大的风险。伴随着阿姆斯特朗那句如今已经非常有名的话："这是一个人的一小步，但是整个人类的一大步"，一个梦想实现了。三位宇航员都顺利返回地球，他们当年使用的计算机远不及现在普通学生使用的电脑高级。

在接下来的几年里，又有几艘宇宙飞船进入太空，但是单程宇宙飞船非常昂贵，因为它们只能被使用一次。人们对每天要花掉美国1 000万美元的太空旅行计划不再那么热衷了。这种情况一直持续到航天飞机的出现--那是一种可以被用来进行多次旅行的航天器。第一个到达太空的航天飞机是"哥伦比亚号"--于1981年4月12日发射于肯尼迪航天中心。这次飞行的目的是测试这种新的飞行器，看其是否能够安全进入轨道、返回地球并且安全着陆。距离"阿波罗11号"历史性的飞行仅仅十年多的时间，这次航行取得了成功 ，"哥伦比亚号"在控制下以飞机着陆的方式安全地返回了加利福尼亚。这次飞行开辟了宇宙航行的新纪元。　　

By the time⑳ the Challenger took off in 1986, the world seemed to have lost its fear and wonder at the amazing○21 achievement of people going up○22 into space○23. But this was going to be a special flight and so millions of people tuned○24 in to witness○25 the take­off on TV○26. An ordinary teacher, Christa McAuliffe, 37, who was married with two children○27， was to be the first civilian in space. She was going to give two fifteen­minute lessons○28 from space. The first was to show the controls of the spacecraft and explain how gravity worked○29. The second was to describe the aims of the Challenger space programme. Christa hoped to communicate○30 a sense of excitement and create○31 new interest in the space programme.

Sadly○32， she never came back to her classroom again, ○33as the shuttle exploded○34 just over a minute after taking off in Florida and all seven astronauts were killed.

The world was in shock○35 - maybe they assumed○36 this space flight would be no more dangerous than getting on○37 an aeroplane. But how wrong they were - in one moment excitement and su ccess turned into○38 fear and disaster. It was the worst space accident ever. As one Russian said at the time○39， "When something like this happens we are neither Russians nor○40 Americans. We are just human beings who have the same feelings○41."

⑳by the time"到......时候"，引导时间状语从句。

○21amazing adj.惊人的，令人吃惊的

amaze v．使吃惊　amazed adj.吃惊的，惊奇的

amazement n．惊愕，惊异

○22go up 上升

○23people going up into space 是动名词复合结构，作of的宾语。

○24tune/tjuːn/v.收看(电视)；收听(广播)

tune in (to sth.)收听(收音机广播节目)；收看(电视节目)

○25witness/'wItnəs/v.目击，亲眼看见；亲身经历

○26to witness the take­off on TV是动词不定式短语作目的状语。

○27who was married with two children 是非限制性定语从句。

○28give lessons 上课，讲课

○29work v．此处意为"起作用"。