Space harpoon aimed at rogue satellite passes test in Stevenage

PUBLISHED: 13:50 16 March 2018 | UPDATED: 15:31 16 March 2018

An artist's impression of how it will look when the craft carrying the harpoon, right, approaches Envisat in orbit. Picture: Airbus

An artist's impression of how it will look when the craft carrying the harpoon, right, approaches Envisat in orbit. Picture: Airbus

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A space harpoon mission aimed at getting a rogue satellite out of orbit took a big step forward yesterday as it passed a crucial earthbound test in Stevenage.

How the space harpoon will breach the stray satellite. Picture: AirbusHow the space harpoon will breach the stray satellite. Picture: Airbus

The metre-long metal harpoon was tested at Airbus Defence and Space, off Gunnels Wood Road. The goal is to use it to bring down Envisat – an eight-tonne satellite the size of a double-decker bus that stopped working in 2012.

It’s been orbiting the Earth ever since, threatening other vital satellites as it goes.

The test in Stevenage involved using compressed air to fire the harpoon into a panel representing part of a satellite’s structure.

“We fired the harpoon vertically at about 55mph and it hit the bullseye of the target,” said space systems engineer Pete Steele.

The space harpoon at Airbus Defence and Space in Stevenage. Picture: AirbusThe space harpoon at Airbus Defence and Space in Stevenage. Picture: Airbus

“The tip fully penetrated the satellite panel and the barbs deployed as intended.

“We’re now looking at doing a bigger test where we will fire the harpoon vertically over 25 metres, which will demonstrate the accuracy of the harpoon and the ability to withstand the forces required to deorbit the target.”

The plan is for the harpoon to be launched on a spacecraft in the 2020s and carried to within 15 to 25 metres of Envisat, where it will attempt to take hold of the satellite in orbit – with four barbs locking in place after it hits.

The spacecraft will then pull Envisat towards the Earth and slow it down until it deorbits over the Pacific Ocean, burning up as it is dragged through the atmosphere.

“Envisat is currently not controllable,” said Pete.

“If it does collide with another piece of space debris, it could explode in a big cloud of dangerous debris fragments.

“The harpoon hits the target with a force of around 1500g, which is enough to punch straight through the 3cm-thick structure of the satellite.

“After we successfully harpoon the target, we can use a tether attached to a chaser satellite to drag it back into Earth’s atmosphere, where it can be safely destroyed.”

The Airbus project, part of the European Space Agency’s Clean Space programme, follows internal Airbus R&D work and RemoveDebris, another British-developed ESA space junk mission using a net.

There are about half a million pieces of space junk at least as big as a tennis ball orbiting the Earth at 17,500mph.

In 2009, a Russian and an American satellite crashed and produced a cloud of 2,000 fragments big enough to destroy other spacecraft.

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