They're really not that close together. If you were flying through space, you'd have a fairly difficult time determining that you were in an asteroid field whe

They're really not that close together. If you were flying through space, you'd have a fairly difficult time determining that you were in an asteroid field when you reached one. Albeit some asteroids do travel in 'families.' Dr. Marc D. Rayman on the Dawn Project: Dawn will travel 7.7 astronomical units (AU), or nearly 1.2 billion kilometers (almost 720 million miles), to its July 2011 rendezvous with Vesta. Yet in all that time, and across all that distance, the closest the probe will come to a catalogued asteroid is 1.0 million kilometers (greater than 600 thousand miles), or more than 2.5 times the distance between Earth and the moon.