Space harpoons could be the best way to defend astronauts and cosmic travellers from the clumps of junk hovering in near-Earth orbit.
Space junk is increasingly getting in the way of safe space travel—the International Space Station is always having to maneuvre itself to avoid hitting errant lumps of metal flying around the Earth at hundreds of meters per second, and according to the European Space Agency (ESA), there are currently 22,000 objects bigger than a coffee cup currently in orbit despite only 1,100 of those being working satellites.
The BBC reports on a project from space company Astrium UK to tackle this problem using harpoons. These would be fired from dedicated "chaser satellites" that would patrol orbits around the Earth, with handlers on the ground assessing targets over video feeds. When they find a target, the chaser fires and latches onto the rogue satellite—then a propulsion unit attached to the cable fires its thruster, dragging the rogue object down towards a fiery disintegration in the atmosphere.
Harpoons fired from these satellites would be quite small, only 30cm long, because anything too big runs the risk of knocking away a target or even causing it to disintegrate. It has to pierce the aluminium skin of the target, and then latch on with a barb—just like a normal harpoon—but be careful not to create several even smaller pieces of debris from one large piece by, for example, causing an explosion, which would rather defeat the purpose of the exercise.
There's currently something of a boom in organizations planning ways to tackle space junk, which could be said to date to the high-profile and unprecedented collision between two communications satellites in 2009. The ESA has even launched a dedicated Clean Space Initiative to try and find new and innovative ways of preventing a catastrophic buildup of space junk that could make the human use of space impossible.
This is, unsurprisingly, due to the speeds and sizes of these objects—many of them travel in orbit at similar speeds as fast as bullets, and are of a similar size. The more collisions there are, the smaller and more numerous the individual items that need tracking—it's not an easy job, so prevention is definitely the best way to approach the problem. Nasa estimates that there are currently at least 500,000 objects between one and ten centimetres orbiting the Earth; there are more than 100 million objects up there that are smaller than one centimetre.
In February Wired.co.uk reported on one possible solution, the CleanSpaceOne—a satellite designed by the Swiss Federal Institute of Technology that can roam in orbit while grabbing and storing tiny pieces of space debris until, when full, it dives back into the atmosphere to burn up. Nasa has proposed zapping stuff with high-powered lasers as it flies past. Just this week Boeing filed a patent for sending up a satellite filled with heavy gases that, when sprayed on orbital debris, would slow them down enough to make them fall back into the atmosphere.
But imagine, if you will, the year 2151, and a crazed Captain iHab pursuing a white satellite across the cosmos.
It's almost certainly going to happen.