Saturday, April 14, 2018 by Edsel Cook
Man the harpoons! As a part of a larger effort to clean up space debris, Airbus is testing a space-age spear that can capture rogue satellites, according to an article by the BBC.
The space harpoon and its attached tether will be loaded aboard disposable spacecraft that hunts for rogue or redundant satellites. Once it hooks a target, the hunting vehicle will dive into the atmosphere, dragging the other craft to burn to destruction.
Airbus developed the concept in response to the ever-increasing number of old hardware stuck in orbit. More than 20,000 pieces of space junk – the smallest of which measures 10 centimeters in size – constantly run the risk of hitting active satellites.
One of the Moby Dicks of space junk is the inactive Envisat satellite. The largest non-military satellite in the world, it’s the size of a bus and weighs eight tons.
Envisat died without warning in 2012. Airbus is ensuring its newest iteration of the space harpoon can capture the massive object. (Related: DARPA is focusing on space as a the new great battlefront.)
“Envisat is the outlier. If we can design a harpoon that can cope with Envisat, then it should be able to cope with all other types of spacecraft including the many rocket upper-stages that remain in orbit,” said Alastair Wayman, an advanced project engineer at Airbus.
“The harpoon goes through these panels like a hot knife through butter. Once the tip is inside, it has a set of barbs that open up and stop the harpoon from coming back out,” said Wayman.
“We’d then de-tumble the satellite with a tether on the other end,” he finished.
Other capture methods are much more complex and require far greater effort. In comparison, a harpoon can be aimed and fired with no fuss.
“Many of these targets will be tumbling and if you were to use a robotic arm, say, that involves a lot of quite complex motions to follow your target,” Wayman explained.
According to him, all a harpoon-equipped spacecraft has to do is to maintain its distance, let its target rotate beneath it, and fire its projectile at the right moment. The speed and simplicity of the process greatly reduces risk.
The chase vehicle will use its own thrusters to stabilize its captured satellite. Once it has stopped its target from tumbling, the satellite chaser will tow its prey into the atmosphere.
The European Space Agency is looking at all the available options to decommission Envisat. Airbus expects the first few satellite harpooning missions will be sent after smaller defunct satellites, which will be easier to stabilize and tow.
A smaller version of its space harpoon will be tested aboard a demonstrator satellite called RemoveDebris. Developed at the Surrey Space Center, the tiny experimental vehicle also carries another capture system that uses a net as well as its own target.
Once in space, the RemoveDebris vehicle will release its target before attempting to recapture it using the net and the harpoon. These tests will determine how the two capture systems behave in zero-gravity environments.
According to a Space.com article, RemoveDebris has to bring its own target because laws forbid using space objects owned by another country, even if the object is no longer functional.
Meanwhile, the big space harpoon in Stevenage is preparing for its next development stage. Airbus researchers will fire it at a target 25 meters away, the expected engagement range in a real satellite capture operation for the likes of Envisat.
Find more space technology news on Space.news.