Space Garbage Truck Passes its First Test

Back in April we reported on the successful launch of the SpaceX Falcon 9 rocket to the International Space Station which carried, along with supplies and experiments for the orbiting outpost, the RemoveDEBRIS spacecraft. Developed by the University of Surrey, RemoveDEBRIS was designed as the world’s first practical demonstration of what’s known as Active Debris Removal (ADR) technology. It included not only a number of different technologies for ensnaring nearby objects, it even brought along deployable targets to use them on.

Orbital debris (often referred to simply as “space junk”) is a serious threat to all space-faring nations, and has become even more pressing of a concern as the cost of orbital launches have dropped precipitously over the last few years, accelerating number and frequency of new objects entering orbit. The results of these first of their kind tests have therefore been hotly anticipated, as the technology to actively remove debris from Low Earth orbit (LEO) is seen by many in the industry to be a key element of expanding access to space for commercial purposes.

Six months after its arrival in space we’ve now starting to see the first results of the groundbreaking tests performed by the RemoveDEBRIS spacecraft, and so far it’s very promising.

Everything’s Harder in Space

To test debris removal technology, you need some “debris” to target. To that end, RemoveDEBRIS deployed a CubeSat target and allowed it to drift approximately seven meters away. Once the target had moved to the prescribed distance, a net developed by Airbus was fired at it. When the center of the net struck the CubeSat, weights along its edges wrapped around the target, completely ensnaring it.

While arguably an ancient technology, even the simple act of throwing a net becomes infinitely more difficult when you’re 300 km above the Earth’s surface. Director of the Surrey Space Center, Professor Guglielmo Aglietti, said: “While it might sound like a simple idea, the complexity of using a net in space to capture a piece of debris took many years of planning, engineering and coordination between the Surrey Space Centre, Airbus and our partners – but there is more work to be done. These are very exciting times for us all.”

One Small Step of a Longer Journey

Some of the larger objects NASA is tracking in orbit

Capturing a free-flying object with a net launched from a spacecraft is a neat trick to be sure, and like the upcoming Japanese demonstration of space elevator technology, is a historic first. But it’s only one part of addressing the space junk epidemic in LEO. What do you do with the target once you’ve caught it?

Soon RemoveDEBRIS will demonstrate technologies for pulling an ensnared object out of orbit, such as a drag sail. This lightweight expandable structure can be attached to the captured object, greatly increasing the atmospheric drag acting on it. As the additional drag lowers the object’s speed, its orbit will decay much more rapidly than it would normally in the thin upper atmosphere.

The University of Surrey hasn’t solved the problem of space junk just yet, but this early success is still something to be excited about. Especially for those who’ve had first hand experience with the danger it poses our spacecraft and astronauts.

“It’s great to see the net deployed and trying out various ways to triage the situation” says NASA’s Michael Interbartolo, former member of the Space Shuttle’s Guidance, Navigation, and Control (GNC) Flight Control team. “Anything we can do to remove that debris, from tools lost during a space walk or bolts from a separation stage or a breakup of a long dead satellite, the safer things will be for the Space Station, astronauts or other spacecraft.”

54 thoughts on “Space Garbage Truck Passes its First Test

        1. Those would be Planet’s Dove cubesats, which are usually launched in large clusters. They don’t have propulsion, so they all stay in the same orbital plane, but they can use controlled drag to space themselves out along that orbit.

    1. Yeah… I’m not buying it.

      This thing is being presented like it’s meant to be a solution to the space junk problem. How could it be though? Sure, looking at that little web graphic makes it appear that the pieces are almost on top of each other but that’s only because all of Earth orbit is being shrunk into mere inches. In reality even if one of these can grab more than one piece of junk it would have to have a lot of fuel just to get from the first to the second! There’s no way they could even make a dent in the whole problem.

      I think what this is is a way to practice removing specific targeted objects. It could be a junk item that happens to be in a particularly dangerous orbit (like one that passes near the ISS) or maybe it’s to remove old spy satellites so that the ‘enemy’ doesn’t steal their tech. Or maybe it’s to remove the enemy’s still working satellite! But it’s not to effect any kind of overall cleanup. To do that would be like showing up to provide flood relief with a bucket.

      1. “I think what this is is a way to practice removing specific targeted objects.”

        Yeah, it is. The little web graphic isn’t really the “space junk problem.” Paint flecks, bolts, etc. aren’t really a huge problem. They’re a risk, sure (space debris constituted *half* the Shuttle’s risk), but the *big* problem are the few defunct satellites in long-lived important (read: sun-synchronous) near Earth orbits – with the main culprit being ESA’s Envisat.

        It is not a coincidence that RemoveDEBRIS is an ESA project: it’s part of the e.Deorbit plan, which is targeted at removing Envisat.

        1. You are exactly wrong about the risks. Large satellites are easy to locate, track, and avoid; and relatively low in number. A small bolt isn’t easy to locate, at 19000m/h closing speed has enough kinetic energy to destroy a spacecraft; and in doing so could create a large number of other small hard-to-find objects.

          1. That’s exactly the problem with leaving the large, dead satellites up there — sooner or later, a bolt or something will turn them into thousands of untrackably small pieces of debris. By removing them while they’re still in one piece, we keep the problem from growing. And unlike the small pieces, there are few enough large, defunct satellites in LEO that cleaning them up is a tractable problem.

    2. That’s exactly what the point is. RemoveDEBRIS is demonstrating technology for targeting and capturing free-flying debris so they can be de-orbited. Hitting it with the net and getting it tumbling will already speed up its orbital decay, but adding a deployable sail to the net would be the one-two punch that pulls objects back down to Earth.

        1. Yes, that puzzles me too. There is https://en.wikipedia.org/wiki/Frame-dragging which would increase drag, but I think the effect would be imperceptible with current measurement techniques. More likely is that the net itself would sweep through more atmosphere and provide greater drag. Considering that, it seems like attaching a long tether to the debris might be the lightest way to bring it down, with a solar panel on the end to create a huge charged dipole cloud.

    3. Because whatever mass you use to “nudge” or “push” the debris to a lower orbit must necessarily go into a higher orbit (equal and opposite reactions, and all that.) You can bring more fuel up with you in order to push more things into lower orbits, but that much fuel is heavy and expensive to deliver to space. By tying drag chutes to them, and letting the atmosphere grab them whenever they’re at their orbit’s perigee, the garbage truck doesn’t have to have to use as much fuel for orbital maneuvering.

  1. How much launches with how much precisely targeted nets would be required to clean up let´s say 90% of those debris ?
    I agree this proof of concept is a nice step, but isn´t it much like using a sieve in the Pacific Garbage Patch ?
    Also, we´re not even able to clean up our pollution down there, even if it´s accessible and relatively cheap to do, so which nation would bear the cost of cleaning up the sky from those debris ?
    Would US, the avant-garde of the progressive, free, democratic countries, show the way like it does wonderfully now ?

    1. Actually most of the plastic in the ocean comes from your buddies in Asia who are used to using the land and sea as a dump. The U.S. is a model of self-restraint compared to your friends.

      Good luck getting those Asian producers to clean up their act.

      1. “look, it´s not only us, it´s mostly the others”
        Perfect illustration why the space will never be cleaned, not even talking about the land and oceans.
        Borrowing the planet and the space from the future generations is not getting a blank check, but a responsibility.

        1. Great opportunity to bring up “THE PLANET” again (yawn)… If you live in a western country, especially the EU, it really IS them, not us. Making plastic bags and drinking straws illegal in countries with a >99% recycling rate and a functioning network of water treatment plants, illustrates the “actionistic” approach of “green” policies that try to fix a problem that doesn’t exist – simply because the LOHAS-sheeple feel that “something” needs to be done. Yeah, follow the baaaaaah… it’s at least a nice substitute for a religion.

          1. Yes, unfortunately the EU bureaucrats are that stupid. And the supermarkets step into this game. You can not get any decent, normal plastic bags anymore – which I reused some dozen times until they are too ripped. But I do not want a bulky “reusable” bag or paper bag which dissolves when moist.

    2. Space debris cleanup using techniques like this are merely a PR event. Launching thousands of dedicated missions with all the steps involved–not to mention the insanity of firing projectiles at tumbling objects in LEO to capture them–all of this would not only be outrageously complex and risky and expensive, it would also create more debris.

      And no, they can’t just release them from the ISS with a can of keyboard duster to go forth, seek, and destroy. It needs to precisely match velocity with its target, which means a full launch vehicle for almost every individual target. This test launched the target and the garbage collector from the same orbiting body, so it’s skipping a lot of the process. I get that it’s only a proof of concept for the net mechanism, but still–I guarantee that ends up breaking large debris into clouds of diffuse hypersonic shrapnel someday. Well not really, because this will certainly not be performed at scale.

      Naysaying aside, it’s extremely cool that they pulled off what they did, and it’ll probably have applications somewhere. That’s the real ROI on space exploration: the spin-offs.

      1. “Space debris cleanup using techniques like this are merely a PR event.”

        No, they aren’t, but you’re right that they’re not thinking about using thousands of them. They’re mainly interested in just a few, and the silly graphic above is really misleading because the giant “cloud” out to GEO is totally not an issue at all. GEO’s just too big, it’s not going to be a problem for a while.

        In fact, the only reason GEO will *ever* be an issue is because it’s not really a 3D volume – the reason you see all the satellites around the equator is because that’s the geostationary orbit, and moving too far away from it completely defeats the purpose of GEO. But it’s still huge.

        The *real* problem is LEO, which is that white halo around Earth. Normally you wouldn’t think this is an issue, because 1) you might not think there are preferred orbital planes in LEO, and 2) you might not think debris lifetime is long in LEO.

        Except there *is* a special LEO orbit, and it’s high enough that debris lifetime is long: sun-synchronous orbits, which are orbits which maintain the same relationship with the Sun throughout the year. And worse, there are specific cases of those orbits which are even more special (dawn/dusk orbits) and special “long-lived” frozen orbits that will maintain the sun-synchronous behavior for a very long time.

        And guess what? There’s a huge dead satellite in one of those special orbits. Envisat. Oh, and who launched Envisat? ESA, the same agency running this program.

        So no, this isn’t PR. This is ESA doing risk management for the possibility that they could be legally liable if a collision happens with Envisat, literally causing billions of dollars of damage.

        Read up on the program this is under (e.Deorbit) and if you read between the lines, you can see this is ESA trying to mitigate the risk while not wanting to acknowledge that they screwed up with Envisat and therefore could be legally liable. ESA’s Space Debris Office’s FAQ page doesn’t mention Envisat once, but all the e.Deorbit mission plans specifically are talking about Envisat, and you’ll notice that the press release ESA put out after the suggestion that they might be legally liable suddenly mentioned “oh… plus we’re studying ways to deorbit stuff!” And lo and behold about 1-2 years later, a symposium on deorbiting stuff shows up, and the whole program kicks into high gear.

        It’s *totally* all about Envisat, but they can’t say that because it means they’re acknowledging that it, specifically, is a risk.

  2. To me, all that energy that was expended to get that junk into space, would be wasted by de-orbiting it. In my mind decelerating it – YES, collecting it all together – YES, then balancing the load and attaching a solid fuel rocket for Trans-lunar injection on a slow journey to be a future source of raw material crashed onto the moon would make better long term sense (now is probably the ideal time with so few man made satellites in orbit around the moon).

      1. I was thinking about it being recycled for use on the moon. Having gravity does help reduce risk when processing liquid metals, there is only one main direction for spills to go. Even ball mills to grind minerals to a dust require gravity. All our industrial scale mineral extraction and purification processes, were developed needing gravity.

        I would never say that anything is impossible, but separating and purifying minerals (safely and efficiently) without a cheap source of gravity would require the creation of a lot of new processes. But there could also be new processing opportunities by having the ability to change the gravitational force inside a centrifugal spacecraft. Forced gravitational separation of constant sized dust particles using 10g to 100g of could be an interesting process. But on the other hand the failure modes of high kinetic energy mineral purification processes in weightless environments would be very bad. I could not imagine cleaning that up.

  3. A net is fine for catching an object that’s moving at a slow relative speed. But that doesn’t describe space junk in general.

    There are millions of objects, each with a unique velocity, with magnitudes of several thousand mph. You can’t catch such objects with any kind of device, without creating many more pieces of space junk.

    1. > moving at a slow relative speed.

      That describes almost every piece of space junk. Orbital mechanics, after all. Increasing the speed you change the orbit, so on every orbit the objects are more or less the same speed, not several thousand mph difference between them.

      1. thoriumber sez: “That describes almost every piece of space junk. ”

        Only true in a two-dimensional universe. Sadly, we have at least one more around these parts. A satellite a 400 km altitude in a sun-synchronous orbit might be coming in north-to-south around 7600 m/s, while the space station is going roughly west-to-east at the same speed, same altitude, but at a closing velocity of 10 km/s.

        Because of differences in inclination and location of the ascending node, it’s most common to have relative velocities between satellites well over 1 km/s, even if they share the same orbital altitude.

    1. Not really? When you first go to stuffin.space, the camera is revolving around the planet at about 1 rpm west-to-east. Everything appears to be going right to left because you’re moving absurdly fast. Once you start manipulating the camera, it stays fixed in space, and you can see objects orbiting (mostly west-to-east, as it should be), and also see the Earth’s slow west-to-east rotation.

  4. Tracking down every scrap large enough to be dangerous would be extremely costly. We could at least insist that the satellites we’re putting up now have independent and automatic de-orbiting mechanisms. For those in LEO, perhaps gas cylinders could inflate mylar balloons that’d exert enough drag to bring them down within a few months. That’d also make them easier to track with radar.

    Is it possible to put up a satellite that would absorb debris without breaking up? It could orbit in a contrary direction to most of the debris, trapping them by absorption. There would be no need to track each one down. It’d be particularly handy for cleaning up the dirtiest orbital paths.

    1. Yep, decades of putting satellites into space with no’er a thought of ‘what when they run out?’ is what has caused the space junk problem. Now everyone has to put up with it – and there’s still no concept of automatic de-orbiting!

      They’ve brought the problem onto themselves.

    1. Yup. Also ITT: People who have no clue about space debris.

      It’s not about removing each and every piece to clean up the orbit. The main goal of most active debris removal missions (such as this one or EPFL’s Cleanspace One) is to remove objects that have a high chance of hitting another object (and thus creating thousands of new debris).

      Think of it as an exponential growth – in worst case, it starts a chain reaction that completely pollutes LEO (Kessler Syndrome, https://en.wikipedia.org/wiki/Kessler_syndrome).
      However, it is estimated that if 5-10 objects are removed a year, the situation can be stabilized. See e.g. the ESA Space Debris Office (https://www.esa.int/Our_Activities/Operations/Space_Debris/Active_debris_removal).

  5. What is the plan to de-orbit the “garbage truck” after it shot its net. How does it avoid being the next piece of junk in orbit? Seems to me this problem of space debris will get resolved once we get a high powered laser or a unit that can focus the sun onto the debris and burn it up. Flying to the debris with a net is just too energy intensive for wide scale use.

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Google+ photo

You are commenting using your Google+ account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s

This site uses Akismet to reduce spam. Learn how your comment data is processed.