How To Clean Up Space Junk

[@sione5754]

what we need is a vacuum in space.... ah crap there is already

[@jazzling]

hahaha this comment gave me aids!

[@dnoodspodu1159]

But the one in _Spaca Balls_ was better

[@RimstarOrg]

Do they win a fuzzy toy if they manage to grab it?

[@THEMATT222]

Their satalite wins exposure to our warm and fuzzy atmosphere

[@chocolate_squiggle]

In 2021, it seems they changed the design to use a net, and haven't done anything yet. The SwissCube1 is still in orbit. This project was turned into a private company and given a contract in 2020 to collect one satellite in 2025. The new contract cost 84 million euros. Hardly seems value for money to remove one item.

[@LedNe0nDevil]

Yikes...

[@ilghiz]

In Russian we pronounce sp[oo]tnik (oo in either moon or cook). It's Russian for fellow traveller and satellite. P[oo]t means path (these words are cognates), p[oo]tnik means traveller, prefix s- means co- or with-.

[@columbus8myhw]

Unless you speak with a Scottish accent, the words "moon" and "cook" actually have different vowel sounds.

[@adamya6540]

So...it's P[oo]tin?

[@randomhuman2595]

Hahha

[@robertmurphy6566]

Thank you! I honestly appreciate it. The US has a reputation for arrogance especially when other languages are concerned. I plan on being an exception.

[@tradetor]

Swiss, you got my respect

[@veritasium]

I asked about this but apparently there are practical as well as diplomatic issues with this. First, it would be tough to get the require precision from the ground, especially for small pieces of space junk. There is a risk of breaking one piece into many. Diplomatically if a country started removing objects from orbit using lasers, it could be seen as a problematically powerful technology.

[@DDryTaste]

"hopefully to start in 2020" was very wishful thinking.

[@alexmueller4047]

Are the swiss the only ones who actually want to do something about this? Really?

[@alexanderhorspool1906]

The main problem is that each cleaning probe and its launch vehicle are amazingly expensive, and no matter what they tell you, space junk in LEO does not remain up there forever, there is still an exceptionally thin part of the atmosphere called the exosphere, which will make sure that this space junk does not stay up there forever. It is still a problem though obviously, just it's not as bad or as permanent as catalst is telling you. (Could still kill astronauts)

[@drjwilber]

probably

[@janrepp6562]

Esa just announced a big scale mission

[@oerlikon20mm29]

of course not, but you gotta remember Switzerland has the highest GDP of any country and are most likely in the best financial position to do this... also its 2021 and the project is not underway as of now according to my knowledge, their government must have judged it to be too expensive for the potential gain as well

[@exceldonkey]

WALL-E

[@salehal-mazrooei7996]

Call WALL-E he will get the job done.

[@veritasium]

the only way it could not burn up entirely would be if it were huge. I don't think anyone would try to bring down a gigantic piece of space junk. Plus if they did, they would ensure it landed in an ocean.

[@Enriconism]

This makes me so proud to be Swiss!! Hope you enjoyed Lausanne Derek! :) [+] |

[@7evenpm]

Crazy how much your production quality has improved

[@Baronstone]

The solution has to include large object capture technology like this as well as a laser that can be fired at smaller debris and give it a push towards the planet. Using both of those methods we can remove dozens of pieces of debris per day.

[@joejava]

Baronstone I totally agree with you on that on what you just said because we really need to do something about this huge challenging problem that us humans have caused for our future endeavors. Like what it says about in this video here kzbin.info/www/bejne/a2GUd3iwl6dkgKs I seriously am very doubtful that we could deal with this huge challenging mess that we caused but it's only going to get a hell of a lot worser because each time an object collides it only creates more space debris they're only smaller the breeze even if it's the size of a grain of sand that could still kill you and penetrate anything think of it this way you know how you can use a sandblaster to clean off rust on a metal part this is pretty much what it would do to you in Space by the time you go to pass through it it would destroy you before you even got past it. Thank about it, It's food for thought really!..

[@sidd0405]

0:19 SOUND IN SPACE! That's amazing .

[@monsieurbernoulli8101]

I didn't know you could have a french AND a german accent

[@stefansauvageonwhat-a-twis1369]

Monsieur Bernoulli nein ach c’est très très simple ze le fayire! Ja ja!

[@santoshp7887]

Can you update on this

[@matszz]

This is how the Borg are born. The cube, the assimilation, we're all doomed.

[@AbuserTube]

+matszz Resistance is futile :-)

[@ahgflyguy]

I'm in this field. The thrusting technology is being worked on else-where. The solution they chose looks pretty decent. The rendezvous and relative navigation problem they didn't mention much about, but their solution is not outlandish for what they aim to achieve. The grappling technology is what they appear to be working on, and that is great. This seems decent for what it is trying to do.

[@playerthree38]

"This is built to succeed." lol. only the Swiss. love 'em.

[@tutentDotCom]

I've been wondering when they would get around to going from monitoring junk to actually cleaning it up. Nice to know someone else is thinking about it and has the ability to do something about it.

[@plpredictions]

reminds me of gravity the film!

[@WaKandaIRE]

That debris going clean through the guys head

[@Vector_Ze]

Why? Gravity was absurdly unrealistic. I'm a science fiction fan. Gravity was an embarrasement.

[@mr.j_krr_80]

@@Vector_Ze but it clearly delivers the message.

[@nolanwestrich2602]

@@Vector_Ze Yeah, but it was a lot more realistic than, say, Star Wars.

[@TheGuyWithTheFace1]

your videos are getting a lot better keep up the good work

[@mollusckscramp4124]

"Hopefully starting in 2020..." Oh man, you guys were so overly optimistic lol

[@thecuriousengineer]

"If we don't do anything space will become soon inaccessible" Its a strong and serious message.

[@stamas999]

swiss, you da real mvp

[@AuthorityQuestion]

Time well spent Swiss and interesting too.

[@gaberielpendragon]

Veritasium Couldn't this same principle be used to simply decelerate the debris so it falls into orbit instead of needing to keep sending up satellites to grab one piece at a time, in theory making it significantly more cost effective.

[@spress15]

Cool! Great to see that something is being done now! Thanks to the Swiss - we should follow their example.

[@potongbebekangsa]

ive always wondered how space shuttles and the ISS could evade all that space junk orbiting the earth at high velocity. it cant be just pure luck right?

[@dnrob7]

The don't need to. The ISS is at a very low orbit. They encounter residual atmosphere all the time that slows them down over time so they have to use boosters periodically to correct their orbit. This minor air resistance is what keeps them quite safe as satellites are almost always put into higher orbits as they can't carry the fuel to correct orbital decay. Any junk that crosses low enough to ever hit the ISS is already destined to fall back to earth and is very unlikely to stay in orbit long enough to land that 1 : 1 billion chance to hit.

[@lewisnorth1188]

Dan Rob is wrong, the ISS does encounter debris and sometimes has to adjust its orbit to avoid debris. The modules are also protected be kevlar in case something does hit them.

[@tonycraft7819]

its because the earth's flat, dummy

[@byamboy]

it's because: we and everything we produce here on earth are tiny!!! :-D

[@PTNLemay]

YES! Damn that show is under-appreciated.

[@ThunderTurtle7]

Individually picking up each piece seems like a terrible idea.

[@diceman199]

It would certainly give them a push in the right direction. The question is what would be the effects from the vaporized parts. Obviously it would solidify again but would it clump? Would the small fragments pose a risk. You'd probably end up with many times more pieces, though much smaller, so I don't know if the end result of that method would be beneficial or not. Could be worth a small scale trial though

[@HappyBeezerStudios]

Wouldn't it me more efficient if the space janitor youd be reused? Like grabbing one part of depries and flying into a crash orbit, then releasing it and move on to get the next piece of junk.

[@thenukedgamer65]

it would have 2 enter the earths gravity feild or propell it into earths gravity.

[@HappyBeezerStudios]

I tried that stuff in Kerbal Space Program and the only problem was my fuel. So the cleaning sattelite has to go into extreme eliptical orbits for every piece of junk to remove.

[@thenukedgamer65]

HappyBeezerStudios welll seeing as were not going 2 go 2 pluto ect anytime soon,solar energy would work.we got about 50-100 years before humans can do anything super big space wise.time is on our side for once

[@JohnSmith-vn7vk]

+HappyBeezerStudios if you can catch something that's faster than a bullet without damaging yourself / your equipment, why not!

[@HappyBeezerStudios]

Ofcourse adopt to its orbit first so that you can grab it carefully. There is a reason why Space Shuttles and the russian spacecrafts don't crash into the ISS and shatter it into a cloudy ring orbiting the earth.

[@kurtilein3]

thats true, i dont know if there are international laws, but today almost every mission is planned in such a way that it doesnt produce any space debris. But if things go wrong it still happens. If a sattelite stops working suddenly, or after you send it up you just fail to make contact / its electronics fail to boot, then you still get space debris.

[@CsBence98]

That Swisscube looks similar in size and shape to MaSat-1, doesn't it?

[@argh523]

CsBence98 It's a cube-sat, and they're all the same size because when they started to let universities hitch a ride on rockets for very small and ultra cheap projects, people realized it would make everyones job a lot easier if the little buggers are all the same size and behaved the same way. Rocket manufactures now have standardized launch systems for them, and they fill up spare payload weight by letting people deploy cubesats very cheaply or even for free in some cases.

[@JohnIsUber247]

Its a step forward to something that could solve the problem as a whole. Its not so much the kid throwing the pice away then walking off. Its as if the kid goes, invents a remote-controlled dump truck toy, THEN uses that to throw his piece of trash away. Its not the act that is important. It is what is created in the process. This satellite (If it works) Then can be produced on a larger scale and used by any country to clean up their trash. Switzerland is innovative, not annoying.

[@Tac-0]

"you cant have swiss junk flying around in space" i giggled...... xD

[@omb1987]

by letting the object slowly catch up with you. so that the actual "speeding towards you" is less then a meter per second. you just bring yourself (or in this case the cube) into the same orbit but ahead of the object so that you move slightly slower then the object and let it catch up with you. or do the other way round and catch up with the object.

[@headrockbeats]

But... but... if just one of these janitors happens to accidentally collide with anything up there... then it would make more new debris than thousands of such janitors could clean up.

[@aakksshhaayy]

the janitors only plan to clean up the large debris (big ball size) if janitors break apart, they would create only small debris. Suffice to say, with half a million particles of small debris, it is not possible to make an impact in cleaning it using this janitor type of approach. We will have to use a large scale collector satellite in the future to capture many particles at once.

[@CMDrRedstone]

humans are pretty good with netting fish and making them extinct, why not do this here xd

[@SillyPutty125]

It's a proof of principle. If this project is successful it paves the way for more ambitious tasks in the future. Starting with a specific target in mind makes a lot more sense then, "we'll just launch it up there and have it grab the first thing it sees." I'm not an expert on space propulsion systems, so I'll give them the benefit of the doubt that this project is a reasonable first step.

[@tahirmehdi]

Planetes anyone?

[@luke666808g]

yeah i like that show

[@henrysondaveong]

This is like watching a documentary show. Very nice. Great Job! Loving the videos.

[@thomasrad6296]

The amount of mathematics, time, energy needed to preform such an easy task does not seem worth it. I think that there needs to be a solution but this really does not seem to be very efficient or practical.

[@argh523]

Thomas rad It might not seem that way, but this is actually the most practical and efficient idea anyone has come up with, at least for part of the problem. Those satellites are quite cheap, and you launch them more or less for free, because they can hitch a ride on rockets with some kilograms of payload left. And no, it is not an easy task at all. To get rid of junk in space, you have to rendezvous with it somehow. Hitting something is comparitavly easy, going somewhere without beeing a couple of kilometers per second to fast is a lot harder. On the question of whether is it worth the effort, yes, we do need to clean up sooner or later. The problem is, with every collision, you get thousands of new pieces, and there is a potential for a chain reaction which will destroy pretty much everything in orbit. Nowdays, new satellites are either shot into low orbits that will naturally decay within a few decades at most, or the satellites have propulsion systems for the sole purpuse of crashing them into earth or moving them to junk orbits. But there are still many old objects left, and there will be new ones created because things malfuction or on missions where litering can't be avoided.

[@TheObsidianAsh]

Exactly.

[@charlidog2]

I have to thank you. You've made my week, maybe month. That you think my ideas might warrant or that I am in any way competent to even attend an event like that, let alone participate is extremely flattering. Losing a spacecraft for every piece of junk sounds inefficient to me too. Solar cells and autonomous flight sound right, maybe a way to jettison the piece towards earth once captured. That process could be used for propulsion towards the next piece.

[@TheThunderSpirit]

this idea is very poor.. must come up with something smarter than pick up space junk one by one like that. what is it gonna do after it picks it up? throw it towards earth?

[@frankietheiling9308]

throw it towards earth's atmosphere where it will burn up, did you not hear the old man?

[@TheThunderSpirit]

no young fart didn't hear that.

[@trendhouse6799]

It's gonna decelerate and deorbit along with the captured satellite. They'll both burn up. Yeah, not a very efficient way indeed.

[@snowtime5500]

Very efficient if you send thousands at a time. There isn't much options here.

[@jsfbr]

It does sound ineffective, but no other "swooping", "by the bushel" solution has been aired so far. In my view, worldwide initiatives are almost nonexistent, and we're already very late in this very important endeavor. At least the Swiss are thinking about it...

[@PinkChucky15]

I knew there was a lot of junk up there orbiting Earth but I never knew it was so bad. The Swiss are pretty awesome :-)

[@MVHiltunen]

The by far most practical (and the only practical that comes to my mind) way of cleaning up space junk is by vaporizing it with lasers. Preferably by spaceborne lasers that operate on frequencies that are absorbed by the atmosphere, so that they cannot serve as weapons if pointed towards ground. For very large individual pieces this kind of physical tractoring would be a good idea.

[@thegreatgodkirby]

Hey Derek, love the channel. I have a physics question for you. Atoms are made of protons and electrons, protons being positive and electrons being negative, and the atom stays together because of the attraction between the two charges. But if that's the case, what keeps the atom from collapsing into itself? I know that electrons do not 'orbit' a nucleus as we may think but rather appear in an electron cloud, but the question remains. What force keeps the electrons from collapsing into nucleus?

[@panchor]

I hope you found your answer 9 years later.

[@llloyd4]

Agreed, that is my idea, like a space born 'snow plow' that makes a series of overlapping orbits that eventually cover the entire planet, with a plow big enough and thick enough to take the impacts, and ping the objects into a shallow spiraling decent so it has lots of time to burn up.

[@bobbyhill6374]

i think having a ring that is large enough for the biggest objects to be able to pass the it, step 2 have a self healing material be a net with the openings small enough where the small object cant pass though it. objects can rip though the the material there by slowing the object and the net will heal over time. on the ring can have solar panels to provide energy to keep it in a stable orbit. this will allow us to slow objects so they will naturaly fall back to earth, and this only have to be done once. i think having 2 or more will speed up the progress of removing the space junk

[@tapir78]

As "a Swiss", I can only agree. Thank you, your comment is totally correct. Apart from engineering we "Swiss" do food supply business, commodities trading, pharmaceutical stuff, and banking as well. Damn. I wish it was just engineering :-)

[@The_stone_Philosopher]

thanks, I often do a lot of the answering but I'm glad someones there to return the favor :)

[@ReasonMakes]

I think the main problem with that idea is the acceleration (the best way to get something on a collision course with Earth is to accelerate in the opposite direction of your orbit). Small propulsion systems are too slow to accelerate an object without dooming itself. Large propulsion systems are very costly on fuel. I hope we can develop what you're describing someday, but for now this is a smart choice I think :)

[@satoau1]

i thought a lot about this back when the story came out, and really we don't need to capture space junk, just give it a very slight nudge so that its orbit drops and it burns up in the atmosphere. for that something like a 1-degree flying wedge satellite would do, kind of like a bulldozer. the tiny impact angle would offset the huge speed, and the bulldozer would stay up there.

[@JVIPER88]

Maybe, but at the same time, a small adjustment in thrust can lead to a large change over a significant enough amount of time. Obviously, its not going to be as efficient as a vacuum cleaner sucking up dirt in your living room. It will take a LOOOONG time to gather up even a fraction of what's floating around us up there.

[@jedyobidan]

i'm fairly certain destruction in collision is based on loss of kinetic energy of the two objects. which means we should be calculating it based on KE rather than momentum: KE = 1/2mv^2 0.5(CarMass)(CarVelocity)^2 = 0.5(DebrisMass)(DebrisVelocity)^2 DebrisMass = (CarMass)(CarVelocity)^2/(DebrisVelocity)^2 DebrisMass = 0.031kg, or about 31g Which seems reasonable enough.

[@Person1873]

hi 1Veritasium, i do love these segments you've been doing for catalyst, however i was wondering if you had time to continue to make your older style video's? e.g the debunking of scientific misconceptions.. i can understand if you're too busy but i would like to see a little more of your older style content, thanks :)

[@krytek2361]

Excellent. Thanks Derek!

[@SomeHobo147]

The swiss are awesome

[@joel5372]

Btw, what is exactly location on min 2:14 ? Thanks...

[@bunny10841]

cannot believe that I am actually about to work on this project. In 2012, i just finished my bachelors

[@1v966]

Wow, that’s so cool. The guy in the vid talks about the project going fully functional “by at least year 2020”, how’s it kicking?

[@bunny10841]

@@1v966 that specific mission is dropped and there is a similar mission with European Space Agency already started

[@lukaspihl]

I would think so too, my guess is that it's too hard to make at the moment or surely that would be a better solution.

[@t3tsuyaguy1]

Proof of concept. No ones done anything like it before. Once they can prove this is possible. Then they can work on a design, which is capable of redirecting to another target or more, before re-entering the atmosphere itself. Please consider the concern of just swapping one piece of space junk for another, and the exponential increase in energy cost as you increase weight. Fuel weighs a lot. It may genuinely be cheaper to handle one piece at a time.

[@sir_Mauser]

Nice idea from Switzerland! I noticed that no Internet Junk are around to dislike this video :)

[@kurtilein3]

Yes, actually i agree with you. Whats really trending is what i call the superlow earth orbit, so low that its scraping the upper layers of the atmosphere. So the orbit will degenerate after years or decades unless there is propulsion to counteract it. (it can be tuned to mission requirements). The problem is that the trajectory of the individual rocket puts huge restraints on what orbits can be reached by any payload. And the junk removal sattelites will need orbits a bit higher than the ISS.

[@MrJero85]

I think this project is more along the lines of proof of concept then a massive scaled up operation. I'm not an economist but as far as I can tell: yes, scaling up almost always tends to lower costs over the long term.

[@garryyL]

I was going to ask that.. not the new orbit part, because you would want to slow them down so that they fall out of orbit.. but that's just a technicality; otherwise, I think you're right. I feel like if you could find a way to slow down the debris to accelerate the janitor, it would be much more effective as well.

[@diceman199]

Light pressure is very low. I don't know if anybody has done the calculations but I suspect we'd end up with molten lumps before we were able to push an object significantly...so it might make it worse. Worth running some calculations though

[@flekken88]

What happens with the junk when it burns up in the atmosphere? Is it like burning junk on the ground with fire or something else happens with it? What happens with the waste after it burned up? Is it falls back to earth or only gases created and stays in the atmosphere?

[@Rey513]

Not a bad idea! At first blush, the problem I see with that is it's actually pretty cold in space, so it might take a while to melt... on the other hand, the pressure is extremely low, so maybe it would sublimate! Anyway, it seems the trick would be making it last long enough to actually make the collision without sticking around long enough to become its own problem.

[@blade00362]

Satellites are always put up with the help of the rotation of planet earth. So first of all you try to get the exact same orbit of your target, then you just accelerate towards it decelerate when close enough. Launching a mission using a counter clockwise orbit, targeting something that is on a clockwise orbit would be inefficient but doable if the altitude is high enough. Satellites use an RCS to tweak their path if it's a little off or even deorbit it if it's broken or obsolete.

[@Galakyllz]

This was an excellent video. Nice job.

[@riseandshine4885]

Even after 10 years problem remains the same.

[@toxicgamesorg]

swiss are space janitors nice!

[@The5krillex]

Cool how many ksp-players searched how to get rid of debris xD Proud of switzerland to do that in real live (:

[@TjayLifts]

exactly, the problem is at its early stages so doing this will result in no more space junk from this point forward. They are able to plan launches in ways to avoid space junk at the time so really there is no need to clean the space junk up until we find a reasonable solution to the problem; as human technology gets more advanced someone will find a way to get rid of all space junk, but for now all we can really do is stop creating more space junk.

[@Gilroid]

I would recommend some kind of gel that would absorb the impact instead of something solid with the potential of breaking up into more debris.

[@BahamutsKnight]

no, but mass does, especially in orbits closer to the atmosphere where eventually the larger mass would cause the whole thing to begin falling toward the planet

[@tiagotiagot]

Have you tried making somthing heavy on a relatively frictionless setup (like over ice, or hanging on a rope, or on top of a sheet of water/air etc) spin fast? And don't forget we're not talking about making one thing spin in place, but actually two things spin around each other, which involves a bit of translation as well as rotation (or if simplifying the system, rotating a single object with the mass equivalent to the sum of the two objects but distributed heterogeneously).

[@VascoElbrecht]

what about the small derbies? Removing all the big ones will prevent smaller ones be created by collision... but the small ones that are already there a still a problem: Not tracked and quite a lot of them. Any plans to capture those? could you use magnets to capture these?

[@heynando]

slap in the face with words: - Those games are frustrating. - They are built to be frustrating. - And what about this?! - This is built to succeed.

[@sir_Mauser]

Swiss thinking --> 5 debree per year American thinking --> making 5000 debree per year and keep them there. I prefer the Swiss thinking after all.

[@TheTrueRandomness]

Satellites are expensive because they are incredibly reserach-heavy one-off items. Given that the janitor is tiny and can probably be adapted to other debris simply by using different software/different trajectories, it might be possible to actually get some economy of scale if they build and launch a couple of these each year.

[@poo2thegeek]

If we can use lasers to slowly increase speed, then could we not reach huge speeds (approaching c) by just sending out a ship which uses a similar method as shown above, getting its energy from a micro nuclear reactor or just some solar panels. It could slowly accelerate over many months and, due to spaces lack of drag, easily get to huge speeds and travel interstellarly.

[@Nielsblog]

Perhaps that could work too. And yes, I completely agree with you. All satelites should have a "suicide circuit" that works automatic when it can not longer function properly.

[@GrantRobBradley]

Go Swiss!

[@JohnSF93]

maybe, but the power requirements to get the magnet to work across such great distances would be enormous. and the problem is, you can't make the magnets attract only the debris. If it's powerful enough to attract a significant amount of junk then it's also capable of dragging several functional satellites as well.

[@Cars_and_Robots_]

It can be frustrating at how slowly this process is done, but yet, it is better than nothing :)

[@plore]

Once the debris is being held by the craft, it could burn retrograde just enough where the orbital path was entering the atmosphere which at that point, the debris would be released still on the path that reenters while the craft would then burn to put its orbit back to normal manned or unmanned.

[@xeno-crisis]

Claude Nicollier is kind of my hero since I'm a little kid :) I still have his signed picture :D It's awesome to see him on Veritasium !

[@ahgflyguy]

Considering that the fragments are likely to be made of standard spacecraft materials (ceramics, paints, aluminum, fabric), no, it is unlikely that there's much magnetic material. Ferromagnetic materials are avoided to some degree precisely because of their magnetic interaction with the Earth's magnetic field (and the satellite's own, smaller, magnetic field).

[@charlidog2]

Low earth orbit needs a velocity of 7.8 km/s. A high powered rifle's muzzle velocity is 0.9-1.2 km/s. Doesn't matter what it's made of at those speeds. The key is for the ice to last long enough to hit the junk, and then sublimate (go directly to gas, like dry ice) as quickly as possible.

[@Oafing]

This may sound pretty a bit daft but how about sticking a rocket(ion propulsion or whatever that thing was) onto the cube and then program it to fire every time it is aligned with the earth magnetic field(or something to that effect) slowly but sure putting it off course and into the atmosphere. Then the janitor cube can stay up and continue the process!

[@joel5372]

Waaww..thanks very much bro...someday i must go there... :)

[@keaton1717]

wind chill is wind using convection to cool you off. wind burn is friction from wind and UV exposure

[@jubo90]

that really doesnt sound like the best way to get rid of this problem.But using the atmosphere to burn up the debis is probably a good idea. What we need is some kind of scoop, that changes the orbit of the debris down into the atmosphere, instead of grabbing the objects one by one. Of course, you would need some sort of material that can withstand the impact, or a way to slow it down enough to fall into the atmosphere by itself

[@tejanos2]

What about the burning of the debris? would it harm the atmosphere? or change anything at all?

[@ThomasBaxter]

Absolutely I agree. I've been toying with ideas of aerogel like scoops to pickup small debris. Once it reaches a certain mass, the collector and the debris will proceed to a graveyard orbit, as it is more efficient than deorbiting. The idea only would work for small debris (not large scale satellites or debris where political intrigue plays a part)

[@faneb]

I'm imagining something with a sort of spring-loaded piston, which could fire bits of junk away along a retrograde path, hopefully into a low enough orbit to have atmospheric drag and a decaying orbit. If the cleaning satellite had a large mass relative to the junk, there might not be too much extra velocity to deal with. Maybe it could even use the firing to adjust its orbit to intercept the next piece of junk.

[@plore]

Just giving the debris a push retrograde would only slightly affect its orbit and grabbing the debris and slowing itself down so the debris would enter the atmosphere would mean that it would then have to burn more fuel to but itself back in orbit each time.