Space junk: Ideas for cleaning up Earth orbit

Jul 12, 2012 By Jenny Winder, Universe Today
Artist’s impression of debris in low earth orbit Credit: ESA

Space may be big — vastly, hugely, mind-bogglingly big — but the space around Earth is beginning to get cluttered with space junk. This poses a threat, not only to other satellites, space stations and missions, but to us here on Earth as well. While we wrestle with environmental issues posed by human activity on our planet, ESA’s new ‘Clean Space’ initiative aims to address the same issues for its missions, making them greener by using more more eco-friendly materials and finding ways to cut down levels of space debris.

Last month ESA and Eurospace organized the Clean Eco-design and Green Technologies Workshop 2012 held in the Netherlands. Clean Space is a major objective of Agenda 2015, the Agency’s upcoming action plan. The aim was outlined by ESA Director General Jean-Jacques Dordain: “If we are convinced that space infrastructure will become more and more essential, then we must transmit the space environment to future generations as we found it, that is, pristine.”

The workshop looked at all aspects of space missions, their total environment impact, from concept development to end of life. The impact of regulations regarding substances such as hydrazine, which is used widely as a propellant in space programs and the development of Green Propulsion with propellants that have a reduced toxicity. Environmental friendliness and sustainability often mean increased efficiency, which ESA hopes will give the industry a competitive advantage, so they are looking at technologies which will consume less energy and produce less waste, therefore cutting costs.

Finally they looked at debris mitigation to minimize the impact to the space environment as well as the debris footprint on Earth using controlled and uncontrolled re-entry events and passive de-orbiting systems along with active de-orbiting and re-orbiting systems. They are even considering tethers or sails to help drag abandoned satellites out of low orbit within 25 years. New ‘design for demise’ concepts hope to prevent chunks of satellites surviving re-entry and hitting the ground intact. Active removal of existing debris is also needed, including robotic missions to repair or de-orbit satellites.

6,000 satellites have been launched during the Space Age; less than 1000 of these are still in operation. The rest are derelict and liable to fragment as leftover fuel or batteries explode. Traveling at around 7.5 km/s, a 2 cm screw has a ‘lethal diameter’ sufficient to take out a satellite. Taking the recent loss of the Envisat satellite as an example, this satellite now poses a considerable threat as . An analysis of space debris at Envisat’s orbit suggests there is a 15% to 30% chance of collision with another piece of junk during the 150 years it is thought Envisat could remain in orbit. The satellite’s complexity and size means even a small piece of debris could cause a “fragmentation event” producing its own population of space garbage. Envisat is also too big to be allowed to drift back into the Earth’s atmosphere. The choices seem to be to raise the satellite to a higher, unused orbit, or guide it back in over the Pacific Ocean.

As ESA Director General Jean-Jacques Dordain says “We will not succeed alone; we will need everyone’s help. The entire space sector has to be with us.”

Find out more about ESA’s Clean Space initiative here

Explore further: Europe launches last resupply ship to space station

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TheDoctor
1.5 / 5 (4) Jul 12, 2012
Hopefully some commercial companies will step up and provide an economical service to remove this debris. I would also suggest that in later decades a mechanism be placed in space were this debris can be directed towards the sun.
El_Nose
2.3 / 5 (3) Jul 12, 2012
that would mean that a company would want to pay to remove space debris -- where is the ecomonic incentive... who would have the money and be willing to pay for it -- in theory most satelittes are USA in origin and should be grounded by the USA
gwrede
3.4 / 5 (5) Jul 12, 2012
I would also suggest that in later decades a mechanism be placed in space were this debris can be directed towards the sun.
Sigh. This really seems to be Rocket Science.

Sending junk to the Sun is about as economical as sending your town's junk to the top of mount McKinley.
TheDoctor
not rated yet Jul 12, 2012
that would mean that a company would want to pay to remove space debris -- where is the ecomonic incentive... who would have the money and be willing to pay for it -- in theory most satelittes are USA in origin and should be grounded by the USA

The way some companies are lowing the cost of space operations, there could be opportunities in the not to distant future for governments for example the USA and also the owners of sattelites to pay a fee for removal.
As far as sending junk to the sun; not feasible today, however in the future, who knows?
GSwift7
2.4 / 5 (5) Jul 12, 2012
As ESA Director General Jean-Jacques Dordain says We will not succeed alone; we will need everyones help. The entire space sector has to be with us.


I wonder if there will ever be a world-wide governing body to regulate space commerce? There really should be some kind of fund set up to handle situations like envisat. If there were something like an insurance fund set up to pay for the disposal of old equipment and cleanup of debris then surely companies like SpaceX would already be bidding for the cleanup work. The cost of cleanup should be included in the cost of launching anything. It would be a real mess trying to get everyone to agree to it though. Agencies with more accidents should pay more, but who decides how much? It would eventually lead to law suits over liability, just like you see with automobile insurance or anything else where a lawyer thinks he can make a buck.
italba
2 / 5 (4) Jul 12, 2012
We can send junk in a black hole, in the future, who knows? Seriously, maybe a cloud of gas could slow down space debris and make them fall back to the earth.
Nydoc
5 / 5 (1) Jul 12, 2012
It would be great if we had satellites that were designed to catch and deorbit other satellites. Like this: http://www.tether...gies.pdf
GSwift7
3.7 / 5 (3) Jul 12, 2012
Another way to help reduce the number of individual objects floating around would be to group satellites together on some kind of central platform. They could share services such as power supply and data storage/transmission and it creates a one-stop point of call for resupply, service and decomissioning missions.

As for the sun, that's a horrible idea. Satellites just need to be built in such a way that they are safe to burn up in the Earth's atmosphere. Design them so that they come apart in a predictable way and use materials that don't rain bits of radioactive poison down on us. I would bet that top secret government spacecraft are already built to ensure they do not survive re-entry, though it wouldn't be 100 percent every time.
Deathclock
2.3 / 5 (3) Jul 12, 2012
There are two approaches that I see, methods that would ground ALL satellites indiscriminately, and methods that would only ground selected satellites... Obviously the former would be easier but less desirable, and the later would be more desirable but much more difficult, as it usually goes...
Eoprime
not rated yet Jul 12, 2012
Another way to help reduce the number of individual objects floating around would be to group satellites together on some kind of central platform. They ...


Like this? :)
http://www.wired....oenix-2/
GSwift7
3 / 5 (2) Jul 12, 2012
It would be great if we had satellites that were designed to catch and deorbit other satellites. Like this


The X-37b might be testing such ideas, among other things. If so, then it's more likely they would use a rigid mechanical arm than a tether though. Tethers are actually tricky to implement with precision. Simply getting a solid attachment to a piece of space junk would be tricky and then there's the issue of elasticity in the tether itself and the center of mass of the junk as well. With an arm you just grab hold and take as long as you like to gently slow down with thrusters. The x-37 (or something like it designed specifically for the task) could do that with enough precision to direct envisat towards the ocean and then break away and safely land itself at Edwards AFB. That way, if you lose your grip on the junk then you just speed back up a little and take another grip. Slow, steady, and precise is the way to go.
GSwift7
3 / 5 (2) Jul 12, 2012
Eoprime:

Like this? :)


yes, very much like that, only commercialized. In my case there would be a sort of landlord company who builds and maintains the platform. It would have docking slots for rent and could allow elimination of redundancies such as power supplies and antenas or even offer the ability for networking between satellites. Then you would be able to service every satellite in the array with one robotic supply ship, much the same as we are now doing with the ISS. It's a simple matter of math really. As long as you could eliminate enough redundancy so that the platform pays for it's own launch weight, then it should be possible to make money. You would only need to make sure you could rent enough slots out to customers.

In the case of GEO, where we already have satellites grouped closely together over population centers, it would make perfect sense.
Sanescience
5 / 5 (2) Jul 12, 2012
If we could get past some political difficulties regarding space weapons, it might work to put up a fempto second laser platform that can slowly impart momentum to objects in space by vaporizing small amounts of material off of their surfaces. Each time an object reaches the point in its orbit when its delta vector points directly at the laser, it hits it with a set of pulses that slows the object a little bit. Depending on the orbits that could be many times each day. And it could target hundreds of objects each day. Over extended period of time the objects would move closer to earth and start to drag in the atmosphere. The nice thing would be that the smaller the object, the more effective it would be at slowing it down.
GSwift7
3 / 5 (2) Jul 12, 2012
Each time an object reaches the point in its orbit when its delta vector points directly at the laser, it hits it with a set of pulses that slows the object a little bit


That's a good idea for small objects, as you said. One problem with that is that it would be somewhat unpredictable. The direction of the change in velocity would depend on the angle of the surface you hit and its relationship to the center of gravity of the object. If you hit a 45 degree angled surface then the resulting vector would be deflected opposite the surface's angle. Hitting the object off center would also result in a deflected force vector. You would also need a VERY coherent beam to have much power at long range, and there's an inverse relationship between power and coherence in a laser. The very powerful lasers you read about at places like the national ignition facility are operated at extremely short range. A laser interferes with itself as the waves lose synchronization over distance.
Sanescience
5 / 5 (1) Jul 12, 2012
True and True.
Most space debris are rapidly rotating as well. Definitely getting individual hits perfectly centered would be impractical. So you average the effect over thousands of hits for each session in a small circle fill pattern. This also helps address a problem of "shading" where the ablated material reduces efficiency. For added effectiveness it might be possible to analyze the long term trend of momentum imparted and adjust target fill shape and timing.

As for coherence and other laser properties I'm not super familiar with the nitty gritty details. I know the military has been looking at laser weapons for a while and there might be quite allot of experience in the communications (laser) industry to address the distances involved.

The one other possible version of this idea is instead use a particle beam of some kind, but that is a far less developed field than lasers.
eachus
2.3 / 5 (3) Jul 12, 2012
Dead satellites are a very valuable resource right where they are. For example they could be collected near a space station to provide protection from solar storms. (Note the near part. If too close secondary particles could increase the radiation risk from a solar flare. But put the junk pile a kilometer or two away, and that is not a problem.)

Of course, reusing some or all of the satellite to make new satellites or space ships is very efficient. Even if you only reuse structural materials, you save lifting that weight into orbit twice.

So how do you gather all this potential debris? We now have plasma engines which have Isps in the thousands. Add a solar array for power, a fuel tank and a grapple, and away you go. A good demonstration project might be moving dead geostationary satellites into a single (slightly higher) orbit.
Sean_W
2.3 / 5 (6) Jul 12, 2012
I keep hearing different things from different sources. Some say space junk deorbits (due to dust and particles and such) in a number of years. Since one would expect that space agencies and companies are being more cautious about producing it now, one would think the amount of debris should decrease naturally. When two objects crash and produce smaller but more numerous bits of junk, shouldn't all of it move down into lower orbits?

And as for pieces that are too big to be allowed to drift back to earth, might I recommend blowing it up into smaller bits? Maybe on New Years Eve or something?
GSwift7
3 / 5 (2) Jul 13, 2012
I know the military has been looking at laser weapons for a while and there might be quite allot of experience in the communications (laser) industry to address the distances involved.

The one other possible version of this idea is instead use a particle beam of some kind, but that is a far less developed field than lasers.


The military lasers are big and heavy, and they have a range from a few miles up to around a hundred miles, not thousands of miles like you would want for clearing space junk. As for communication lasers, those are very low power, so they are able to create a very coherent beam.

There's actually a fundamental limit imposed by nature between the power of a laser and how coherent the beam is. Some of our experimental lasers are near that limit, supposedly.

A particle beam would have recoil, so the gun platform would need propulsion to stay in place, unless you shoot an opposing beam as well.
GSwift7
3 / 5 (2) Jul 13, 2012
To Sean W:

There's a big difference between low orbit and geosynchronous Earth orbit(GEO). Objects in low orbit, like Envisat, will naturally slow down and de-orbit in decades or centuries (~150 years for envisat). For GEO satellites, such as weather, communication and GPS satellites, they are MUCH farther away from Earth so they do not slow down from rubbing on the atmosphere. GEO satellites will stay up there for thousands of years, unless we pull them down. That's not as big a problem as it seems though. Low orbit satellites tend to criss-cross each other (bigger chance of colliding), but GEO satellites are all lined up along the ecliptic and they all move in unison, so they don't collide with each other.

Also keep in mind that space is big. The artist's impression above makes the junk look like a much bigger deal than it is. If they drew it to scale, you couldn't see any of the junk. At scale, even the ISS (the largest thing up there) would be too small to see.
El_Nose
5 / 5 (2) Jul 13, 2012
Why would governments pay for space junk removal if there is no legislative imperative?? Why would anyone pay for space junk removal with no imperative ---

when was the last time a body or government with a lot of money said - hey let's just do the right thing ???

I know of examples of this -- not looking for that -- but normally it takes an accident to highlight the dangers of not doing the right thing.

My guess is that the ISS will crash due to space junk and lives will be lost. Then we will clean it up.

Sad -- but the only way to move Congresses and Parliaments to action.
antialias_physorg
3 / 5 (1) Jul 14, 2012
Seriously, maybe a cloud of gas could slow down space debris and make them fall back to the earth.

You mean what we technically inclined people call 'an atmosphere'? Sorry - space doesn't have that. And putting one up there...well, there's a reason there isn't one.

in theory most satelittes are USA in origin and should be grounded by the USA

The big satellites aren't the problem. It's the tons and tons of debris. And no - the owner's name isn't stamped on each one. So it's really hard to say who is responsible for what bolt floating around out there.

As for lasers evaporating stuff: I think you need to get a grip on the distances involved. Lasers don't stay focused forever.
(And also on the energies you'd need - and what kid of size of laser we'd therefore be talking about. That sucker would need to be HUGE. I'm talking way bigger than the ISS)
italba
2 / 5 (4) Jul 15, 2012
Obviously I don't mean a whole atmosphere in orbit! If we send in orbit some tons of gas, it will expand to a huge cloud and slowly fall to the earth or will be wiped away to the outer space by the solar wind. In the meantime it could slow down debris crossing its orbit.
alfie_null
5 / 5 (1) Jul 15, 2012
Rather than lasers, a bunch of adjustable mirrors; focus sunlight. Vaporize, or whatever.
antialias_physorg
1 / 5 (1) Jul 15, 2012
Obviously I don't mean a whole atmosphere in orbit! If we send in orbit some tons of gas,

Please do the math on that one. Take a trillion tons of gas (a ludicrously large number, you agree?) And see how much that would disperse at the volumes we're talking about here.

Earth atmosphere is about 700km high (with anything beyond 200km being pretty negligible). Our satellites are up to 36000km high (geosynch orbit). Even if you put up as much gas as our entire atmosphere it would be so spread out that the effect would be next to nothing...and it would escape into deep space before it would have time to have any noticeable effect, anyhow.
italba
2 / 5 (4) Jul 15, 2012
Where do I wrote I want to clean all orbits at once? And, for the geostationary orbit, there is no need to clean up! Satellites are in fixed position! Maybe you need to revision your unit conversion math, our atmosphere ends at 70-80 km, NOT 700. International space station is between 300 and 400 km high!
antialias_physorg
5 / 5 (1) Jul 15, 2012
From wikipedia:
Depending on solar activity, satellites can still experience noticeable atmospheric drag at altitudes as high as 700 to 800 km.

The ISS requires regular boosts because it experiences drag from residual atmosphere.

The low orbit stuff is not the problem. That stuff falls back by itself because it experiences some atmospheric drag. It's the mid to high orbit stuff that sits there basically forever clogging up the parking spots for future satellites (most satellites are not in LEO)

Now give me some numbers: how many trillions tons of gas were you planning to get where exactly to get this harebrained scheme of yours going? Be specific. Do the math. You'll discover that you're off by about (at least) 10 orders of magnitude in what we can do today.
italba
2 / 5 (4) Jul 15, 2012
Let's make an example, maybe you'll understand. If you want to erase a pencil sketch, you can do it by dragging once on the paper a big eraser or, more easily, strip by strip with a fine point eraser. Start to see the light? When you want to clean up an orbit, NOT THE WHOLE SKY, just send some gas into it. The debris passing thru this gas will be slowed down enough to not cross anymore the orbit we need. How much gas we need for each "erasure"? It depends on many factors, for instance the mass of the debris. I cannot calculate them, and I doubt it could be done. But, how can you say "harebrained scheme" or "10 order of magnitude"?
antialias_physorg
not rated yet Jul 16, 2012
Start to see the light? When you want to clean up an orbit, NOT THE WHOLE SKY

And how exactly are you going to get the gas there (and have it stay there for any length of time to do any work at all)?
If you put it up using a sattelite/rocket then you probably are inserting more junk than you are getting rid off (not to mention that if you are getting that close with a craft that can carry megatonnes of gas you can do the same thing with a very much smaler craft, an ion engine, and simply pick up the stuff...which in itself is so fantasticaly wasteful/expensive as not to merit any further thought)

Satellites in mid to high orbit aren't big for a reason. Getting big stuff up there is immensely costly. Even getting 1 tonne of highly compressed gas cannister up there would be enormously expensive (and one tonne of gas isn't going to do diddly squat)

I cannot calculate them

So I noticed.
antialias_physorg
1 / 5 (1) Jul 16, 2012
But, how can you say "harebrained scheme" or "10 order of magnitude"?

it's just very simple numbers. Speeds at certain orbits, mass of the debris that is any problem (very small stuff isn't much of a problem, it's the nuts and bolts type of debris (and upward) that is dangerous). From that you can get a momentum. From that you can calculate the momentum you need to impart to get this stuff to a low enough orbit so it will experience atmospheric drag and fall back by itself.

Here's a quick chart:
http://en.wikiped...al_speed

To get something from GEO to LEO you have to impart about 12MJ/kg
on it. That's way more than you'll be doing with a quick spritz of gas.
El_Nose
5 / 5 (1) Jul 16, 2012
Most satellites are in LEO -- its cheap. Do not believe that most satellites are in mid to high orbit that is false.
italba
2 / 5 (4) Jul 16, 2012
With very simple numbers you'll only get very wrong results. How big it will expand each gram of gas? And how much time it will stay in orbit? Days? Months? Years? How much drag it will do on a small debris? And on a bigger one? How many revolutions needs a a debris in a given orbit to cross a gas cloud in another orbit? And what effect will have each cross? If you can find such information on Wikipedia please post the links!
Sanescience
5 / 5 (1) Jul 16, 2012
As for lasers evaporating stuff: I think you need to get a grip on the distances involved. Lasers don't stay focused forever.
(And also on the energies you'd need - and what kid of size of laser we'd therefore be talking about. That sucker would need to be HUGE. I'm talking way bigger than the ISS)


Coherence (both kinds) and focus are certainly challenges. But ultra short laser bursts do not require "huge". Were not talking outright vaporizing of a whole object. Were talking tinny puffs of plasma micrograms (or less) over long periods of time. Even shining a bright light on these objects can change their trajectories through photon pressure, but to deorbit with just the pressure of light might not be on "useful" timescales.
antialias_physorg
1 / 5 (1) Jul 17, 2012
But ultra short laser bursts do not require "huge"

Ultra short laser bursts do also not contain much energy. (Do not confuse power with energy. Energy is power times time). And you need ENERGY not power to vaporize stuff.

The objects we're talking about are nust and bolts size. To slow them down via evaporation you need to hit the right side (if you hit the wrong side you'll speed them up. Just shooting at them willy-nilly will, on average, do nothing).

And no: we don't have the capability of aiming a humongous laser over tens of thousands of kilometers with submillimeter spread AND submillimeter accuracy at something flying at several kilometers per hour.

How big it will expand each gram of gas?

At most an object will fly through your entire cloud of gas once before it disperses (it needs to move relative to it, remember?). So now you've slowed it down by what? A few millimeters per hour? and that at the price of an entire satellite launch. Brilliant.
italba
2.3 / 5 (3) Jul 17, 2012
You continue to spit out numbers without any base. How can you say "an object will fly the cloud once before it disperses"? It's a scientific law? Do you have any proof of it? Experiments? Anyway, for your information, there are two similar projects to clean up space debris using, instead of gas, metal powder (http://www.techno...-junk/). And please STOP with this stupid ranking war!
italba
2.3 / 5 (3) Jul 17, 2012
The last edit cut out the "clean space orbits with water" link: http://dsc.discov...ng.html.
antialias_physorg
not rated yet Jul 17, 2012
How can you say "an object will fly the cloud once before it disperses"?

Because I'm not stupid?

Listen: this is very, very basic stuff: To slow something down via interaction you have to impart momentum from one to the other.
(in your case the bit of debris and the gas).
This means they must be moving at different speeds and/or different directions to one another (i.e. the bit of scrap must move THROUGH the gas). If both are moving at the same speed in the same direction then there will be no impulse transfer (and hence no speed/orbital change) whatsoever.

Now the earliest time your cloud of gas will inetract with the same piece of debris again is after a full orbit. Given that even LEO orbits are on the order of 90 minutes or so - do you have any idea what happens to a puff of gas that sits around in near vacuum for 90 minutes? Hint: it doesn't stay where it is.

(And no, the rankings you are getting aren't by me. I don't do sockpuppets)
italba
2.3 / 5 (3) Jul 17, 2012
Trying to apply the laws of your own word to a very different one is not very intelligent, either. The interactions between a solid object and a very low pressure gas (if you understood I would mean gas will stay at normal pressure maybe YOU think I'm stupid), should be very different than atmospheric pressure ones. Gas molecule will be so sparse that there will be very low interactions, if any, between them. After the passage of the debris you can't expect something like shock waves, interaction between the debris and the gas will be limited to the debris front section or slightly more. The next passage the debris will follow a slightly different orbit, and it will find some fresh gas.
antialias_physorg
not rated yet Jul 18, 2012
Just do the math. Please. How many molecules of gas. Over what kind of a volume. How many passes. Over what kind of timeframe. With what kind of realtive speeds. At what cost of getting the volume/mass of the gas up there.

If you don't see how ludicrous this is I can't really help you. This is jsut so glaringly obvious from physics 101. We don't live in a Sci-fi universe. Stuff on that order of magnitude follows laws we understand pretty well. And you're just ignoring all of physisc with your 'idea'.
italba
2.3 / 5 (3) Jul 18, 2012
If you can make a space debris cross as many gas molecules it would cross in LEO (where, you said it, is not an issue) and keep those gas molecules for a long enough time (years) I see no physic law against it. How much gas in orbit we need? I don't know. Will the gas cloud stay here for some time or it will be washed away immediately by solar wind? I don't know. Will the costs be bearable? I don't know, either. If you think these are "physics 101" information, please find it on wikipedia, as I wrote you before (you keep repeating the same song, so must do I) and I can "do my math". Don't you get bored to repeat always the same stereotyped phrases?
antialias_physorg
not rated yet Jul 18, 2012
If you can make a space debris cross as many gas molecules it would cross in LEO

As I said in my first post: Putting up an amount of gas equivalent to a part of our entire atmosphere is not an option (unless you have a way of getting trillions of tons of gas into orbit). At LEO we have the gas density AROUND THE ENTIRE EARTH. Your puff of gas would only have that at a miniscule fraction of that. So where the ISS deorbits slowly anything would have to go through your gas trillions of times to feel the same effect.

and keep those gas molecules for a long enough time (years)

How? Please explain this. I've asked you four times already. How do you propose to get (let's say) 20 tonnes of gas to stay in a cloud of LEO atmaopheric density at above LEO orbit for years?

And even if this harebrained scheme worked: What of all the legitimate stuff that is floating around out there (you know: satellites?) You'd deorbit them along with everything else. Brilliant.
italba
2.3 / 5 (3) Jul 18, 2012
Well, "stupid is as stupid does". By repeating always the same things you seem to me like you WANT to do stupid.
1) Putting up a part of our atmosphere... We don't have to clean up the entire sky, just the orbits we need. I repeated it at least three times.
2) Trillions of tons of gas...trillions of times... How have you calculated it? Please do the math!!!
3) How you propose gas to stay in a cloud... Gas molecules will orbit like everything else, doesn't matter the mass of the single object. The gas will surely expand but, when the pressure will be low enough, the expansion will be very slow. Maybe years? Maybe.
4) Even if this harebrained scheme... Another stereotyped phrase you keep repeating on.
5) How not to deorbit satellites... Please repeat after me, and write it 1000 times on your elementary school copybook: I DON'T WANT TO CLEAN UP THE ENTIRE SKY!