But what do you do when you find an asteroid targeting Earth? If you remember the movie "Armageddon," the solution was to send Bruce Willis and a team on two space shuttles to blow it up.
"People have these crazy ideas because they get their physics from Hollywood movies," said Lu. "Never get your physics from Hollywood movies. In general, you only need to change the velocity of an asteroid by a millimeter per second. That's about the speed an ant crawls."
Lu proposes sending a spacecraft that would essentially act as a tractor – nudging the asteroid off its crash course with Earth.
"All you need to do to do is run into it with a small spacecraft, or tug at it with a space tractor," said Lu. "We are not powerless to prevent this, that part is reasonably well understood, what we need to do is find out where the asteroids are and that is what we have to solve first."
"When you look at the Earth from space, especially as I did, when you fly around the planet every hour and a half, you see the whole Earth," said Schweikart, who flew on Apollo 9 in 1969. "You identify with the whole planet and you realize that this is such a precious place."
The B612 Foundation's Sentinel telescope is envisioned as a worldwide project – one which would search the solar system for years, mapping what's out there.
"Once it makes its three dimensional map of the solar system, then that map is good for about 100 years," said Lu, who spent six months on the space station in 2003. "Sentinel can go away because we will know where those things are; if we know about it we can do something about it."