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Fishing Space Debris from Orbit

Millions of pieces of space debris are orbiting Earth dating back to Sputnik-1 in 1957. Could we use fishing nets, harpoons, and sails to reel them in?
Almost 5,000 launches since the beginning of the space age have left orbits littered with defunct satellites, parts of rockets, fuel tanks, tools lost by astronauts, and other fragments which threaten to damage and destroy active spacecraft. Needless to say, space junk is a serious concern for us at Surrey US and for the wider space community.
Cerise mission
As more satellites are launched every year, collisions are becoming increasingly likely. In low Earth orbit (LEO) objects move at around 7.5 km/s (the equivalent of traveling from Denver to Washington, D.C., in about 5 minutes). This speed means that if two objects collide, they will create thousands of other pieces of debris, as happened with the 2009 collision between the Russian Kosmos 2251 and U.S. Iridium 33 satellites.
Surrey encountered the problem first hand when a piece of debris from an Ariane rocket severed the gravity gradient boom of the Cerise mission just one year after its 1995 launch – this was the first verified case of two objects colliding in space.

Scientists worry about a cascade of collisions known as the Kessler Syndrome, where the amount of debris increases exponentially, with the potential to seriously impede opportunities for new missions and degrading, or eventually, stopping the vital services satellites provide.

National and international space agencies around the world are gradually defining and bringing into action space debris mitigation measures. Best practice dictates that satellites should have some ability to maneuver into a re-entry trajectory at end of life to burn up in the Earth’s atmosphere within twenty-five years. We attempt to comply with these guidelines for all of our missions. Our plan is to ensure that whenever spacecraft with propulsion are launched, sufficient fuel is retained until the end of the mission so that it can be removed from “busy” orbits, lessening the chances of a future collision. 

However, not all missions manage to adhere to these mitigation guidelines. The eight-ton Envisat satellite, for example, lost contact with ground controllers in 2012 and is now stuck in an orbit and estimated to take 150 years to re-enter the atmosphere. Until it re-enters, this object and others like it will pose a large and ongoing risk to other satellites and the services that they deliver. 

It is clear that both mitigation and active removal of large debris objects from orbit are necessary to control the space debris problem. Currently, the best estimates suggest we need to remove from five to ten objects from the busiest orbits every year to stabilize the number of objects orbiting the Earth and avoid the onset of a Kessler Syndrome scenario.

Developing de-orbit technologies has never been more urgent, and the race is on to find a suitable solution to the space debris problem. Surrey’s TechDemoSat-1 space technology demonstration mission due for launch in 2014 will be flying a deployable de-orbit sail to drag the satellite back into Earth’s atmosphere for burn-up after the end of the mission and demonstrate a system that will be applicable to larger satellites and other objects in the future. Surrey is also currently working on a satellite design that carries a net-based capture system to catch debris and tow it down into Earth’s atmosphere where it will burn up and be destroyed. This is a simple system that hopefully won’t have to be tailored to each individual item of space debris, making it cost effective over the long term. This is not the only debris removal project that takes inspiration from fishing – another idea is to harpoon threatening debris from close range and pull it downwards to burn up in the atmosphere using a propulsion system. Other concepts being developed for space debris removal range from using lasers to gently “nudge” debris into new orbits, to robotic arms and even grasping “tentacles.”

Image: Cranfield de-orbit sail on TechDemoSat-1

There is no quick and easy solution to space debris, but it is a problem we need to address if we are to protect our valuable resources in space. Cooperation of the entire global space community in finding a solution is the only way to make progress in preventing collisions. And the longer we wait, the more likely it is that we run the risk of a cascading Kessler Syndrome.


12 December 20130 Comments1 Comment

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