91色情片

Robert Zubrin鈥檚 The Case for Mars (The Free Press, New York,
拢16.99/$25, ISBN 0 684 81930 9) is convincing. He suggests
colonising the planet by a relatively cheap and small-scale operation called
Mars Direct. The first explorers to arrive on Mars would travel in the nose
section of a space ship already available, and then use Martian materials to
make rocket fuel for the return journey. Later, materials for life support in
settlements on the surface could be made in the same way, followed by complete
鈥渢erraforming鈥� of the planet for human expansion there. Zubrin is practical and
has his feet firmly on the ground鈥擬artian, that is. He is also a clear,
fluent writer and his enthusiasm is catching. Let鈥檚 go.