cleaning up space junk one piece at a time?

February 22, 2012 — Leave a comment

Here’s an idea from a Swiss lab to clean up the hazardous cloud of space junk hurtling around Earth, a small satellite called CleanSpace One designed to capture and slow down a single piece of orbiting debris until it burns up in the atmosphere. Doesn’t sound very efficient, does it? But since space junk orbits in very different inclinations and at different altitudes, targeting it one object at a time may be the most effective way to clean it up, and we definitely do need to clean it up. Lately, the ISS had to make a few evasive maneuvers to avoid the incoming debris and there have been several satellite collisions resulting in even more shrapnel. If we fly into space without bothering to clean up after ourselves, we may end up plowing a rocket or a spaceplane into an extremely dangerous piece of metal or plastic traveling at roughly 17,500 mph. Right now, using CleanSpace would make clearing out a more or less conservative 60,000 pieces of junk a $648 billion endeavor since the launch costs $10.8 million per satellite, a price tag also known as "no way in hell are we spending that much right now" in both Europe and the United States. To make it a more viable proposition, the Swiss team says it can lower the price by economies of scale and deploy multiple satellites per launch. But will that be enough?

Since the trajectory of each piece of space junk may be different, deploying a swarm of satellites in orbit won’t be easy or necessarily effective unless they’re clustered very closely together, so much so that just a nudge or two will be enough to set them on the right course. Anything more than that and the satellite now has to carry more fuel, which means it will weigh more, which means it will need a bigger, more powerful rocket to carry it into orbit, which will push the launch costs back up. What the Swiss team will be doing is a very careful dance with financial thresholds and that’s only going to come after they can demonstrate that they could successfully deploy a clean-up cluster. As for an initial mission, it would de-orbit a mini-satellite done with its mission and chances are that with proper testing it would fare quite well, well enough to be used for carefully de-orbiting an important or potentially dangerous satellite if required. But when it comes to the cluster deployment approach, why not use a net to engulf traveling space junk and push tens if not hundreds of pieces back to Earth with an extremely strong fabric that would cover the same area as a dozen SpaceCleans? Or just zap them with a very carefully aimed laser from the surface? Or just spray a fine mist that slows tens of miles worth of junk?

But there’s a problem with cleaning up space junk other than scale. Just as easily as one could use a swarm of these tiny SpaceCleans to clean up debris, one could also use them to strategically attack a foreign orbital asset, pulling spy satellites out of orbit or holding an enemy nation’s space station hostage. To avoid that, not a lot of nations are very forthcoming about what they have or don’t have in orbit, which provides some security by obscurity, but also means that a perfectly working spy satellite mistaken for a dead relic would be burnt up in the atmosphere and the military of the country that owns it would have to decide whether to acknowledge it existed and threaten those who de-orbited it with war, or stay silent and swallow the cost of lost assets. That’s not the kind of scenario you want casting its long shadow over a perfectly legitimate and necessary effort, and the only possible solution to that would have to be an international process which determined what pieces of space junk can be cleaned up, how and when, essentially a cleanup by committee. As with many things in the world of science and technology, we know how we could fix a problem but politics and economics stand very firmly in the way and we’d ignore them at our own peril. After all, who wants to start a war by clearing out what seemed to be a perfectly legitimate hunk of junk polluting Low Earth Orbit?