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Some people, in all seriousness, say that
humans will be living in space within the next
hundred or so years. Planet Earth will be crowded,
dirty and lack of resources. A sort of exodus --71.
(移居) of mankind will begin.
Spaceships will be assembled so that they
revolve around the earth. Some may orbit around
Mars. These space stations will be serviced by
space buses. We saw the first space bus launch in --72.
April 1981. This was "Columbia", it made several --73.
orbits around the earth and then returned, landing
on a huge dry lake bed in California. "Columbia"
will be used again. previous spaceships have
been abandoned, only the nose cone being used
to bring the crews back to earth. --74.
Upon established, each space station will --75.
generate its own atmosphere and have its own
agriculture. it will need to rotation to provide --76.
an artificial gravity; people will be forced inwards --77.
from the center by centrifugal（向心的）force.
The moon and Mars could become new sources of
new materials. Driving through space will no --78.
longer need Earth fuel-the energy would come
from the sun. This energy would be converted from --79.
electricity to work magnetic rockets.
That all sounds quiet fantastically but, with --80.
the rapid development of modern technology, who
knows about what the future holds?
