Instrumentation And Control

摘要

When the apollo astronauts explored the lunar surface,getting around wasn't as easy as it lookeed.Even though the astronauts limited their roving to a few acres close to the lander, they often had trouble navigating. Visual clues to one's location that we on Earth take for granted, such as the apparent size of a car in the distance or the texture of grass on a lawn, were entirely absent. What looked like a good-size rock in thernmiddle distance could turn out to be a giant boulder much farther away.rnWithout some sort of positioning system, an astronaut on missions NASA hopes to begin sometime in the next decade could become dis-oriented, or even lost.