One of the biggest modern threats to spaceflight — apart from politics — is space junk. For each satellite, rocket, capsule, space station, missile, booster, observatory, dog or monkey we put into space, we litter Earth orbit with 5 percent more junk every year.
So it seems we are doomed to failure. There’s currently an estimated 5,500 tons of debris up there, and it’s getting worse. The more active we become in space, the more junk we shed, and it is a hyper-velocity hazard, putting future astronauts and our multi-billion dollar satellite industry at risk.
What’s more, space debris can interrupt satellite communications, possibly even satellite TV signals — we can’t be having that!
Fortunately, various agencies around the world have accurate means of tracking the larger bits of debris, providing some kind of warning should a speeding bit of shrapnel get too close to our orbital real estate. We might not be able to do anything (yet) about the smaller stuff, but UK scientists have come up with a novel idea about how to remove the larger stuff from orbit.
Enter the CubeSail, a modified solar sail designed to bring dead satellites and rockets down to Earth.
The nanosatellite concept, designed by scientists at the University of Surrey and funded by the European space company Astrium, will be launched for space trials in 2011. Inspired by the solar sail — a spacecraft propulsion system that uses the pressure of sunlight to get around space — the CubeSail uses air resistance to slow down its motion.
Unfolding into a 5×5 meter sheet of plastic, the CubeSail is designed to “drag” defunct satellites from orbit, making use of the thin wisps of atmospheric gases at orbital altitudes. Although the density of air molecules is low, it’s enough to make the sail act like a parachute, slowing it down, dragging the dead satellite to a fiery reentry much sooner than it would have done otherwise.
“Protecting our planet and environment is key for sustainable growth,” said Vaios Lappas, lead researcher on the project. “CubeSail is a novel, low cost space mission which will demonstrate for the first time space debris/satellite deorbiting using an ultra light 5 x 5 sail stowed and supported on a 3 kg nanosatellite.”
Although this system is intended to be attached to future missions that require a safe (and cheap) means of being removed from orbit, I can imagine this kind of system being attached to some kind of “seek and destroy” robot, taking out old orbital debris.
The CubeSail could be launched alone and under its own power and guided to orbital debris being tracked from the surface. Once the robot “docks” with the debris, it opens its sail, pulling the junk from space.
Like with many space technologies, I also wonder if such a sci-fi concept could have a military application.
Both the USA and China have demonstrated that they can “shoot down” satellites with ground-launched missiles, filling low-Earth orbit with millions of pieces of smaller bits of debris, ultimately making Earth orbit impassible (there’s no military advantage in filling space with junk after all). Perhaps anti-satellite weaponry could be more passive, sending ground-controlled CubeSails into orbit, seeking out, attaching to, and ultimately destroying enemy satellites but without the mess?
Images: The space junk problem (NASA) and the the CubeSail concept (ESA/Univ. of Surrey/Astrium).