DSTL leads effort to de-orbit satellites

Efforts to tackle space debris are underway with an experiment to de-orbit CanX-7, a Canadian satellite that began a controlled descent using space sails in May, 2017.

Space sails
Space sail

CanX-7 is part of the Daedalus experiment, an effort led by scientists at the Defence Science and Technology Laboratory (DSTL) to tackle space junk.

According to NASA, over 500,000 items are tracked as they orbit Earth, yet fewer than 5,000 are operational satellites. Travelling at speeds of up to 17,500mph, relatively small pieces of orbital debris can damage a satellite or a spacecraft.

DSTl says the most congested area sits in low Earth orbit (LEO) where collisions can cause further debris. If this problem is not addressed, space junk threatens to make space exploration and satellite launches impossible. It also poses a hazard to existing satellites, including those used by Britain’s armed forces.

To tackle this problem, the Inter-Agency Space Debris Coordination Committee (IADC) has proposed that all LEO satellites should be de-orbited within 25 years.

De-orbiting rockets can do the job but are expensive. As part of a collaboration with industry, government and academia, DSTL space scientists are leading the exploration of alternative methods.

The Daedalus experiment – part of the Space Situational Awareness Project in DSTL’s Space Programme – is looking at the effect on satellites of Icarus ‘de-orbit sails’. These are made of 25 micrometre-thick aluminium-coated Kapton, which is a high heat-resistant polyimide film. When deployed, the sail increases drag, causing a controlled descent into the Earth’s atmosphere.

With the help of its de-orbiting sail, CanX-7 is expected to burn up in the Earth’s atmosphere in around two years’ time. Two other satellites, TechDemoSat-1 (TDS1) and Carbonite-1 (CBNT1), have been fitted with Icarus de-orbit sails created by Cranfield University and are expected to start their descents later this year.

The experiment results will help to characterise changes in the brightness of the satellite caused by the sail deployment, quantify the drag increase that is due to the de-orbit sail, and critically compare different orbital dynamics models.

DSTL is leading co-ordination of the UK element, tasking sensors to collect data to support Daedalus. Of particular relevance to the military community is the effect that such high-drag satellites have on current space situational awareness sensors and processing systems.

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