“Everybody assumes that if we get somebody that shoots at me in space, we’re going to shoot back in space. Well, that’s a horrible idea,” says Colonel Shawn Fairhurst, the deputy director of Strategic Plans, Programs, Requirements and Analysis at the Air Force Space Command.

“When you blow something up on the ground, it falls back to the ground. If you blow something up in the air, the airplane comes back to the ground,” he says. “The problem is, when you blow something up in space, it creates debris that never comes down.”

We have little ability to control or defend against that debris, which means the potential for collateral damage is high. It doesn’t take much to shred metal when something is moving at 17,000 miles per hour, as objects in low Earth orbit are. A paint chip estimated to be the size of a grain of sand left a quarter-inch pit in a space shuttle window, and the panes must occasionally be replaced because of similar impacts. Something the size of a marble could be devastating to a satellite.