Space Junk Hunter-Killer Satellites Are On The Way

A Japanese-Australian team has come up with a concept of launching a fleet of plasma-firing satellites that will push debris out of orbit.

We’ve known for a while now that Low Earth orbit is getting cluttered. Unsurprisingly, this isn’t a good thing. According to the US Department of Defence, there are upwards of 29,000 large bits of space junk and nearly a million smaller peices, which pose a very real threat to satellites.

What is Space Junk?

Space junk is made up of bits of old satellites and other man-made debris that’s been left floating in orbit. Current satellites often have to perform evasive actions to avoid crashing into bits of it. If a satellite were to collide with a piece, it’s force would be the equivalent of an exploding grenade and it could shatter the satellite into around a million pieces. This could, in turn, pose a threat to the Earth.

Millions of pieces of space junk, many only the size of a fleck of paint, orbit the Earth. Credit: NASA


What Can We Do About it?

This has been an important question for a while now. ESA (European Space Agency) track the larger pieces of space junk and has a team dedicated to keeping the satellites out of harm’s way. As you can imagine, this ain’t cheap. In the past ideas of how to clean it up have focussed around firing nets to catch larger pieces, but this is ineffective at catching smaller pieces and a very slow process.

Now, a Japanese-Australian team has come up with a concept of launching a fleet of plasma-firing satellites that will push the debris out of orbit. The plan would be to slow down the objects enough that they fall closer to Earth’s orbit, where the friction would cause them to decay rapidly.

(a) Concept for space debris removal by bi-directional momentum ejection from a satellite. (b) Schematic of a magnetic nozzle rf plasma thruster having two open source exits. (a) When plasmas carrying momentum fluxes F1 and F2 are expelled from two axially opposite satellite exits, the respective forces shown by the horizontal arrows F1 (pointing to the left and providing the acceleration of the satellite with respect to the orbit velocity) and F2 (providing the deceleration) are generated and used to adjust the satellite velocity relative to the debris. Continuously imparting momentum flux F1 to the debris (horizontal arrow F1 pointing to the right) will cause its deceleration, final re-entry into the Earth atmosphere and natural burn up. (b) The open exits magnetic nozzle rf plasma thruster forming the single electric propulsion device where control of the momentum flux imparted onto the debris is obtained via the control of the plasma momentum fluxes ejected at each open exit using variable external parameters (solenoids currents and propellant gas flow rates).


Cool. What’s the Problem?

The force of the plasma ray would push the satellite away from the debris before it could finish its job. The solution that’s currently being worked on, is to eject another, equally powerful ray of plasma from the other side of the machine, to keep it balanced. It hasn’t yet been tested in space, but in theory, it seems very possible.

The main focus at the moment is stop more space junk being put into orbit, so future generations don’t have to deal with it. That doesn’t deal with the stuff we have now, though. Hopefully, this plasma ray is the solution we’ve been waiting for.

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