We've been launching stuff into space for nearly 55 years now, and a large percentage of it just stays up there until it comes back down on its own. Debris was always going to be a side effect of all the stuff we have in orbit, but now there are so many bits of space junk around Earth that spacecraft are feeling threatened. Shields up.
Concern over the impact of orbiting debris on space missions has been around for a while, but it ratcheted up again last month when the International Space Station had to move to avoid a hunk of junk ... for the 13th time. A piece of something was headed right for it with the speed of a bullet, so the crew fired the engines for nearly a minute to move the ISS orbit 1,000 feet higher. That doesn't sound so bad, until you realize the piece of junk they were moving to avoid was only about four inches in diameter.
That's right, something that small can cause serious damage, even to something as big as the ISS. And if that's not scary enough, NASA estimates that there are about 19,000 similarly sized bits of junk in orbit, along with about 500,000 pieces of junk between .4 and four inches in diameter. As for as pieces smaller than that, there could be tens of millions of them.
Where does it all come from? Well, there are a lot of sources, but the amount of space junk in our orbit increased dramatically in 2007 when the Chinese space agency tested some new anti-satellite technology by destroying an orbiting satellite they didn't need anymore. Two years later the count went up in a big way again when an Iridium communications satellite and a Russian satellite collided.
It's a big planet, so all this cosmic schmutz only amounts to about a 1 percent chance that any of it will hit a spacecraft. But all it takes is one hit, and a craft could be so critically damaged that it too will become space junk, which increases the chances of future craft getting hit, and so on until we're a planet surrounded by a permanent junk cloud that we can't fly past. That's the worst-case scenario, of course, but you understand why it's so important to be careful.
Where's that giant maid from Spaceballs when you need her?