spaceSpace and Physics

Mission To Clean Up Space Junk Begins, Complete With A Net And Harpoon

This illustration from the European Space Agency depicts a small portion of the thousands of known space debris objects and satellites currently orbiting Earth. ESA/Flickr

An experimental satellite was launched into space onboard a SpaceX Falcon9 rocket on April 2. Its mission? Clean up the more than 21,000 known pieces of junk that are currently locked in low orbit around the Earth.

Traveling at up to 28,200 kilometers per hour (17,500 miles per hour), any object larger than 1 centimeter (0.4 inches) poses a constant threat to satellites, manned space stations, and mission vehicles. And sadly, our floating dump contains pieces of detritus as large as double-decker buses.


Other than constantly tracking the movements of these objects, little has been done to take them out of orbit – until now. RemoveDEBRIS, developed by an international research group led by the Surrey Space Centre at the University of Surrey, UK, features two possible junk-snaring technologies that will begin testing by International Space Station (ISS) astronauts several weeks after the rocket docks on Wednesday.

The self-contained, camera and video-equipped, 100-kilogram satellite will be assembled inside the ISS then placed in orbit outside of the station by a robotic arm.

First up for evaluation is RemoveDEBRIS’ net capture technology, where, as the name suggests, a projectile net will target an artificial piece of junk (a 10-centimeter cubesat with a larger, inflatable balloon) launched from the unit. If everything goes according to plan, the net will wrap around the cubesat and balloon, forcing the objects to leave orbit (and consequently burn up on re-entry).

Next, the RemoveDebris unit’s automated vision-based navigation system for characterizing and tracking space junk will be evaluated by sending a second cubesat.


The real fun will pick up when the second junk-snaring method, a miniature harpoon, is fired at the second cubesat in order to knock it from orbit.

And last but not least, in order to avoid becoming space junk itself, the RemoveDebris platform must show that it can get itself out of orbit when its testing mission ends. To achieve this, the unit will deploy a large sail off the back that will catch on scattered air molecules from the top of the atmosphere and create drag. This, in turn, will quickly pull the unit back toward Earth.

Once these four phases have been completed, the team will review which parts of the mission were successful, and which need improvement.

“All these different technologies have their advantages and disadvantages," principal investigator Professor Guglielmo Aglietti told the BBC. "For example, the ones we are testing – the net and the harpoon – are simple and low cost, but could be considered more risky in certain circumstances than a robotic arm.


"On the other hand, if your piece of debris is spinning very fast, it becomes very difficult to capture it with a robotic arm and an approach with a net could work better."

[H/T: The BBC]


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