Chemistry and Physics

Practising The Clean-Up Of Space

Pictorial representation of planet earth surrounded by thousands of satellites in low earth orbit
Christina Giallombardo

Looking up at the night sky with the naked eye and seeing nothing but darkness and a few stars, it’s hard to imagine the sheer volume of space debris (also known as space junk) orbiting the Earth.

The space junkyard gives us a glimpse back in time. The orbiting debris is a disarray of past missions to space, including 1950 discarded rocket stages and defected satellites, as well as a plethora of shrapnel.

The near 9000 tons of space debris orbits Earth in a Low Earth Orbit (LEO), which is approximately 1000-160km above Earth. The problem is that this debris is not stagnant, but moving at around 18,000 miles per hour, meaning it poses risk to vital operating systems also in a LEO, such as telecommunications and weather forecast satellites. The International Space Station (ISS) also orbits in a LEO, also causing a threat to human lives. Impact reported on this problem during Space Week last year.

If space debris is so dangerous, why is it allowed to accumulate? One reason is that the guidelines put in place regarding the removal of retired missions out of orbit within 25 years have been poorly followed, leading to a build-up of junk.

Another reason is because it’s not as straightforward as it seems. A large problem is that only about 26000 debris objects are actively monitored, whilst there are nearly 1 million smaller fragments (1-10cm in size) that are near impossible to track.

The End-of-Life Service by Astroscale Demonstration (ELSA-D) was devised as an effort to tackle the problem of space junk. ELSA-D, by the Japanese company Astroscale, was launched on 22nd March 2021 at 06:07 GMT from the Baikonur cosmodrome in Kazakhstan.

The mission consists of two satellites, a 1750kg ‘Servicer’ and a 17kg ‘Client’, attached to a Russian Soyuz rocket which was painted white and blue to mark the 60th anniversary of the first human in space, Yuri Gagarin.

The 6-month long mission is designed to simulate an approach to a stable piece of junk, attaching to it, then lowering the debris into Earth’s atmosphere where it can burn up.

The flight lasted five hours as it had to deposit 38 small and medium-sized international satellites into three different orbits roughly 500-550km above Earth. Once in LEO, the Servicer and Client will separate and begin a game of cat and mouse.

Astroscale wants to act as a sort of “breakdown service” for space

The Servicer will use built-in sensors to chase down the Client and attach to it using magnetic docking plates, before releasing it and beginning the chase again, with the difficulty of the hunt increasing as time goes on.

Despite the company deploying the mission being Japanese, the Client spacecraft was manufactured by Surrey Satellite Technology Limited (SSTL) in the UK. Two British-made satellites also joined the mission and were made by Open Cosmos on the Harwell science campus in Oxfordshire.

If the mission proves successful, Astroscale wants to open their service for commercial use. Harriet Brettle, head of business analysis at Astroscale, said they want to act as a sort of “breakdown service” for space.

The commercial-use missions will be named ELSA-M where M stands for multi-client, meaning a Servicer will capture up to three Clients and pull them down to lower orbits where they can easily burn up upon re-entering the atmosphere.

Not only is debris thrown away and discarded on Earth, but it’s now surrounding Earth in a junk halo. The Astroscale mission to deal with the junk is just one of many projects that are undertaking the task of cleaning Earth’s orbit and hopefully provide a safer and brighter future for space exploration.

Christina Giallombardo

Featured image by Hopeful in NJ from Flickr. Image licence found here. No changes made to this image.

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