美国科学家预言,未来替人类执行空间使命的航天飞行器有可能缩小到能放进一个人的手掌里。这种微型航天器上安装的全部科学仪器并在一起也许只有火柴盒那么大,推动这种航天器的火箭不是今天使用的庞大而笨重的化学燃料火箭,而是一种轻型的离子发动机。 这种微型航天器由于发射成本低廉,因而可以频繁地被发射上天,有时候甚至可以一次把好几个微型航天器送上空间,让它们共同执行一项使命。 美国宇航局局长丹尼尔·戈尔丁已向美国喷气推进实验室的科学家们提出了要求,要他们为下个世纪的人类空间探索提出一个符合“多快好省”的构想。美国宇航局的 American scientists predict that in the future the spacecraft for the implementation of human space mission may be reduced to the spacecraft can be placed in a person’s palm. Instead of the bulky, heavy chemical fuel rockets that are used today, all the scientific equipment that is installed on such a small spacecraft may be just as big as a matchbox, the rocket that propelled the spacecraft is a lightweight ion engine. Because of their low launch cost, these tiny spacecraft can be launched into the sky frequently, and sometimes even several miniature spacecraft can be brought to space at once, allowing them to jointly execute a mission. NASA Administrator Daniel Goldin has asked scientists at the U.S. Jet Propulsion Laboratory to ask for a concept that would “make for a better future” for human space exploration in the next century. NASA’s