The space industry – and space junk – is booming, literally. Every year, a handful of satellites inexplicably explode, slowly filling heavily trafficked space lanes with deadly debris.
The International Space Station has had to take evasive action more than 32 times since it settled into orbit in 1999. Last December, a tiny fragment punched a hole in the Soyuz return capsule docked there, causing it to vent its atmosphere.
“It doesn’t matter what the size is if it’s travelling 7.5km a second, it’s a huge danger to anyone or anything up there,” says Harrison Box, founder of the orbital “street sweeping” startup Paladin Space.
The problem is such a concern for space agencies and commercial space firms that stopping it from growing has become a high priority.
Read more in Cosmos: ISS struck by space junk
New low-Earth orbit satellites must prove they can be safely burnt up in the Earth’s atmosphere within 5 years of the end of their useful life. Meanwhile, companies are racing to find ways to haul more than 2800 defunct satellites out of danger.
However, they are just the tip of the iceberg. There are tens of thousands of deadly fragments that pose an even greater risk.
“The European Space Agency is currently paying 100 million euros to remove just one item of space junk. That’s the value they put on the job,” says Box. “Imagine the value of being able to remove hundreds.”
Every fragment is capable of creating thousands more with each collision. And some desirable orbits are already being turned into high-speed metallic shoals.
“Cleaning these up is not just a desirable thing. I think that it’s going to become necessary,” says Box. “Otherwise, we’re putting human lives at risk.”
Orbital whale shark
Paladin’s reusable orbital garbage collector is designed to be capable of “swallowing” a bellyful of debris in a single mission, offloading the unwanted cargo, and returning to the job.
But it has no “teeth”.
“Our design doesn’t pose a threat to active satellites,” says Box, who is part of the University of South Australia’s Venture Catalyst Space program. “It can’t be misused as a weapon. We can only scoop up fragments and other small items.”
There’s no net, grappling arms or harpoons.
“Our bespoke technology is in the debris funnel system, the container system and the contents management process,” he explains.
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Up front will be an armoured collection scoop. Everything else will be positioned behind it, with even the solar arrays folding behind it to avoid becoming debris themselves.
Once it opens its “mouth”, momentum will direct the debris into a lightweight container.
And it’s this “stomach” that represents Paladin Space’s greatest breakthrough.
“You don’t want it just to float out again. We’d hate for that to happen,” says Box. “The container is ingeniously simple in a way, but needs some very clever technology to work.”
It sounds simple, but in space, absolutely nothing is easy.
Garbage guts
The junk collector will also photograph each object for study before bundling them away for disposal.
NASA research suggests most will be splinters – needle-like shards shredded out of a satellite’s structure by the zero-gravity explosion – but they’re not sure.
“At the moment, we have very little understanding about what these shapes will be,” says Box. “And that’s of great interest because, if we can figure it out, we may understand why these satellites keep breaking up”.
Once full, the disposable – and replaceable – container can be sent towards a fiery demise in the Earth’s atmosphere. Or delivered to an orbital recycling foundry.
“We want to see if we can leverage the metal-powered thruster technology used by Neumann Space,” Box adds. “We can see a path towards replenishing our fuel source from the metal we catch. That could be a fantastic way to ensure the mission keeps going”.