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Science

Space debris and the price of being a pioneer

Scientists will tell you, "Space debris is an urgent issue. We've got novel technology to deal with it. But we can't get the funding." It's a lot like climate change. But do we really want to wait until it's too late?

Pioneers carry a heavy burden. Everything is new and you're the first to try them out. If you fail, it's moon dust on your face. And those who follow will follow you with the benefit of being able to learn from your mistakes.

Fortunately, the global space debris community is stacked with pioneers. Everyone is in the same boat … Or, if you prefer, perched on the same derelict satellite.

The community knows and says the threat of space debris is real and "urgent," a word frequently misused like "love," but in this case is true. And yet there are differences of opinion. Less than a third of the thousands of satellites we have launched since the start of international space exploration are still operational. The rest linger like zombies. If they collide with one another, they create a cascade effect, spurting storms of yet more junk above our skies. Some of it falls to Earth and when we're lucky it burns up in the atmosphere. And some of it poses a risk to global communications and Earth observation satellites - in extreme cases, possibly even those other pioneers in space - astronauts on the International Space Station.

The problem is those in the community are struggling to convince people "outside the room" that the problem is urgent.

"Why? We're humans. It's the same story as with climate change. Until you're hit personally, you don't believe it," says Luisa Innocenti, who heads ESA's Clean Space program.

Ignorance is no defense

We, the public, just don't see space debris - in the very real sense of seeing - as a problem. Decision makers, concedes Innocenti, may also think they have more pressing issues to deal with. Even scientists took a while to get on board, she says. Which is strange, because we've had a number of near-misses.

"Twenty-five, 50, 100 meters - these are very close approaches when the relative velocities are 10 kilometers per second," says Darren McKnight of engineering and software firm, Integrity Applications Incorporated in the US. "So if you're not watching the number of these close approaches - which nobody is - you can say, 'I didn't know,' but if we monitor these events, we can act responsibly."

Active space debris removal is complex work, and largely unchartered territory, so there's a good chance we don't even know how complex it is. The Japanese space agency JAXA recently trialed its KITE technology, using a tether to pull junk out of orbit, but failed.

KITE - Kounotori Integrated Tether Experiment (JAXA)

JAXA's KITE capture technology uses an electrodynamic tether - but it failed in space

Apart from KITE, nothing has been tested in-situ. 

High price for pioneers

"We don't know how to do it, nobody knows how to do it," says Innocenti. "There are issues of responsibility - you don't want to mess it up and create more debris in the process."

And it costs money. Lots of it.

"Particularly the first mission will be costly. It can be difficult to motivate decision-makers to pay a high amount of money to remove just one piece of debris," she says.

But ESA hopes to be the first to remove a significant threat with its e.Deorbit program. To avoid any foreseeable legal issues, which would add an irritating layer of complexity, ESA is targeting a piece of its own junk, possibly the environmental satellite, ENVISAT. It's been "dead" since contact was lost in 2012. Contrary to newer satellites, ENVISAT was launched without a built-in deorbiting solution.

Race of competing technologies

ESA is focusing on two technologies for targeting and capturing space debris, a net and a robotic arm. But there are others. The Surrey Space Centre in the UK, for instance, is testing a net and a harpoon.

"The net works just like a fisher net on Earth. It wraps around the target and with that you could potentially drag it down to ground," says Jason Forshaw, a research fellow at the centre. "And the harpoon has barbs. It's fired at the target and the barbs stop it from being pulled out. Using that you can drag the target down to Earth so it can burn up." 

It's estimated that removing space debris will save money in the long-run, especially for companies running expensive satellite constellations. But some of these capture technologies could present future commercial applications too. For profit.

"The real advantage of a robotic arm is that you can use it for on-orbit servicing. You could change a battery or refuel a satellite to extend the life of the mission," says Innocenti. "So we can reuse the arm for other markets, and nets could be used for asteroid mining."

Responsive and cost-effective

It is clear that active space debris removal will cost money. But there is a good prospect of making money, too, through spin-offs from the technology. At the very least space companies and agencies will save money over time as they reduce the threat to active missions. But there's still no consensus on when we should start the hard work.

ESA Pressebilder - Müll im Weltraum (ESA–David Ducros, 2016)

The space debris community is focusing most research on a few capture techniques, including nets like fisher nets

"Everyone agrees that active debris removal is necessary, but they don't have agreement on the urgency - when they should get started," says McKnight. "It's like Y2K. We didn't wait until January 1, we started way before. It wasn't an issue because we started before."

McKnight goes beyond the debate over the best capture technologies. He says if we monitor the threat more closely, we should be able to respond to real, imminent threats within a five-to-ten day window.

"This might be more expensive, but to get one mission to prevent one collision is much better than the current approach of removing objects without knowing whether they will collide," says McKnight. "The way the math works is that it takes 35 to 50 removals to prevent one collision. That's very expensive. So if I can be more responsive, I can be more cost effective."

Wouldn't you just hate to be the financial controller in charge of deciding all of that?

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