 “Yes, ladies and gentlemen, welcome aboard NASA’s Space Elevator. We’re going to leave soon. The entire ride will take about five hours, so sit back and enjoy the trip. As we rise, be sure to look out the window. You’ll see the sky change from deep blue to black. It is one of the most wonderful views（景色）you will ever see! ” Does this sound like the Sci-Fi Channel? Well, it’s not. Scientists are thinking that a “space elevator” will be possible toward the end of the 21st century. A space elevator will consist of a long cable (电缆) from the Earth’s surface into space to an altitude(高度) of about 35,786 km. “Elevators” will travel along the cable and move people and loads between Earth and space. One of the greatest advantages is that the cost will be much less. Researchers estimate (估计) that a passenger with baggage at 150 kg might cost only $222! Compare that to today’s cost of around $3.3 million for the same weight. It would make “cheap” space travel possible. Scientists believe carbon nanotubes (纳米管) may be used to make high-strength materials for the cables, although they are still being studied. It was Arthur C. Clarke who brought this idea to the general public. In his science fiction novel Fountains of Paradise, engineers build a space elevator on top of a mountain peak on an island. One day, Clarke was asked a question by a student during his speech. The student asked when the space elevator would become a reality. Clarke answered, “Probably about 50 years after everybody stops laughing.” He’s got a point. When we stop thinking of something as impossible, then we start working on its development. 小题1:Why should passengers in a space elevator look out the window while they are moving into space?
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