we should stop risking
people’s lives by sending them into space. E It is now more than 30
years since the last American left the surface of the moon and returned to
Earth. F Our ability to send humans into space and have them return
gives us amazing information about ourselves and our universe.