Ever since getting things into orbit became a routine task the amount of stuff we’ve left floating around us in space has increased exponentially. Typically the debris that surround us are made up of the upper stages of rockets, disused satellites that can’t/won’t de-orbit for some time and, worst of all, innumerable other bits of miscellanea that are the result of things crashing into each other. This is the beginnings of a terrible self inflicted disease called Kessler Syndrome whereby the lower orbits are so littered with junk that launching anything becomes nigh on impossible, save for some drastic changes in technology. Thus it’s in our best interests to come up with some workable solutions to this issue and the engineers at the Japanese Aerospace Exploration Agency (JAXA) have come up with a very interesting solution.
Whilst most of the debris surrounding Earth will eventually make its way back down the time frame in which it will do so varies from years to centuries. Since the orbits are unstable it’s likely that they’ll change drastically over time and this means that the chance that they will collide with another bit of debris increases quite dramatically. This is the real crux of the issue as collisions of this nature create much more debris than their individual parts alone (it is also why all the collective space faring nations were a rather pissed at China for testing their anti-satellite missile). Whilst there’s not much we can do for the numerous small bits of debris orbiting Earth there’s a lot we can do for a specific type of space junk, specifically the upper stages of rockets, and this is what JAXA’s latest development targets.
The team at JAXA’s Innovative Technology Research Center have devised what they’re calling an electrodynamic tether to help combat the space debris issue. It consists of a small space craft, one could imagine something of cubesat size, that attaches to a large piece of debris via a long electrically conductive tether. Then, by virtue of the fact that Earth has a magnetic field and the tether is conductive, Lorentz forces then act to drag the two satellites back down to Earth. It’s a rather ingenious way of getting the junk to deorbit as it doesn’t rely on carrying massive amounts of propellant, making the craft infinitely smaller and far more efficient. It might only tackle a specific subset of the debris in space but their calculations show that this should be enough to prevent a runaway Kessler syndrome situation.
Probably the coolest thing about it, at least for me, was the preferred way of attaching the tether to the target. They have explored some regular options, namely coasting up to the craft and attaching it with a robotic arm, but since their targets are going to be the usually thin walled upper stages of craft they’re instead opting for a harpoon that will penetrate the hull of the craft. So in the future we could have a swarm of harpoon carrying cubesats orbiting us, ensuring that any large bit of space junk is brought to the fiery demise it so rightly deserves.
Of course this doesn’t mean the problem is completely solved but this could be enough of a stop gap solution whilst we figure out better ways of cleaning up our lower orbits. It’s not going to be an easy problem to solve, the energies required to get everything up there in the first place ensure that, but things like this show that there are highly efficient ways of dealing with it. All that’s required is for us to find them and, hopefully, deploy them before its too late.