Thursday, 02 October 2014
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Researchers propose satellite that cleans up space debris

A proposed satellite designed to clean up space debris could help prevent damage to the hundreds of craft orbiting the Earth.

Researchers at Swiss technology institute EPFL have announced the launch of the CleanSpace One project to build the first in a family of craft that can track down and grab old satellites and pull them back to Earth, reducing the risk of orbital collisions.

Space debris is a growing concern for authorities, as the abandoned satellites, rocket stages and other rubbish around the Earth that threaten to collide with live craft are increasingly breaking into thousands of fragments, which can also cause serious damage.

‘Space agencies are increasingly finding it necessary to take into consideration and prepare for the elimination of the stuff they’re sending into space,’ said EPFL’s Swiss Space Center director Volker Gass.

‘We want to offer and sell a whole family of ready‐made systems, designed as sustainably as possible, that are able to de‐orbit several different kinds of satellites.’

EPFL is already developing an ultra-compact motor to enable the CleanSpace craft to adjust its trajectory after launch so that it can match the orbital plane of its target.

When the target, which will be travelling at 28,000km/h at an altitude of 630–750km, is within range the clean-up satellite will use a gripping mechanism inspired by a plant or animal example to grab hold of the debris.

Finally CleanSpace One will come out of orbit, pulling the target with it through the Earth’s atmosphere where both craft will burn up on re-entry.

NASA is monitoring 16,000 objects larger than 10cm in diameter travelling around the Earth at speeds of several kilometres per second, primarily in low earth orbit — less than 2,000km in altitude.

CleanSpace One will cost around CHF10m (£6.9m) to design, build and launch, and will result in one of Switzerland’s two small ’picosatellites’ being pulled out of orbit.

‘A de-orbiting satellite has never been attempted before,’ EPFL spokesman Michael Mitchell told The Engineer. ‘Our goal is to prove to the scientific and industrial community that the global idea is feasible, of which we are very confident.

‘The very first prototype needs to have a simple design that is sure to work. Once this has been proven, other options — multiple de-orbits, retrieving old satellites back to earth, bigger devices — are sure to follow.’

Who would be willing to pay for clean-up satellites has yet to be determined, but Mitchell stressed that the goal of the project was to prove that it was feasible.

The European Space Agency (ESA) has adopted recommendations that require satellites to be de-orbited after 25 years.

And the rising cost of satellite insurance, which is currently around $20bn (£12.7bn) per craft, could also force satellite operators to act to reduce existing space debris.

But Surrey University’s Dr Vaios Lappas, who is developing sails to drag future satellites out of orbit, told The Engineer that without regulation or a very cost-effective solution, industry would be hesitant to add de-orbiting systems to satellites.

On the topic of technology to pull down existing space debris he said: ‘I don’t think it will happen if it’s on a commercial model. It’s a very interesting engineering and research topic but I don’t see that working unless it is heavily subsidised by big space agencies.’

Dr Hugh Lewis, who is developing space debris simulation models at Southampton University, said there was a growing consensus on the removal of debris and space companies saw it as a potential market.

‘Asking governments to pay for it is one route by which we can get this done but that’s not necessarily the best way,’ he told The Engineer.

Another way to do it is to ask all spacecraft operators to pay into a pot from which you dip into to pay for removal.

‘The other way is through insurance, so that you provide the incentive to remove space junk. If you can reduce the risk to your spacecraft you can pay a lower premium, then it’s worth going up to remove objects that will enable that to happen.’

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Readers' comments (11)

  • So...spend loads of money sending this craft into space for it to just be killed off at the end of bringing down ONE satellite out of the thousands in orbit around the earth and, in doing so, pumping more debris into the space around the earth as they send it up. so in the bigger picture they would be making more rubbish than they would be cleaning up. . . .Can someone please correct me and say that this isnt a really stupid idea. . . .

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  • Why not attach small thrusters to the debris and point the junk toward the sun?
    A push in the right direction with enough thrust to escape earth gravity would be a bit more efficient, plus we would not have space junk raining down on our heads.

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  • Clearly there is a need to clean up near-earth space, that much is obvious; but I would have thought that by now it should be unnecessary to build actually build a craft to prove the concept. Surely we have adequate experience in building launch vehicles and satellites by now that just the grasping/gripping mechanism needs to be proven?
    The more junk you can capture per cleaning mission, the better; so why not consider a very large 'bag' to scoop up the junk. It could be launched folded, and deployed once in orbit. If you use a large 'mouth' to the bag, the need for accuracy in alignment with the junk is reduced.
    As long as the mass of (junk + cleaner craft) isn't too large to burn up on re-entry, you can keep cleaning up (fuel permitting).
    Alternately, you could just simply gather it all up into one single mass and park it in a safe orbit. One item would be easier to keep track off, and avoid!

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  • This is a great idea. Space junk is a really serious problem, especially in the geo-stationary orbit where there are large numbers of live communication and other satellites.

    However cleaning up space is a vastly bigger problem than say cleaning the plastic debris from the world's oceans. Not only is it a lot bigger, but the pieces are travelling in difference directions at speeds which mean it is impractical to just scoop things up without matching the velocity. Newton's Laws tell you that if you hit a piece of junk hard enough - even assuming you capture it - you are likely to send the cleaning craft in to an unstable spin from which it would be difficult to recover. So each piece has to be individually captured in a safe manner. Certainly one craft may be able to capture several pieces before having to re-enter.

    By the way, Anonymous, the energy needed to accelerate any space body enough to escape earth orbit is many times greater than that needed to slow it so that it crashes to earth. If you don't accelerate it enough, it just goes into a higher orbit, and without any guidance system you are quite likely to put it into an elliptical orbit which is far more dangerous! Most small and medium sized pieces will burn up on re-entry with no danger to humans on earth.

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  • Anything that can clean up space debris has got to be a step in the right direction and is long overdue, but it will have to done using great care and precision. Otherwise, one mistake could cause devastating results here on Earth. There are many very important points to take into consideration. Such as timing, and at what point above the Earth will the two satellites enter into the atmosphere. It’s a known fact that a large percentage of the bulk will break-up, but NOT burn-up as they would like us to believe and will survive friction, to impact our planet, so this re-entry point will have to be very accurate indeed. Preferably, to impact uninhabited places like the Pacific and away from aircraft routes. This also raises other questions, such as will conditions allow the released space debris to stay close together and not spread out during its fall? Put JOHN HALL RAISD in your Google slot for more interest.

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  • I like Graham Field's idea best. Don't bother to de-orbit the junk, just collect it together into a single large mass. It's then easy to avoid and no longer a problem.

    The junk collecting vehicle can be reused over and over again, it now only has to nudge the junk into a new orbit.

    Eventually this will create a new moon and its own gravity will be sufficient to collect the junk. In future satellites will be programmed to park themselves on Moonbase Scrapyard. It will then be a rich source of exotic raw materials available for the future in-orbit construction of space missions.

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  • Keep it simple. Use a huge metal orbiting wedge that hits space junk on its angled underside and deflects junk towards the Earth where it will burn up. Along with an ion thruster, each hit will help keep the wedge from falling itself.

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  • It would be far better to build interlocked de orbit engines into new orbiting payloads (if the insurers would tolerate and cover the additional risk). A lot of low earth orbit 'trash' is regularly captured by our atmosphere, but the larger chunks in higher orbits will remain problematic for years. As Robert mentioned above, the orbits are so different it makes it very impractical to 'drag this back to Earth'. Also, I wonder if it’s really practical to launch an orbital craft 'WALL.E trash collector' without adding to the debris, especially if your attempting to retrieve at higher or geostat orbit levels. I don't think anybody has managed to re write the laws of physics with a single stage, earth launched rocket that can achieve a suitable orbit?

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  • At least we don't ned to worry to much about invading aliens - they will see all that junk orbiting our planet and they know there is no intelligent life down there so why bother with the risk of getting hit by it!

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  • Removing any fast moving junk from space without damaging working satellites and then making sure it can be burned up in the upper atmosphere without bits landing in populated areas or damaging an aircraft in flight is a huge technical challenge and is going to be very expensive. One possible way of funding this is to require that any organisation which sends a satellite into orbit must pay for one redundant satellite to be removed from orbit, preferably of similar size.

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