Author Topic: Orbital Debris Cleanup - how to?  (Read 13114 times)

Offline Eer

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Orbital Debris Cleanup - how to?
« on: 10/10/2014 01:05 AM »
Ran across this from Les Johnson posted at Baen Publishing web site:

http://www.baen.com/Living_Without_Satellites.asp

It seems like this should be the subject of an X-prize or something.  There's a growing need for dedicated, autonomous or semi-autonomous solar-sail navigating space debris tugs that would individually (if the target is small enough) or in concert (fleet action) rendezvous with debris fragments and either decelerate them so they re-enter, or accelerate them so they raise their orbits out of harm's way (well above geosynchronous orbit).  Solar sails are not the only possible motive force - tethers using Earth's magnetic fields could also lend a hand.

Reusable, retaskable, long duration systems.  Perhaps larger craft would be regular customers of orbiting fuel depots.

There didn't appear to be a thread already discussing how to ultimately clean up orbital debris, so I started this, here.  Moderators, feel free to move/merge/delete as appropriate.

Offline floss

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Re: Orbital Debris Cleanup - how to?
« Reply #1 on: 12/04/2014 07:21 PM »
A rock in LEO would clean most of the lower orbits pretty well but no country would allow it .(gravity tractor)

Another larger rock outside GEO would drag the dead satellites out of GEO .

Offline nadreck

Re: Orbital Debris Cleanup - how to?
« Reply #2 on: 01/13/2015 10:02 PM »
Problem breaks down into several parts:

GEO (dead easy, a couple of big, ion engine equipped, tenders rounds up dead bodies and sticks them tethered together (they become a single target) in a temporary (several years) graveyard orbit a few hundred klicks further out until it is worth dragging the whole lot of them about 5 times further out with the last of the fuel on that tender. Eventually someone picks them up for scrap metal when there is an industry that might support using where it was cheaper than raw material. At this time I estimate that there is probably between 1,000 and 3,000 tons of non operational satellites in GEO.

Multi plane constellations in MEO and high LEO, should be required to have deorbit capability on each new bird launched, or a tender on each plane to do the same. Existing ones would be more practical to deal with with an ION engine equipped tender since you could remove all the birds from a given plane with one tender then deorbit the tender and its collection of satellites.

Individual birds and uncontrolled spare parts, boosters etc in MEO and mid to high LEO, plus ones in highly eliptical oribits are a bigger problem and definitely there should be provision for future craft to make sure all parts can de-orbit successfully on their own.  Craft to deal with these would have to have a huge ΔV budget to make any inroads into the collected waste that exist.

Low LEO, well, in future there probably should be some way of managing new birds, but the good news is that they will all eventually re-enter on their own. 

Things like experimental micro, nano and pico sats should, except in special cases, be in future kept in virtual corrals with a tender that takes out ones that have no control or lose control and wander outside the control area.

All of this of course is my opinion on how things should be done.
It is all well and good to quote those things that made it past your confirmation bias that other people wrote, but this is a discussion board damnit! Let us know what you think! And why!

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #3 on: 04/02/2016 03:49 AM »
My logic is:

- So we have a lot of space junk that orbits the Earth.
- A lot of space objects de-orbit themselves due to atmospheric drag.
- Let's create an artificial atmosphere to de-orbit this junk.
- Just deliver a 10mT of helium up to the orbit (in other direction of a space junk) and disperse it.
- It must create an atmospheric drag within hi-volumes of space.
- How much drag it will create, I do not know how to calculate this stuff.
- Upgraded idea: disperse some organic stuff that decay within couple of days due to UV-light. It will provide much more denser cloud.

Positive things:
- It's much cheaper than lasers or unmanned vehicles.
- It covers a lot of volume by one lunch.

Negative things:
- It will de orbit active satellites, but because of higher mass/front area ratio, the effect will be less than on smaller objects.

So, Is it viable?
 

Offline Lee Jay

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Re: Orbital Debris Cleanup - how to?
« Reply #4 on: 04/02/2016 03:55 AM »
Good idea.  But you don't need 10mt, you need more like a few hundred billion mt, and since it will disperse into space immediately, you'll need that every minute or so.

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #5 on: 04/02/2016 03:58 AM »
Good idea.  But you don't need 10mt, you need more like a few hundred billion mt, and since it will disperse into space immediately, you'll need that every minute or so.

Can you prove it mathematically? It sounds cool, just like my idea, but without calculations it does not make sense.

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #6 on: 04/02/2016 04:03 AM »
Good idea.  But you don't need 10mt, you need more like a few hundred billion mt, and since it will disperse into space immediately, you'll need that every minute or so.

Can you prove it mathematically? It sounds cool, just like my idea, but without calculations it does not make sense.

Just for the sake of argument. Image 10mT steel plate orbiting other way with delta v about 14km/s. Will it stop space junk? yes. Then image that it has 100 tin foil layers separated with 1mm. Will it stop it? Yes. Now image 1000000000 layers. Will it stop it? yes.

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #7 on: 04/02/2016 04:25 AM »
Welcome to the forum!

Good try, but there a quite a few problems with this.

1) you wouldn't use Helium because a) very expensive and b) very light so you wouldn't create as much drag as you might with a heavier gas.

2) You know space is big... right?  This is back of the envelope calculation so may be wrong:  Say you go for the worst region of debris at 600-1000km, that gives a volume of 2.4 x 10^20 cubic metres.  Your 10 mT of Helium works out to 0.25 Mmol or 1.5 x 10^29 Helium atoms.  That gives you a roughly 5*10^8 (half a billion) atoms per cubic metre of Helium, which might sound like a lot, until you find out that the density of atmosphere at 600km is already approx 0.1ng/cubic metre = 1.5 x 10^22 atoms per cubic metre.  So you're increasing the already existing atmospheric drag by 0.00000000000004%.

You need more gas to make this work... :)

3) ...of course then it's un-targeted - you take down your functional satellites as well as the space debris.  The US military may have a problem with this.

4) depending on what other agents you include, you may end up just generating more debris.

Whatever the solution is... it has to be targeted.  That much we know.

Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #8 on: 04/02/2016 04:31 AM »
Good idea.  But you don't need 10mt, you need more like a few hundred billion mt, and since it will disperse into space immediately, you'll need that every minute or so.

Can you prove it mathematically? It sounds cool, just like my idea, but without calculations it does not make sense.

Just for the sake of argument. Image 10mT steel plate orbiting other way with delta v about 14km/s. Will it stop space junk? yes. Then image that it has 100 tin foil layers separated with 1mm. Will it stop it? Yes. Now image 1000000000 layers. Will it stop it? yes.

The steel plate will stay together.  A cloud of gas will rapidly expand to be very, very, very diffuse -- so diffuse that it won't cause much drag.

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #9 on: 04/02/2016 04:53 AM »
until you find out that the density of atmosphere at 600km is already approx

Where did you get that data?

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #10 on: 04/02/2016 05:03 AM »
until you find out that the density of atmosphere at 600km is already approx

Where did you get that data?



from here:
https://books.google.com.au/books?id=HSffDG356TkC&pg=PA16&lpg=PA16&dq=atmospheric+density+at+600km
&source=bl&ots=CZydyEasWV&sig=sbxAy9MWGahJt18e4a7R_iQCVtM&hl=en&sa=X&redir_esc=y#v=onepage&q=
atmospheric%20density%20at%20600km&f=false

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #11 on: 04/02/2016 05:51 AM »
2) You know space is big... right?  This is back of the envelope calculation so may be wrong:  Say you go for the worst region of debris at 600-1000km, that gives a volume of 2.4 x 10^20 cubic metres.  Your 10 mT of Helium works out to 0.25 Mmol or 1.5 x 10^29 Helium atoms.  That gives you a roughly 5*10^8 (half a billion) atoms per cubic metre of Helium, which might sound like a lot, until you find out that the density of atmosphere at 600km is already approx 0.1ng/cubic metre = 1.5 x 10^22 atoms per cubic metre.  So you're increasing the already existing atmospheric drag by 0.00000000000004%.

I think you're wrong here, that is why:

Let's calculate the weight of atmosphere in volume shaped like torus with center radius of 7000km and tube radius 1km.

1. Volume: Torus volume formula: 2*pi^2*tube radius^2*center redius = 2 * pi * pi * 1km * 1km * 7000km  =~ 1.382 * 10^14 m3

2. Atmospheric density at 600km - http://www.wolframalpha.com/input/?i=Atmospheric+density+at+600km
1.1 * 10^-13 kg/m^3, your chart gives 10^-2ng/m3 ... 10^-14  kg/m3...

3. So we have the mass:  1.382 * 10^14 m^3 * 1.1 * 10^-13kg/m^3 = 1.382 * 10 ^ 1 * 1.1 kg =~ 13 kg of air.

4. Compare weight: 10mT = 10 ^ 4 kg vs 13 kg... 1:760

5. Now lets compare impulses:
Orbital speed at 600km:    7.56  km/s    ... 7.56 * 10^3 m/s

a) Atmosphere vs trash (atmosphere is static, which is probably not true)
mv^2/2 ... 13 * (7.56 * 10^3) ^ 2 / 2 =~ 3.715 * 10^8 J

b) Gas cloud at reverse orbit:

10000kg * (2 * 7.56 * 10^3) ^ 2 / 2 = 1.43 * 10^12 J


6. So kinetic energy is different, a vs b is 1:3849...

7. Orbit decay for debris: http://www.nasa.gov/news/debris_faq_prt.htm "Debris left in orbits below 370 miles (600 km) normally fall back to Earth within several years."

8. "Several years" just turned into several months thanks to only one Dragon launch.

Military still is not happy about that :)

 

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #12 on: 04/02/2016 06:02 AM »
Well okay, but launching into a reverse orbit has a large payload cost - not sure if a F9 is capable of launching 10 tons into that orbit, and by confining your calculations to a torus of radius 1km you're effectively doing a whole falcon launch to target an individual piece of space debris: by brownian motion (and with effectively zero air pressure) the gas will disperse beyond your 1km tube in approximately 3 seconds (speed of sound is ~333m/s) ;)

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #13 on: 04/02/2016 06:16 AM »
And anyway, there's actually a lot of useful materials/electronics in the so-called "space junk" and de-orbiting them is less desirable than having some kind of way to target and harvest them.  There are lot of otherwise fully functional satellites, that have just run out of battery/propellent, or have one fried circuit board.   At $10,000/kg to get it into orbit in the first place, it would be better if we can figure out an efficient way to recycle all the material that's up there.

Online KelvinZero

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Re: Orbital Debris Cleanup - how to?
« Reply #14 on: 04/02/2016 07:00 AM »
Well okay, but launching into a reverse orbit has a large payload cost - not sure if a F9 is capable of launching 10 tons into that orbit, and by confining your calculations to a torus of radius 1km you're effectively doing a whole falcon launch to target an individual piece of space debris: by brownian motion (and with effectively zero air pressure) the gas will disperse beyond your 1km tube in approximately 3 seconds (speed of sound is ~333m/s) ;)

Variations of this idea have been posted a few times. I had this idea myself.

In my scheme the material came from station keeping propellant fired with double your orbital speed to put it into a retrograde orbit. Obviously this stationkeeping propellant has to be something that is not itself a problem, or at least must be the lesser of two evils.

Certainly it will spread out, but the millions of targets are also spread out. That is why nets and hunting them down is not reasonable. I don't know whether it can be a gas or not. As far as I can see the only problem with a gas is that sunlight can knock it out of orbit. Otherwise it would just keep its momentum like any other satellite.

It is just a matter of statistics. For simplicity of argument, assume each satellite uses its its own mass in station keeping propellant over its life. Given that only a fraction of satellite mass will become dispersed dangerous fragments, there will be far MORE mass of the counter rotating material than of problem fragments.

Now just consider one dangerous fragment. The effect of the counterrotating gas must be small, but also the chance of this ONE particular fragment hitting a satellite is very VERY small... So the question is, on average, what mass of counterrotating material will this one fragment encounter before it encounters a satellite or station?

* You might start by saying "the mass of satelites and counterrotating material is equal, so if it hits a 1 ton satellite it has probably already encountered 1 ton of counterrotating material (..which would have slowed a nut or bolt out of orbit LONG ago)
* Then you could also observe you are also far more likely to encounter counter rotating material than things moving in roughly the same velocity as yourself, as is the case if you fell of a satellite in a commonplace orbit.
* Then you could also observe that due to the larger surface area/mass ratio of smaller objects, that  a cloud has the largest surface area to mass that you can achieve, so this biases you towards hitting it over discrete large objects.

..and also this gas will have more effect on small fragments with high surface area to mass than on large object that we might wish to keep in orbit, or could consider deorbiting by more directed means.

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #15 on: 04/02/2016 10:09 AM »
Well okay, but launching into a reverse orbit has a large payload cost - not sure if a F9 is capable of launching 10 tons into that orbit, and by confining your calculations to a torus of radius 1km you're effectively doing a whole falcon launch to target an individual piece of space debris: by brownian motion (and with effectively zero air pressure) the gas will disperse beyond your 1km tube in approximately 3 seconds (speed of sound is ~333m/s) ;)

Variations of this idea have been posted a few times. I had this idea myself.

In my scheme the material came from station keeping propellant fired with double your orbital speed to put it into a retrograde orbit. Obviously this stationkeeping propellant has to be something that is not itself a problem, or at least must be the lesser of two evils.

Certainly it will spread out, but the millions of targets are also spread out. That is why nets and hunting them down is not reasonable. I don't know whether it can be a gas or not. As far as I can see the only problem with a gas is that sunlight can knock it out of orbit. Otherwise it would just keep its momentum like any other satellite.
<snip>
..and also this gas will have more effect on small fragments with high surface area to mass than on large object that we might wish to keep in orbit, or could consider deorbiting by more directed means.

Ooh that's interesting, I never though of dual-purposing station-keeping thrust before.  But why go to the effort of trying to emit the gas at double-orbital speed? especially if you're just going to run into it half an orbit later (I guess that's a good reason to use gas since it will disperse).

Here's a thought for how to reduce that small fragment space junk:

What if your entire craft was basically one big nitrogen gas thruster, initially placed in at some low-inclination LEO.  You use SEP to rendezvous with each bit of junk - specifically you make sure the craft gets to the rendezvous point just moments before the junk, and then you release a relatively dense cloud of gas directly into the path of the junk.  This propels your craft forward, allowing it to work its way upwards through the altitudes, and also slows the junk down to (closer to) deorbit velocity.

EDIT: should clarify that I don't see the SEP having all that much to do, every bit of space junk has to pass through the equatorial plane at some stage - it might just need some kind of advanced radar in order to be able to get much closer to colliding at multiple km/s, without actually colliding.
« Last Edit: 04/02/2016 10:16 AM by mikelepage »

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #16 on: 04/02/2016 01:33 PM »
Looks like we have a plan.

Most dangerous space junk is small pieces. It also the most major group of space junk. Big pieces you can track/predict, it much harder to predict/avoid small pieces.

Gas as a way to de-orbit these kind of junk is the most efficient way.

I wonder, is it possible to get funding for research purposes for this project?

Offline spacenut

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Re: Orbital Debris Cleanup - how to?
« Reply #17 on: 04/02/2016 02:18 PM »
What about an orbiting powerful laser to just pinpoint the bad ones and burn them.  More efficient, as gas can affect good satellites. 

Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #18 on: 04/02/2016 02:29 PM »
What about an orbiting powerful laser to just pinpoint the bad ones and burn them.  More efficient, as gas can affect good satellites.

Nice way to test satellite destroyer. AFAIK They need a 747 plane to have chance to destroy ICBM with a laser. I think it's not feasible at this moment. You can try to prove otherwise.

Offline Stan-1967

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Re: Orbital Debris Cleanup - how to?
« Reply #19 on: 04/02/2016 02:49 PM »
This still won't work.  It is a flawed assumption to model whatever gas you lift to that altitude as a torus.  It will not remain a torus for any significant amount of time, certainly not even long enough for a single orbit needed to disperse the gas, indeed I do not think you can even explain how to make a torus in the first place.     Is the thruster emitting this gas going to operate/expell it for the +60 minute orbital period at altitude?   What will the orbital height be after thrusting for 60 minutes?   Unless your gas is an insignificant portion of the mass of the vehicle, you will be in a very different orbit due to the DV of the cold gas thruster.

 The gas will rapidly disperse into a spherical shell in the top of the atmosphere.   The gas will first disperse because it will flow according to the pressure gradient, which will be more or less equivalent in the orbital plane at whatever altitude you propose to release it. 

Furthermore, each gas particle will disperse with not only the velocity you impart from launching or expelling it from your thrusters, but also the thermal energy imparted by it's temperature.   Once in the space environment, the gas in only constrained from expanding off into space by the earths gravity.   As long as the velocity of each gas molecule is not greater than earth escape velocity, it will simply keep moving in its path until it collides with another gas molecule, and the dynamics of that collision will disperse the gas even more.  The gas will rapidly shed it's thermal energy by radiating heat into space until it is equilibrium with the local space environment.



Offline sevenperforce

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Re: Orbital Debris Cleanup - how to?
« Reply #20 on: 04/02/2016 02:50 PM »
Laser ablation would work well enough if the debris had a suitable surface. But using a cold gas thruster and an extremely close pass to drag and deorbit debris is a pretty good idea. I like it.

Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #21 on: 04/02/2016 04:16 PM »
* You might start by saying "the mass of satelites and counterrotating material is equal, so if it hits a 1 ton satellite it has probably already encountered 1 ton of counterrotating material (..which would have slowed a nut or bolt out of orbit LONG ago)

There are lots of flawed assumptions here, but I'll just point out this one for now.  Even if the gas stayed in the same orbit (it won't), this claim is false.  If a small piece of space debris hits a 1 ton satellite, you can't expect it to have already enountered 1 ton of counterrotating material.  You can expect it to have enountered whatever portion of the 1 ton satellite is in the cross-section of the debris that hits it.  For example, suppose it hits a spherical piece of debris with a 1 inch diameter.  Then the amount of counterrotating material you should expect it to have hit is the amount of the satellite in a 1-inch diameter hole through the satellite at the point of impact.  That is far less than 1 ton.

Any untargeted use of gas is a complete non-starter.  As others have pointed out, gas disperses far too quickly to do anything useful.

The only thing mentioned in this thread at all that has even the slightest hope of working is targeting an individual piece of debris and expending gas directly into its path immediately before the debris arrives.

And all talk of other debris-removal techniques is off-topic for this thread.  There are other threads for those other techniques.  Please take those discussions there.  This thread is only for discussing using gas to remove debris.

Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #22 on: 04/02/2016 04:29 PM »
While targeting an individual piece of debris and expelling gas in its path immediately before it arrives would slow the piece down, it's a terribly inefficient way to do it.  Consider a 1-inch diameter piece of junk.  How much gas are you going to expel in its path?  If you expel only enough that it stays in a 1-inch diameter ball, then all of the gas's momentum will be used to affect the path of the junk.  But the gas will be far less dense than the debris and of equal size, so it will have barely any effect -- certainly not enough to deorbit it.  If you want to have any significant effect on the orbit, you need a cloud of gas that is both huge and dense, so that the mass the piece of junk hits is a significant fraction of its own mass.  But that necessarily means the junk misses most of the mass expelled.  For example, if you want the debris to hit a volume of gas 10 times its own volume, you need a sphere of gas 10 times the diameter of the object.  That means the sphere of gas will have 1,000 times the total volume of the object, so only 1% of the mass of the gas will be encountered by the object.

This is a very, very, mass-inefficient way to do it, and also requires absurdly tight tolerances -- the gas has to be released at extremely high density a tiny fraction of a second before the object arrives and must be within inches of the right position.

Could it be done?  It would be very, very difficult and inefficient, but it could probably be done.  Is it a good idea?  Definitely not.  There are far better solutions.

Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #23 on: 04/03/2016 05:10 AM »
While targeting an individual piece of debris and expelling gas in its path immediately before it arrives would slow the piece down, it's a terribly inefficient way to do it.  Consider a 1-inch diameter piece of junk.  How much gas are you going to expel in its path?  If you expel only enough that it stays in a 1-inch diameter ball, then all of the gas's momentum will be used to affect the path of the junk.  But the gas will be far less dense than the debris and of equal size, so it will have barely any effect -- certainly not enough to deorbit it.  If you want to have any significant effect on the orbit, you need a cloud of gas that is both huge and dense, so that the mass the piece of junk hits is a significant fraction of its own mass.  But that necessarily means the junk misses most of the mass expelled.  For example, if you want the debris to hit a volume of gas 10 times its own volume, you need a sphere of gas 10 times the diameter of the object.  That means the sphere of gas will have 1,000 times the total volume of the object, so only 1% of the mass of the gas will be encountered by the object.

This is a very, very, mass-inefficient way to do it, and also requires absurdly tight tolerances -- the gas has to be released at extremely high density a tiny fraction of a second before the object arrives and must be within inches of the right position.

Could it be done?  It would be very, very difficult and inefficient, but it could probably be done.  Is it a good idea?  Definitely not.  There are far better solutions.

Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

Secondly, all your points are fair, but you are missing the main advantage of the idea as a solution to two conflicting needs:

1) Each piece of debris needs to be targeted individually, probably from relatively close range.
2) It is absurdly inefficient to have any effector craft match velocity with each piece of debris.

If the effector craft isn't matching velocity (the core of my idea above), that means contact velocities remain in the km/s range - and so we need a way to impart velocity on junk at that velocity, without generating more space debris... anything bigger than gas molecules at that velocity is going to generate debris.

Unless... (I could edit this down but I figure I'll let you see how my train of thought went)...

Unless you use something that will sublimate into gas in a vacuum.  That will be massive when the contact occurs, but which won't generate debris because it evaporates following the impact. 

What if you had a craft going along in a standard low inclination orbit as above, setting up rendezvous with junk where it arrives at the point moments before the space junk, but instead of just nitrogen gas, your cold-gas thruster powers an air-cannon which lobs chunks of dry ice (frozen CO2) at the debris?  Maybe you could even craft the "snowball" into a specific "cup" shape to cut down on any shrapnel that breaks away from the junk.

Sure, the accuracy of the snowball air cannon ;)  would have to be spectacular, but if the US military can bullseye one missile with another missile, I'm sure it must be possible, yeah?  Use your lasers not to ablate, but to do fine targeting, use secondary CGS or reaction wheels to adjust the aim of your cannon.  Your range is probably good for 5-10km before your snowball evaporates...

Come to think of it, I just conceptualised a perfect anti-sattelite weapon :P

EDIT: actually no, hitting anything bigger than a certain size with this would just generate more debris, but I think this would be good for small debris.
« Last Edit: 04/03/2016 05:20 AM by mikelepage »

Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #24 on: 04/03/2016 09:29 AM »
Could it be done?  It would be very, very difficult and inefficient, but it could probably be done.  Is it a good idea?  Definitely not.  There are far better solutions.

Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

One better solution: launch a huge mass of micro satellites to a particular orbit.  The micro satellites have solar-electric propulsion and a grapple.  Each of the thousands of micro sats targets a piece of debris that's in a somewhat close orbit.  It grabs it and de-orbits it.  Repeat for different orbital planes.

Does it require technology development?  Yes, definitely.  But so does a solution that does ultra-precise gas distribution.

I agree your snowball throwing idea is an improvement over the gas idea, but it's not what the thread is about and not what I was responding to.  I was responding to the original idea of the thread, which was specifically to use gas.  Gas is a bad idea for space junk mitigation.


Online KelvinZero

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Re: Orbital Debris Cleanup - how to?
« Reply #25 on: 04/03/2016 10:26 AM »
* You might start by saying "the mass of satelites and counterrotating material is equal, so if it hits a 1 ton satellite it has probably already encountered 1 ton of counterrotating material (..which would have slowed a nut or bolt out of orbit LONG ago)
There are lots of flawed assumptions here, but I'll just point out this one for now.  Even if the gas stayed in the same orbit (it won't), this claim is false.  If a small piece of space debris hits a 1 ton satellite, you can't expect it to have already enountered 1 ton of counterrotating material.  You can expect it to have enountered whatever portion of the 1 ton satellite is in the cross-section of the debris that hits it.
Um.. you might be right. I will think about that again.

However, if you are correct that would still be PLENTY of mass to have removed the object from orbit wouldn't it?

We are talking about small objects, say the size of a thumbnail that it is not practical to hunt down individually but are still large enough to be dangerous. Surely a thumbnailed or smaller object would encounter at least around its own mass in space-station, satellite or astronaut, considering cross-section alone. If it had previously hit its own mass in counterrotating material wouldn't it have dropped out of orbit long ago?

I used the word 'material' to avoid discussing the qualities of any particular gas or particle. Dispersing is fine with me because the debris in orbit is also dispersed. Clearly these dangerous-sized particles can stay in orbit a long time. The question is if non-dangerous sized particles can stay in orbit a useful time.

--- edit ---
Might have just spotted a flaw in my statistical argument. The time for a particular piece of debris to hit a satellite might be huge, eg many thousands of years. We only get hits because there are thousands of them. It is not too surprising if in many thousands of years they sweep out their own mass in super diffuse counterrotating material and are disorbited, but none of the collisons today or in the near future could possibly have had time to have swept out that much material.. Im not sure if the flaw means it would not work at all, because we are selecting for debris which specifically have not had sufficient time, or that it would take many thousands of years to reach a useful equilibrium where this strategy pays off.
« Last Edit: 04/03/2016 11:52 AM by KelvinZero »

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #26 on: 04/03/2016 05:11 PM »
Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

Always a good idea to look at what is actually being worked on, first.

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Technologies_for_space_debris_remediation


https://en.wikipedia.org/wiki/E.Deorbit
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Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #27 on: 04/03/2016 07:44 PM »
Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

Always a good idea to look at what is actually being worked on, first.

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Technologies_for_space_debris_remediation


https://en.wikipedia.org/wiki/E.Deorbit

I do not see here a better solution to remove small-size space junk.

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #28 on: 04/03/2016 07:49 PM »
Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

Always a good idea to look at what is actually being worked on, first.

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Technologies_for_space_debris_remediation


https://en.wikipedia.org/wiki/E.Deorbit

I do not see here a better solution to remove small-size space junk.

Because realistic solutions for tackling that problem are at very early technology development stage and not fully funded initiatives yet. Such as

http://www.spacesafetymagazine.com/space-debris/debris-removal/electrodynamic-debris-eliminator-receives-funding/
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Offline Lar

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Re: Orbital Debris Cleanup - how to?
« Reply #29 on: 04/03/2016 07:55 PM »
I do not see here a better solution to remove small-size space junk.
Thank you Savuporo for sharing that info. OlegSerov, try not to be so dismissive, please.
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Offline OlegSerov

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Re: Orbital Debris Cleanup - how to?
« Reply #30 on: 04/04/2016 01:01 AM »
Well firstly, I'm curious what you think the "better" solutions are? I've not yet seen any I consider "good".

Always a good idea to look at what is actually being worked on, first.

http://www.esa.int/Our_Activities/Space_Engineering_Technology/Clean_Space/Technologies_for_space_debris_remediation


https://en.wikipedia.org/wiki/E.Deorbit

I do not see here a better solution to remove small-size space junk.

Because realistic solutions for tackling that problem are at very early technology development stage and not fully funded initiatives yet. Such as

http://www.spacesafetymagazine.com/space-debris/debris-removal/electrodynamic-debris-eliminator-receives-funding/

From the video:
Collect space debris weighting more than 2 kg in a net and then de-orbit them...

In my opinion it does not qualify as a "small space junk". Medium size - yes, but not small size.

Also: "ee of maneuverability across LEO and would be capable of collecting 136 sun-synchronous objects over a 3 year period." It will take forever to do it.

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #31 on: 04/04/2016 01:47 AM »
Also: "ee of maneuverability across LEO and would be capable of collecting 136 sun-synchronous objects over a 3 year period." It will take forever to do it.
Thats the reality of it, there are no quick and easy solutions.

Gas dispersion based systems have by the way also been proposed and studied, this was a serious NIAC study :

https://www.nasa.gov/pdf/716066main_Gregory_2011_PhI_SpaDE.pdf

http://www.spacesafetymagazine.com/space-debris/debris-removal/air-bursts-present-option-handle-space-debris/

In summary, energy requirements are unrealistic, and high altitutde airborne platforms for carrying such systems do not exist. Hence, TRL 2 and NIAC phase studies only.
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Offline gospacex

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Re: Orbital Debris Cleanup - how to?
« Reply #32 on: 04/04/2016 02:20 AM »
My pet idea for dealing with small (say, up to 30 cm) space junk is to build a spacecraft designed to survive multiple collisions with such junk, then launch it and, indeed, collide with debris, or "sweep up" debris until spacecraft is no longer redundant enough to be controllable after next expected collision or two. Then deorbit.

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Re: Orbital Debris Cleanup - how to?
« Reply #33 on: 04/04/2016 02:23 AM »
The net idea has good potential.   The problem according to ESA's roadmap is more in the guidance algorithms and sensors needed to capture the debris.   That is probably very challenging for smallsats, but in time, that would be ideal. 

I do wonder if a solid thin walled container would be better than a net.  I also think the intake capture mechanism should be something like a rear loading garbage truck, where there is a retainer plate to keep the already loaded garbage from falling out.   You basically have a "hopper" bin for capture, then push the debris back into the container.


I see a difficult trade for maximizing the mass and number of captured objects vs. the DV available for maneuvering and de-orbiting.

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #34 on: 04/04/2016 02:26 AM »
Here is a relatively recent summary talking about all currently proposed ADR ( active debris removal) methods, including dust, nets, ion, foam, airburst, lasers etc. and goes into pros and cons of each a little, too.

https://www.mcgill.ca/iasl/files/iasl/mlc-2014-burgess.pdf
http://www.rcaf-arc.forces.gc.ca/en/cf-aerospace-warfare-centre/elibrary/journal/2014-vol3-iss4-04-active-space-debris-removal-an-inevitability.page
http://www.rcaf-arc.forces.gc.ca/assets/AIRFORCE_Internet/docs/en/cf-aerospace-warfare-centre/elibrary/journal/2014-vol3-iss4-04-active-space-debris-removal-an-inevitability.pdf

They all have downsides, and statistically, the biggest threats are the large debris pieces. Thats why ESA is working on AR&D techniques and a demo for larger targets.
« Last Edit: 04/04/2016 02:27 AM by savuporo »
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Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #35 on: 04/04/2016 05:57 AM »
Thanks for the links savuporo.  I hope everyone reads them.

Biggest take-home I gained from them is that if the objective is to at least maintain the status quo, that requires the removal of 5 or more large objects per year.  Large objects are chosen presumably because they are easier to target than the multitude of smaller objects which might collide into the large objects and create hundreds or thousands more small, hard-to-track objects.

Side note: I'm now avoiding use of the word "rendezvous" because it seems people often equivocate between two senses of it: 1) imply "match velocities with" or 2) "be in the same place at the same time".  Makes a big impact as far as space debris goes (rimshot).

For large objects above a certain size, it makes sense to have effector craft match velocities with the junk and deorbit/control it.

The much more prevalent small junk is going to remain an increasing problem however, and there are so many pieces in this category that it doesn't make sense to have an effector craft match velocities with them.

It seems to me the best solution is a two pronged approach with 1) matching velocities and netting large objects (which has a tech crossover with the asteroid redirect mission),  and 2) having a non-velocity-matching snowball cannon such as proposed above, or similarly using the Tungsten dust or air vortex methods mentioned in the links.

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #36 on: 04/04/2016 06:27 AM »
Large objects are chosen presumably because they are easier to target than the multitude of smaller objects which might collide into the large objects and create hundreds or thousands more small, hard-to-track objects.
Simply put, large objects represent a much bigger amount of stored kinetic energy ( E = 0.5 * m * v2 ) . On collision that energy will disperse and can have potentially catastrophic cascading effects.
Say a loose orbiting bolt slamming and puncturing ISS is not nearly as bad as two small LEO satellites in a head on collision.
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Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #37 on: 10/29/2016 07:12 PM »
A new interesting paper to add
Ranking upper stages in low Earth orbit for active removal
Quote
5. Conclusions
The proposed ranking scheme was preliminarily applied to 529 rocket bodies in LEO, belonging to just 5 types, but accounting  for  more  than  64%  of  the  total  number  and  nearly  73%  of  the  total  mass  of  upper  stages  with  a  mean altitude below 2000 km. In terms of debris environment criticality, the sample analyzed was cumulatively equivalent to  1136  average  intact  objects  into  an  800  km  sun-synchronous  orbit,  with  a  mean  RN = 2.15 per  object.
  The environmental criticality was largely dominated by the 20 massive Zenit-2 second stages between 800 and 1000 km, followed by the Kosmos second stages, mainly between 750 and 1000 km,by the Tsiklon-3 third stages, around 950 km, by the Vostok second stages, between 800 and 900 km, and by the Delta 1 and 2 second stages, broadly scattered between 700 and 1800 km (Figures 6, 7 and 8 ). A further significant presence of Kosmos and Tsiklon-3 upper stages, even though quite lesser in terms of criticality ranking, was found between 1350 and 1600 km.


« Last Edit: 10/29/2016 07:15 PM by savuporo »
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Re: Orbital Debris Cleanup - how to?
« Reply #38 on: 12/06/2016 11:23 PM »
Natalie Panek:"Let's clean up the space junk orbiting earth" - TED Talk

Quote
Our lives depend on a world we can't see: the satellite infrastructure we use every day for information, entertainment, communication and so much more. But Earth orbit isn't a limitless resource, and the problem of space debris will get worse without a significant change to our behavior. Natalie Panek challenges us to consider the environmental impact of the satellites we rely on. Our orbital environment is breathtakingly beautiful and our gateway to exploration, she says. It's up to us to keep it that way.

http://www.ted.com/talks/natalie_panek_let_s_clean_up_the_space_junk_orbiting_earth?
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Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #39 on: 12/12/2016 12:57 AM »
This thread was started to discuss one particular idea for removing space junk.

Some of the replies were about that specific idea.  But it has also become a magnet for any post at all about cleaning up space junk by any method.

Is there a generic thread for space junk removal in general?  If not, could we create one?  Then maybe we could get the mods to move the posts in this thread that aren't related to the original idea in this thread to that other thread and use that one going forward for the general topic of cleaning up space junk.

Offline Lar

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Re: Orbital Debris Cleanup - how to?
« Reply #40 on: 12/12/2016 01:09 AM »
I didn't search exhaustively but don't know of one. PM me if one is located.

https://forum.nasaspaceflight.com/index.php?topic=35812.0  (Thanks, AnalogMan)

I have a mind just to merge the threads as there are a few posts that it's hard to decide which one they go into. 

Edit: Merged.
« Last Edit: 12/12/2016 01:49 PM by Lar »
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Online KelvinZero

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Re: Orbital Debris Cleanup - how to?
« Reply #41 on: 12/13/2016 05:56 AM »
This is a general thread now?

How about thinking of the problem in terms of point defence that is also suitable to gradually reduce the total population of debris?

https://en.wikipedia.org/wiki/Point-defence

What I mean is, a specific vulnerable target like a space station could have a few really heavy defences, like missiles to take out large things that are just going to hit it otherwise.. don't worry about the fact this adds to the junk. First priority is to not be hit by a one ton piece of junk because that will really create a lot of junk.. out of you. Then you have a series of successively smaller defences that can also be turned on anything that happens to pass through say a 10km vicinity. Some are sustainable such as lasers, some would be somewhere in between like perhaps hosing water or dust in the general direction of an incoming object.

An advantage of this is that if you ace the point defence aspect you immediately solve the problem for your most critical infrastructure, and reducing/managing risk universally over time is just a bonus.

Offline john smith 19

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Re: Orbital Debris Cleanup - how to?
« Reply #42 on: 12/13/2016 11:01 AM »
I've just read through this thread and it seems the problem can be split on several different axes, such as debris size, life time, damage potential, number of pieces of a particular size etc.

My instinct is we are dealing with (very roughly) an exponential curve of size versus numbers. A small number of big items with a long tail of huge numbers of small items, down to paint fragment size. But because of the differential velocities involved it only takes a few small particles to hit some big objects and you get a massive cascade of debris. AFAIK people are a lot more aware of this for big objects like shrouds or boosters and take much more care to ensure either prompt de-orbiting or leaving in very high orbits.

So one question is what objects can you see? IIRC ground radar is limited to objects above 5cm in dia and that misses a lot that's still big enough to cause plenty of damage. If you can see it you can either avoid it or do something about it.

That suggests some sort of debris monitoring satellite or constellation with an orbit at least just above that of ISS (for debris warning), possibly up to say the fringes of the Van Allan belt. That means either millimetric radar or IR

Active measures are more difficult. IIRC ESA have  a low level study using a tank of gas on a satellite that "puffs" a cloud in front of debris, essentially a brick wall at these altitudes and densities, creating a sort of mini reentry.

I think any effective solution to the massive numbers of small fragments must act over a volume of space.

The tether concept seems quite energy and propellant efficient but still too small scale, too targeted.

 My instinct is to generate a UV light curtain, creating a positive surface charge on every object that passes across it. Over time the interaction of the objects charge with the Earths magnetic field will concentrate the debris into a higher or a lower orbit. Continued exposure should increase the charge on the debris and force it into lower or higher orbits, ideally leading to burn up in the denser atmosphere.
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Offline mikelepage

Re: Orbital Debris Cleanup - how to?
« Reply #43 on: 12/15/2016 03:20 AM »
Active measures are more difficult. IIRC ESA have  a low level study using a tank of gas on a satellite that "puffs" a cloud in front of debris, essentially a brick wall at these altitudes and densities, creating a sort of mini reentry.

Can you remember where you saw this? I've seen similar suggestions from ESA (although the one I found was using the gas to propel a net), and Boeing.  If you've got any references that would be awesome.

I've been workshopping a somewhat similar concept with some engineers that I know, but the economics of my idea will sink or swim based on the precision of the known path of the targeted bit of debris (i.e. if you imagine a cylindrical shaped volume in space through which the targeted piece debris is likely to pass, what's the radius of that cylinder?).

The graph I'm really hoping to see is (for a given orbital altitude):
X-axis: size of the debris
Y-axis: standard error of path of debris (in m).


Offline john smith 19

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Re: Orbital Debris Cleanup - how to?
« Reply #44 on: 12/15/2016 08:10 AM »
Can you remember where you saw this? I've seen similar suggestions from ESA (although the one I found was using the gas to propel a net), and Boeing.  If you've got any references that would be awesome.
I think it in an article on The Register. I dimly recall it was awarded to some defense contractor. Raytheon?
Quote
I've been workshopping a somewhat similar concept with some engineers that I know, but the economics of my idea will sink or swim based on the precision of the known path of the targeted bit of debris (i.e. if you imagine a cylindrical shaped volume in space through which the targeted piece debris is likely to pass, what's the radius of that cylinder?).

The graph I'm really hoping to see is (for a given orbital altitude):
X-axis: size of the debris
Y-axis: standard error of path of debris (in m).
That sounds like you need to look up the specs for one of the space object tracking radars the US or Russia uses.  I'm pretty sure they have real trouble with anything below 5cm. Viable for a system like this to de orbit but still very dangerous for anything else in orbit.

IIRC the idea was to get in close and squeeze out a pulse of gas. The problem is a gas cloud will disperse very fast.

Such a system will either need ground radar data to get it to target or have some kind of active sensor on board. The ideal case would be if you can find a debris swarm in close proximity and hit them all in one go.

One subtle point of these systems is the gas being expelled will act as a thruster in its own right, unless ejected through a T shaped nozzle to eliminate torque or thrust. Then you'd lose half the gas in the wrong direction.
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Re: Orbital Debris Cleanup - how to?
« Reply #45 on: 12/16/2016 07:37 AM »
Active measures are more difficult. IIRC ESA have  a low level study using a tank of gas on a satellite that "puffs" a cloud in front of debris, essentially a brick wall at these altitudes and densities, creating a sort of mini reentry.

I think any effective solution to the massive numbers of small fragments must act over a volume of space.
Do you have a reference on active measures being harder? I don't exactly dispute it but Im not sure in what sense you mean it. In some senses it is trivially true.

Im attracted to the idea of point defence because the difficulty is largely in vision and control, things that could advance very quickly through things such as computing power and programming. Otherwise you are dealing with difficulties based on physical properties such as the sheer volume of cislunar space, perhaps better performing materials, more efficient propulsion and so on.

Also there is the motivation that it defends your most critical targets immediately. Otherwise you are just talking about statistically managing the problem, eg a really exceptional solution might reduce the risk by a factor of 10 in a decade. This could also justify the system being funded for reasons of pure self interest rather than the long term greater good.. not typically something corporations and nations put a high dollar value on.

Offline john smith 19

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Re: Orbital Debris Cleanup - how to?
« Reply #46 on: 12/16/2016 08:04 AM »
Do you have a reference on active measures being harder? I don't exactly dispute it but Im not sure in what sense you mean it. In some senses it is trivially true.
No. I mean in the sense most of these concepts seem to send up a vehicle in order to bring down one piece of debris. This is expensive, unless you can build a vehicle like a cubesat that can de-orbit a booster, or a big panel or some other large object and you can make a lot of them.In this regard a spooled tether looks like a good system provided a spool you could put in a cube sat has the current carrying capacity to survive while having the flexibility to be coiled in the first place.
Quote
Im attracted to the idea of point defence because the difficulty is largely in vision and control, things that could advance very quickly through things such as computing power and programming. Otherwise you are dealing with difficulties based on physical properties such as the sheer volume of cislunar space, perhaps better performing materials, more efficient propulsion and so on.
Well Dragon already uses an image recognition system for docking so the computing level is there. But what about cislunar space? The trouble's in LEO due to the 60 years of accumulated launch debris.

In truth I'd like to see some stats on object sizes, quantities and altitude to get a feel for the problem. My instinct is the number of items is inversely exponential in size. A few big ones and a lot of small stuff.
Quote
Also there is the motivation that it defends your most critical targets immediately. Otherwise you are just talking about statistically managing the problem, eg a really exceptional solution might reduce the risk by a factor of 10 in a decade. This could also justify the system being funded for reasons of pure self interest rather than the long term greater good.. not typically something corporations and nations put a high dollar value on.
Again a lot of the concepts I've seen seem to be of the "launch a complex engineered vehicle to down a panel of junk." This makes no sense to me.  :( Likewise if it's big enough to see from the ground (and AFAIK that's where all current sensors are) it can be avoided unless something else hits it and changes it's course suddenly.

The idea of using UV to charge objects in space so they are acted upon by the Earth's magnetic field can be done at any size and can affects any size of object (although changes in delta vee of larger objects will be slower) and will run till the light source fails. Modern Excimer lamps can run 40% efficient. Even if they don't re-enter they would "herd" debris into a smaller volume for more efficient clean up by other methods.
« Last Edit: 12/16/2016 08:07 AM by john smith 19 »
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Offline Eer

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Re: Orbital Debris Cleanup - how to?
« Reply #47 on: 12/16/2016 11:00 AM »
It's been about a year since I posted the OP for this thread.  I didn't really intend it to be a specific solution thread, so I'm glad it has become a general thread for the topic.

It occurs to me, reading back over the replies, that the techniques for corralling and containing small-to-medium sized debris in various orbits is not too different from that faced by asteroid miners.

Maybe some of the asteroid mining companies will get a chance to test their approaches for capturing loosely aggregated asteroids on LEO debris.  Win-win.

Offline Lar

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Re: Orbital Debris Cleanup - how to?
« Reply #48 on: 12/16/2016 01:29 PM »
This is a general thread now?
Yes, after the suggestion was made to move the general posts to the other thread, I decided to merge them together instead. General posts and other suggestions make up the majority of this thread now, and the "ball of gas" idea is now just one of many.  Cleaner. and we have one decent sized thread instead of two smaller ones, one languishing and one mostly offtopic from the thread title...

If you like that, like this post. If you hate that, PM me and prepare for sarcastic replies :)
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Re: Orbital Debris Cleanup - how to?
« Reply #49 on: 12/16/2016 01:39 PM »
I think sending up one vehicle to get one piece of debris is not efficient. What's needed is an approach where the vehicle deorbits something but doesn't itself deorbit. That's where tethers shine, they are propellantless drives.

Japan's recent H-II tests tethers

http://www.upi.com/Science_News/2016/12/09/Japan-launches-space-trash-collector-to-ISS/5321481305090/

But I'm trying to find an earlier study in which a vehicle repeatedly travels to, attaches to, changes orbit of, and releases debris so it deorbits, but the vehicle climbs back to safety after release. One piece after another without using up any reaction mass... My google-fu is failing me right now but it's out there. It even had a video game like simulation of what cleanup looks like over time.

Edit: Found it

http://www.star-tech-inc.com/id121.html   "EDDE" ... It looks like there hasn't been recent progress. Maybe this didn't pan out but the idea of a craft that operates indefinitely is very attractive.

NOTE: initially it could deorbit but eventually it could bring things to a central location for recycling.
« Last Edit: 12/16/2016 01:57 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Lar

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Re: Orbital Debris Cleanup - how to?
« Reply #50 on: 12/16/2016 09:14 PM »
I reached out to the EDDE guys and got a note from Jerome Pearson back ...

He included this video back which nicely summarizes several approaches



I keep forgetting that EDDE is both tethers AND nets... tethers to move around, nets to capture. So any given device eventually runs out of nets.

Jerome also pointed me at this recent presentation by them which describes other uses that lead to the full capability.
http://www.star-tech-inc.com/papers/EDDE_Presentation_For_2016_Tether_Conference_as_submitted.pdf

and this other one which delves more into probability of collision, costs of mitigation and some concrete suggestions on next steps.

http://www.star-tech-inc.com/papers/Cost-Effective_Management_of_Orbital_Debris_for_CODER_2016Nov09.pptx
« Last Edit: 12/16/2016 09:28 PM by Lar »
"I think it would be great to be born on Earth and to die on Mars. Just hopefully not at the point of impact." -Elon Musk
"We're a little bit like the dog who caught the bus" - Musk after CRS-8 S1 successfully landed on ASDS OCISLY

Offline Space Invaders

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Re: Orbital Debris Cleanup - how to?
« Reply #51 on: 12/26/2016 12:38 PM »
A non-technological (partial) solution to the problem: slap a tonnage-based tax on new satellites which are not equipped with an effective deorbiting system. This would provide a strong economic incentive for satellite makers and/or operators to ensure their satellites can be safely deorbited at the end of their lifetimes.

Once all new satellites are equipped with deorbiting systems, it's just a matter of waiting for atmospheric drag to bring down old space junk.
« Last Edit: 12/26/2016 12:38 PM by Space Invaders »

Offline Hanelyp

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Re: Orbital Debris Cleanup - how to?
« Reply #52 on: 12/26/2016 11:17 PM »
Who'd collect this tonnage tax?  How hard would it be to launch from another jurisdiction?

Offline Jim

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Re: Orbital Debris Cleanup - how to?
« Reply #53 on: 12/27/2016 12:44 AM »
A non-technological (partial) solution to the problem: slap a tonnage-based tax on new satellites which are not equipped with an effective deorbiting system. This would provide a strong economic incentive for satellite makers and/or operators to ensure their satellites can be safely deorbited at the end of their lifetimes.


Not plausible for GSO sats

Offline M.E.T.

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Re: Orbital Debris Cleanup - how to?
« Reply #54 on: 12/27/2016 05:40 AM »
Large debris seems to be the easier of the two problems to deal with. So let's dwell on the small debris issue for a moment.

Supposing BFR/ITS becomes operational and we are able to place a 747-sized laser system in orbit.

How effectively could such a system vaporize 5cm and smaller sized debris? Would 5 minutes of laser burn time be sufficient to eliminate one small piece of debris? If so, the system could vaporize 105,000 pieces of small debris per annum.

If its lifetime is 10 years that's about 1 million pieces of debris removed for each laser deployed in space.

Is this a potentially feasible solution?
« Last Edit: 12/27/2016 05:42 AM by M.E.T. »

Offline rklaehn

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Re: Orbital Debris Cleanup - how to?
« Reply #55 on: 12/27/2016 07:18 AM »
Large debris seems to be the easier of the two problems to deal with. So let's dwell on the small debris issue for a moment.

Supposing BFR/ITS becomes operational and we are able to place a 747-sized laser system in orbit.

How effectively could such a system vaporize 5cm and smaller sized debris? Would 5 minutes of laser burn time be sufficient to eliminate one small piece of debris? If so, the system could vaporize 105,000 pieces of small debris per annum.

If its lifetime is 10 years that's about 1 million pieces of debris removed for each laser deployed in space.

Is this a potentially feasible solution?

I don't think you have to completely vaporise small debris. For LEO debris, just vaporise a small amount to lower perigee and cause reentry. See for example https://e-reports-ext.llnl.gov/pdf/386492.pdf

I think if there was an economic incentive for space debris removal, one of the proposed technical solutions like the one mentioned above, or something nobody has yet thought of, could definitely be made to work.

The question is how you get this economic incentive.
Try the ISS 3D visualization at http://www.heavens-above.com/ISS_3D.aspx

Offline john smith 19

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Re: Orbital Debris Cleanup - how to?
« Reply #56 on: 12/27/2016 11:45 AM »
I think if there was an economic incentive for space debris removal, one of the proposed technical solutions like the one mentioned above, or something nobody has yet thought of, could definitely be made to work.

The question is how you get this economic incentive.
Exactly. That's the core problem for any system that has any kind of consumable component.

Obvious options involve international agreements among all nations with launch capability.  The joker is would one of them not join, seeing it as an economic disadvantage to them.

The other obvious avenue is if launch insurance companies set aside some of their premiums to fund such a system. This could be incorporated into a discount dependent on how well the launch looks after debris cleanup.

I don't believe it's possible to do a completely debris free launch but I think there are degrees of how much debris a launch causes. that said in LEO fragments can be just as dangerous as bigger objects and are both much harder to track and much less predictable in their path.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline Space Invaders

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Re: Orbital Debris Cleanup - how to?
« Reply #57 on: 02/05/2017 03:56 PM »
Who'd collect this tonnage tax?  How hard would it be to launch from another jurisdiction?
The tax would be collected by the jurisdiction where the launch service provider is based. Since all major spacefaring nations have a strong interest in preventing too much space junk, getting them on board would already cover > 99% of satellite launches.

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Re: Orbital Debris Cleanup - how to?
« Reply #58 on: 02/05/2017 04:43 PM »
Large debris seems to be the easier of the two problems to deal with. So let's dwell on the small debris issue for a moment.

Supposing BFR/ITS becomes operational and we are able to place a 747-sized laser system in orbit.

How effectively could such a system vaporize 5cm and smaller sized debris? Would 5 minutes of laser burn time be sufficient to eliminate one small piece of debris? If so, the system could vaporize 105,000 pieces of small debris per annum.

If its lifetime is 10 years that's about 1 million pieces of debris removed for each laser deployed in space.

Is this a potentially feasible solution?



I may be over thinking this but when I first read your post  on orbiting a 747 sized laser system, I immediately thought of a scaled down but easily scaled up version of SDI......are countries, like Russia, going to be happy with a laser zapping system orbiting overhead....??

Offline Hanelyp

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Re: Orbital Debris Cleanup - how to?
« Reply #59 on: 02/05/2017 10:01 PM »
Laser vs. a ground target isn't going to work well because of atmospheric effects.  But it could still work against high altitude aircraft and functional satellites, making a laser based sweeper a military concern.

Offline saliva_sweet

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Re: Orbital Debris Cleanup - how to?
« Reply #60 on: 02/08/2017 06:05 PM »
Would it be possible to use space debris as reaction mass in a plasma thruster? Wouldn't need high isp or thrust. Take a chunk of debris and blast it with a bunch of lasers and arc welders to make plasma, accelerate the plasma. Use it to bring big stuff to faster decaying orbits and move to next object. Or just eat up the whole piece of debris altogether.

Offline CameronD

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Re: Orbital Debris Cleanup - how to?
« Reply #61 on: 02/09/2017 02:37 AM »
In case anyone was wondering, a solution to this problem was found in the '70s:



https://en.wikipedia.org/wiki/Quark_(TV_series)

LOL. I loved that show.  :)
« Last Edit: 02/09/2017 02:38 AM by CameronD »
With sufficient thrust, pigs fly just fine - however, this is not necessarily a good idea. It is hard to be sure where they are
going to land, and it could be dangerous sitting under them as they fly overhead.

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Re: Orbital Debris Cleanup - how to?
« Reply #62 on: 08/26/2017 07:28 AM »
In case anyone was wondering, a solution to this problem was found in the '70s:


LOL. I loved that show.  :)

That's sort of the image people have of this but IRL the trouble comes from the micro meteroids. The big stuff you can mostly avoid.

Unfortunately the "big stuff" IE anything visible on ground based radar, is already a couple of million objects. That's anything > 10cm

https://www.nasa.gov/centers/wstf/laboratories/hypervelocity/mmod.html

Look at some of this stuff. Literally chips of paint and flecks of Aluminum. But between this and the radar visibility limit there's a world of "stuff." Even something with a fairly low delta v. A hit from a bolt with a delta v of "only" a few hundred m/s would feel remarkably like being shot with a .45 hand gun.  :(

That said if you can approach them with a low enough delta v you could probably put them in a lightweight bag until you get enough of them to make de-orbiting the bag so it burns up worthwhile.

The trouble is any system that does this has do be able to
a)Cover a large volume of space, either on its own or part of a team of such "sweepers"
b)Be very cheap per item. The number of items that can be ground radar tracked is a million+.

I don't think anyone has any clear idea of what the density of sub 10cm sized objects is on orbit. This definitely sounds like for a cubesat mounted lidar to map the debris on orbit.
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline gospacex

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Re: Orbital Debris Cleanup - how to?
« Reply #63 on: 08/26/2017 12:52 PM »
I favor dedicated large-area satellites in retrograde orbits as a solution to small debris problem. "Sweep it up".

Offline edkyle99

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Re: Orbital Debris Cleanup - how to?
« Reply #64 on: 08/26/2017 06:58 PM »
I believe that the first step is to get some smart people together from all across the globe to work up a list that prioritizes objects for de-orbiting or other removal.  My guess is that the group would be very interested in the satellites with nuclear reactors that whiz a few hundred miles above our heads daily, some of which have begun to break apart.  The group would also be interested in the satellites with nuclear batteries and the like, and in satellites and upper stages that tend to explode after years in orbit. 

After making the list, the next step is simple.  Go get them.  One at a time.  Very carefully.

 - Ed Kyle 

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Re: Orbital Debris Cleanup - how to?
« Reply #65 on: 08/26/2017 07:07 PM »
I favor dedicated large-area satellites in retrograde orbits as a solution to small debris problem. "Sweep it up".
Let me suggest that this is more the level of technology that should be being used to handle this task.


https://www.ebay.co.uk/p/2-X-Strong-Garden-Bag-Waste-Refuse-Rubbish-Grass-Sack-Waterproof-Reusable-Large/1244753265?iid=371428185507
"Solids are a branch of fireworks, not rocketry. :-) :-) ", Henry Spencer 1/28/11  Averse to bold? You must be in marketing."It's all in the sequencing" K. Mattingly.  STS-Keeping most of the stakeholders happy most of the time.

Offline ppnl

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Re: Orbital Debris Cleanup - how to?
« Reply #66 on: 08/27/2017 12:05 AM »
I wonder if you could deorbit small objects with a cloud of ice crystals. Put a satellite in a retrograde orbit and have it fire ice as it crosses the orbit of other objects. 

Offline Comga

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Re: Orbital Debris Cleanup - how to?
« Reply #67 on: 08/27/2017 03:31 AM »
Please don't insult the intelligence of the professionals who consider this issue day in and day out.
There are many reasons all suggestions here are not feasible, either from technical or financial or diplomatic reasons, and sometimes all of the above.
Ice crystals sublimate.
"Retrograde orbits" hardly makes sense. Almost all are retrograde to something.
Gas clouds dissipate immediately
You can't get to low relative velocities with more than a tiny fraction of the stuff in 6 DoF orbits.
Some consider uncooperative grappling to be an anti-satellite technology
And it goes on and on.
(I actually tried proposing one of these. Came upon an immoveable roadblock quickly.)
What kind of wastrels would dump a perfectly good booster in the ocean after just one use?

Offline saliva_sweet

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Re: Orbital Debris Cleanup - how to?
« Reply #68 on: 09/20/2017 08:32 PM »
Some consider uncooperative grappling to be an anti-satellite technology

Any space debris cleanup is an anti satellite technology by definition. Are you saying the whole concept and any discussion of it should be abandoned?

Offline ChrisWilson68

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Re: Orbital Debris Cleanup - how to?
« Reply #69 on: 09/20/2017 08:52 PM »
Please don't insult the intelligence of the professionals who consider this issue day in and day out.
There are many reasons all suggestions here are not feasible, either from technical or financial or diplomatic reasons, and sometimes all of the above.
Ice crystals sublimate.
"Retrograde orbits" hardly makes sense. Almost all are retrograde to something.
Gas clouds dissipate immediately
You can't get to low relative velocities with more than a tiny fraction of the stuff in 6 DoF orbits.
Some consider uncooperative grappling to be an anti-satellite technology
And it goes on and on.
(I actually tried proposing one of these. Came upon an immoveable roadblock quickly.)

Well, I for one disagree 100% with Comga about the idea that people shouldn't post their ideas.  Please, don't anyone let him discourage you from posting.

It's not an insult to other people's intelligence to discuss your ideas with an open mind.  Even if you post something that turns out to be impractical, that's OK, that's how people learn.  It's really the whole point of forums like this.

And, on the particular issue that Comga seems to be replying to (shooting a cloud of ice crystals), I don't think the fact that they sublimate automatically disqualifies the idea.  Of course they sublimate after some period of time, but in the window between being ejected and sublimating, they might be effective.

Probably impractical in the end, but worth further discussion, in my opinion.

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #70 on: 09/20/2017 09:10 PM »
I believe that the first step is to get some smart people together from all across the globe to work up a list that prioritizes objects for de-orbiting or other removal.  ...
This has been done, there are conferences and workshops all the time, coordinated by international bodies.
The consensus seems to be that biggest immediate wins in terms of mitigating hazards are in going after large pieces of debris, like spent upper stages etc.

Orion - the first and only manned not-too-deep-space craft

Offline savuporo

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Re: Orbital Debris Cleanup - how to?
« Reply #71 on: 09/23/2017 06:54 AM »
Orion - the first and only manned not-too-deep-space craft

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