'Janitor satellite' would clean up space junk
- By Kevin McCaney
- Feb 24, 2012
Swiss scientists are building a “janitor satellite” to help clean up the burgeoning problem of space junk, but unless the project catches on and attracts a lot of customers, it might not make much of a dent in the problem.
A team at the Swiss Space Center at EPFL in Lausanne are developing CleanSpace One, the first of what they plan to be a family of space junk-cleaning satellites that will capture debris orbiting the Earth and bring it back to burn up in the atmosphere.
The $11 million project is dealing with a real concern. Inoperable satellites, broken pieces of spacecraft and other debris has been gathering in the upper atmosphere for 50 years. NASA tracks more than 16,000 pieces larger than 10 centimeters in diameter and estimates there are 500,000 pieces smaller than that.
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At orbiting speeds near 17,500 mph, even small pieces can cause damage. In February, 2009, an U.S. Iridium satellite was destroyed when it collided with a defunct Russian satellite. Crews in the International Space Station frequently must adjust their orbit to avoid incoming junk and in June 2011 had to take shelter in inside two Soyuz capsules when debris got a little too close. In September 2011, a railroad car-sized UARS satellite fell to Earth, though it landed safely in the ocean.
That same month, the U.S. National Research Council of the National Academies issued a report saying that the space junk problem had reached a “tipping point” at which low-Earth orbit was becoming too risky. Even though spacecraft can maneuver to avoid large pieces of debris, orbital paths are becoming dangerously cluttered with debris of all sizes, the report states.
In trying to tackle the problem, scientists at the Swiss Space Center are starting small, although they have some technical challenges to work out.
CleanSpace One, which in EPFL illustrations looks like a storage trunk, will be 30-by-10-by-10 centimeters (a foot long and about four inches on each other side), according to EPFL’s announcement of the project. EPFL hopes to launch it within three to five years, and its first target will be one of two out-of-service Swisscube picosatellites launched in 2009 and 2010.
After its launch, CleanSpace One will have a tricky job. It will have to adjust its trajectory, using a new type of ultra-compact motor designed for use in space, to match its target’s orbital plane while at orbiting speed, EPFL said. It will then reach out with a gripping claw, grab the target and pull it back in. Then CleanSpace One will “de-orbit” the target by returning to the Earth’s atmosphere, where they will both burn up.
One down, 499,999 to go — or so might seem at first.
But although the maiden voyage might seem like cleaning up after Mardi Gras by taking trash to the landfill one piece at a time, EPFL is using the first flight to develop the prototype for a fleet of space janitors it expects to be “designed as sustainably as possible [and] able to de-orbit several different kinds of satellites,” Swiss Space Center Director Volker Gass said in the center’s announcement.
The center is hoping to sell such satellites once they get into larger scale production and, if customers find the price is right, it could mark a step toward cleaning up the orbital paths.
The Swiss aren’t the only ones looking to solve the problem, though. NASA is researching a couple of ideas: using solar sails to power orbiting cleanup crafts, and using lasers to slow down debris enough that it would re-enter the atmosphere and burn up. And the Defense Advanced Research Projects Agency is working on the possibility of using space-borne robots that would salvage parts from old satellites to build new ones while in orbit.
In the meantime, NASA and the Air Force have been working on improving their ability to track debris, in order to better avoid space traffic accidents.
Kevin McCaney is a former editor of Defense Systems and GCN.