How does the International Space Station dodge space junk?
The 200-ton orbiting behemoth can get out of harm's way, but not very quickly.
- By Joe Pappalardo
- AirSpaceMag.com, March 01, 2007
(Page 2 of 2)
But what about bona fide emergencies? How quickly could the station dodge a piece of space junk?
Bacon, who has been part of the ISS program since he joined NASA 16 years ago, says that even with advanced warning, engineers wait until "the last minute" to fire thrusters to avoid a potential threat. The last minute means 1.5 orbits, or about 135 minutes, from the predicted point of collision. That gives the ISS two chances to move over or under any incoming danger. Waiting also allows the Space Control Squadron at Cheyenne Mountain in Colorado, which tracks debris in orbit, to refine its predictions about a possible collision. Changing orbits is very disruptive to the work done on the station, and "nine times out of ten you don't have to," Bacon says. "You don't want to maneuver if you don't have to. It's a big deal to fire the engines."
And there are no guarantees—Bacon notes that Cheyenne Mountain can track only objects the size of baseballs and larger. The ISS is designed to survive collisions with objects the size of peas and smaller. That leaves plenty of space junk large enough to cause damage and too small to spot. So even with the ability to move out of the way, luck will continue to play a part in keeping the station safe.