随着21世纪的即将到来，到太空旅行仅仅是宇航员特权的时代也将要过去了，目前在美国只要交纳9．8万美元就可以申请预约到太空去旅游。不过参加这种旅游的条件是身体健康、有银行存款和一定的勇气。因为这在美国宇航局的太空飞行都难以对安全性进行预测，人们仍然没有忘记“挑 With the advent of the 21st century, the era of space travel as an astronaut’s privilege will soon pass. At present, the United States can apply for an appointment to travel in space for as long as 98,000 U.S. dollars. However, the conditions for participating in this kind of tourism are good health, bank deposits and some courage. Because it is hard to predict the safety of NASA’s space flight, people still have not forgotten that "pick