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Assuming you manage to grab a hold of debris without ripping off even tiny parts, how would you dispose of it? You'd need to deorbit it and you need a working e

Assuming you manage to grab a hold of debris without ripping off even tiny parts, how would you dispose of it? You'd need to deorbit it and you need a working engine for that. So a reusable collector doesn't seem like a plausible concept to me.

tomc1985 6y ago
Could an astronaut grab a smaller satellite and simply chuck it towards the sun? Would it have enough velocity break out of earth orbit or would it just get stuck in some really large, wide, graveyard orbit? If not the sun then maybe the earth? That would be a fun spacewalk.
- DavidSJ 6y ago
  The ∆v to escape Earth orbit is generally quite large, and it's far, far greater still to collide with the Sun (though this wouldn't normally be considered necessary). In comparison, a deorbit burn is usually relatively inexpensive.
- deleted 6y ago
  [deleted]
- taejo 6y ago
  From low Earth orbit, delta-v to Earth and to escape the solar system are about the same. Delta-v to fall into the sun is two orders of magnitude bigger.
  - labawi 6y ago
    Directly. Not if you take it the long way - near escape to reduce orbital speed, a little push to cancel the rest, and you will fall directly into the Sun (with a high velocity).
- dmoy 6y ago
  It would be difficult for an astronaut to chuck an object with over 32,000m/s of delta-v. For comparison, the fastest bullets go like ~1,500m/s, and they are very very very small.
  - darkwizard42 6y ago
    I think the goal would be to first accelerate the astronaut to that level of velocity and then relatively adjusting its trajectory isn't so difficult. But, that is just my understanding that speed is relative (especially in space with no drag)
    - morlockabove 6y ago
      Speed is also extremely expensive due to the rocket equation- changing your velocity, that is.
    - dmoy 6y ago
      It would surely be easier to accelerate space trash into the sun than it would be to accelerate both the astronaut and space trash into the sun. I don't think we should do either of those, but less mass is always easier to speed up.
  - tomc1985 6y ago
    If I chuck a baseball out of an airplane I don't have to worry about accelerating the baseball to the airplane's speed, as I am also traveling at that speed. Similarly, if a satellite is light enough in low-G to grab and manipulate from a craft that has straddled up along side it, would a single astronaut have enough strength to use his arms to put a satellite on a path that is effectively out of the way? Or could they just chuck it back at the earth so it can burn up on reentry?
    - dmoy 6y ago
      edit: it's 24k, not 32k, I had the wrong number initially edit2: actually now I'm not so sure, I might have had the right number initially. It's either 24k or 32k. Either way it's impractical. 24,000m/s is the difference in speed that the astronaut is already traveling with the speed necessary to get to the sun Getting to the sun is really hard. Chucking it back into the atmosphere is much easier, but GP was asking about throwing things into the sun.
    - TeMPOraL 6y ago
- JshWright 6y ago
  It takes a "huge" amount of energy to get something to the sun. Something in earth orbit is also orbiting the Sun. The Earth is traveling ~30km/second around the Sun. If you want to fall into the sun, you have to cancel out all that sideways speed.
  - mumblemumble 6y ago
    Another fun thing I didn't really understand all that clearly until I spent time playing KSP: Why it's theoretically easier to get to the Sun from Pluto than it is to do so from here.
    - TeMPOraL 6y ago
      Related: my mind was blown when I realize how easy it is to fall down to Earth (well, Kerbin) if you're in high enough orbit. I've had cases where my orbital velocity was on the order of 200 m/s, which means that at apoapsis you can just fart, and have the satellite crash into the ground a day later. (I've also had my fair share of high-orbit missions where in the middle of the launch I realized I'm aiming for a prograde orbit, where the contract specified retrograde. Instead of reloading game from launchpad, I just carried on, put my apoapsis at target altitude, and once reaching it, burned off couple hundred m/s of Δv to reverse the orbit's direction.)
  - tomc1985 6y ago
    The point isn't really for it to fall into the sun, just to push it to some kind of orbit that is irrelevant to the space junk problem.
    - rocqua 6y ago
      Orbits are periodical. Anything you throw at the sun will come back up to the same height soon enough. (Ignoring smaller effects)
- AngryData 6y ago
  To fall into the sun you would have to negate most of Earth's orbital speed which is about 29.8 kilometers per second. To escape the solar system you need about 42.1 km/s of speed. It actually takes less energy to yeet yourself out of the solar system from Earth than to fall down into the sun. If you threw an object from Earth's orbit along Earth's orbital path an extra 12.3km/s that object would be going 42.1 km/s and eventually but barely leave our solar system. Unfortunately throwing things at kilometers per second by hand is not possible, 1 km/s is just under 2237 mph. Of course with atmospheric drag for most low orbit satellites things will come down eventually, in which case throwing something the right way could add or subtract from the time it will stay in orbit, but that would be highly dependent on where you started. And LEO is already like 7.2 km/s or about 16,000 mph. Standing on a massive enough satellite using a large stick or like a sling staff would certainly help you get more speed in your throw though. A 100 mph baseball throw really wouldn't be that significant though.
lambda_obrien 6y ago
Shoot it with a dart that has a really long wire attached to it, then release the wire to drag in atmosphere, so the satellite is slowly pulled down?
- CompuHacker 6y ago
  You can attach a wire to an object in Earth orbit and use the magnetic field of the Earth to change that object's orbit over time, as well.
  - lambda_obrien 6y ago
    That's an interesting idea, I wonder if you would need a loop or a winding method to get enough counter-emf?
    - morlockabove 6y ago
      There are at least some proposals that use ionised particles in the earth's upper atmosphere as a conductive elements, meaning you don't need a loop as such- just a wire pointing towards the earth with a big metal ball on the end. Lorentz force means you can accelerate prograde or retrograde.
      - lambda_obrien 6y ago
        I find it fascinating to use the natural things you have available as a motive force, and it's really cool to think all you might need is a few bits of conductor and the earth's own relatively static magnetic field to move a satellite around. I wish humans were less interested in the noisy, explosive things like engines and rockets, and more into subtlety.
dredmorbius 6y ago
There are some interesting ways of adding drag to objects. Increasing surface area will (eventually) de-orbit due to drag. The wire methods mentioned earlier could possibly offer the option for magnetic / induction drag. Ion engines are an option, though they're spendy. Geosync orbit is the tough one. It's much larger, but the sweet spots (equatorial orbits) are relatively scarce. Mandating methods of clearing critical orbits (for GEO) or deorbiting (for LEO) implemented prior to deployment is probably the more viable option.
- m4rtink 6y ago
  Thankfully GEO is still a bit self cleaning as Sun and Moon influence makes it unstable - you can clearly see it in orbital debris models, there is a blurry plane shifted ring around the primary GEO stripe. Still that will only prevent a dead sat in sitting in a valuable spot for ever, it migh still drift the wrong way and require active sats to do avoidance maneuvers, not to mention the chance of two inactive sats colliding.
- gmueckl 6y ago
  Self-disposing satellites are a good idea, but it's not perfect. If the control unit or the engines of the satelite fail too early during the satellite's life span, the thing will simply stick around.
  - dredmorbius 6y ago
    Right. And this actually is rocket surgery. There's also the problem of retaining propellants over long periods without experiencing some negative consequence (detonation, unintended firing, volatilisation, etc). But in general, minimising the special-handling cases would be an improvement.
    - TeMPOraL 6y ago
      Long-term propellant issue could probably be solved by using a cold-gas thruster with a non-reactive propellant - basically a pressurized gas tank welded to a valve and a nozzle. It should have enough Δv to push you into a graveyard orbit, or even deorbit straight from GEO (though that's probably dangerous, and I imagine you could see spectacular fireworks from the ground, as the satellite would be hitting the atmosphere with a couple km/s more velocity than it's typical).
TeMPOraL 6y ago
> Assuming you manage to grab a hold of debris without ripping off even tiny parts There are some ideas that could be repurposed from asteroid mining concepts. Many asteroids are more like pile of gravel loosely bound by gravity than solid rocks, and either way, trying to extract anything risk launching lots of tiny pebbles in a random directions. One idea I saw floating around NASA website was to wrap such an asteroid in a net or sheet of material, to keep it from shaking itself apart. I could imagine similar lightweight net being used to wrap a satellite. Once wrapped, you can do two things with it. You can try to deorbit captured trash - for instance, with a light net and a solar sail attached (which would be used to increase atmospheric drag). Such trash would not only deorbit faster, but a sail would make it easier to track. Nets and sails would have to be light and disposable, they could be shipped to orbit in bulk, or (later) manufactured in space. Alternatively, you can try to recycle the trash. If you have in-orbit refueling using propellant sourced from space, you probably already have - or are about to have - some facility in orbit that could reprocess parts of dead satellites. So you can move the trash to some designated recycling orbit. -- Now that I think of it, you could probably make a recycling collector work without all the infrastructure in space. In orbit, you have time, you can take things slow. I can imagine a collector chasing light trash using ion thrusters, or whatever is most promising in high-Isp department these days (how small can a VASIMR get anyway?), grabbing it and parking at the recycling orbit. Might take weeks per piece of trash, but if you launch a bunch of such collectors and feed them trajectories from the ground, they'll eventually clean the orbit out of light trash. It might require some actual developments in the beamed power department, and perhaps launching a power satellite to microwave some electricity to the collectors, but think it would work in (sufficiently modded) KSP :). Anyway, the biggest problem isn't mission design, but figuring out who will actually pay for this. Not sure what to do about the most dangerous space trash - the tiny bits that can't be reliably tracked. Track them better and vaporize with lasers?
- morlockabove 6y ago
  'Laser brooms' are one idea. I think you still have to be able to resolve the debris, but the idea is to end up causing assymetric light-induced thrust on the debris, deorbiting it faster (by heating the prograde side). Another very 'interesting' idea is deploying a large amount of fine dust on an appropriate polar orbit. Everything intersecting that orbit will be sandblasted, increasing drag; this will have the greatest effect on the smallest debris, and hopefully anything operational in that orbit will be well enough armored or able to dodge the cloud. The dust deorbits quickly for the same reason as the tiny debris (greater surface area/volume). One of the more metal ideas for space debros handling I've heard.
sigstoat 6y ago
> Assuming you manage to grab a hold of debris without ripping off even tiny parts, how would you dispose of it? You'd need to deorbit it and you need a working engine for that. meet up with the debris, reorient yourself and the debris such that the debris is closer to the earth (reaction wheels, magnetic torquer bar and patience is all that's required), and then just mechanically kick it down (store up energy from the sun and then trigger a solenoid). the debris itself becomes your propulsion. you get a tiny boost up, perhaps towards your next target, and it gets a (admittedly!) tiny boost down. obviously it doesn't instantly dispose of everything, but progressively pushing material further down the gravity well is the next best thing. not claiming this would be cost effective.
- ramses0 6y ago
  Clever! A 'hopper' bot. Capacitor + Discardable Mass == Thrust.
- Denvercoder9 6y ago
  > then just mechanically kick it down (store up energy from the sun and then trigger a solenoid). the debris itself becomes your propulsion. you get a tiny boost up, perhaps towards your next target, and it gets a (admittedly!) tiny boost down This doesn't actually work. If you push something down in orbit, you just make its orbit elliptical. After half an orbit it will be at the same altitude as you again, and after a full orbit it will hit you from the top. If you want to lower its orbit, you need to push it back. Orbital mechanics is weird.
  - craftinator 6y ago
    > This doesn't actually work. If you push something down in orbit, you just make its orbit elliptical. Came here to say this as well! The only caveat to that I can think of is if you're already low enough in orbit, the push making the satellite's orbit elliptical could put it in a drag zone, and then air would do the slowing down for you. Also, thank you Neal Stephenson for introducing me to the wonderful would of orbital mechanics via Seveneves!
m4rtink 6y ago
You could attach a simple lightweight drag sail or a Echo style very low pressure balloon. That can increase drag of the thing by orders of magnitude and get it down fast while you tug goes for the next target or returns for refueling or restocking.
SyzygistSix 6y ago
Why does it need to be deorbited? Why is collected and held not effective?

tomc1985 6y ago

Could an astronaut grab a smaller satellite and simply chuck it towards the sun? Would it have enough velocity break out of earth orbit or would it just get stuck in some really large, wide, graveyard orbit? If not the sun then maybe the earth? That would be a fun spacewalk.

DavidSJ 6y ago
The ∆v to escape Earth orbit is generally quite large, and it's far, far greater still to collide with the Sun (though this wouldn't normally be considered necessary). In comparison, a deorbit burn is usually relatively inexpensive.
deleted 6y ago
[deleted]
taejo 6y ago
From low Earth orbit, delta-v to Earth and to escape the solar system are about the same. Delta-v to fall into the sun is two orders of magnitude bigger.
- labawi 6y ago
  Directly. Not if you take it the long way - near escape to reduce orbital speed, a little push to cancel the rest, and you will fall directly into the Sun (with a high velocity).
dmoy 6y ago
It would be difficult for an astronaut to chuck an object with over 32,000m/s of delta-v. For comparison, the fastest bullets go like ~1,500m/s, and they are very very very small.
- darkwizard42 6y ago
  I think the goal would be to first accelerate the astronaut to that level of velocity and then relatively adjusting its trajectory isn't so difficult. But, that is just my understanding that speed is relative (especially in space with no drag)
  - morlockabove 6y ago
    Speed is also extremely expensive due to the rocket equation- changing your velocity, that is.
  - dmoy 6y ago
    It would surely be easier to accelerate space trash into the sun than it would be to accelerate both the astronaut and space trash into the sun. I don't think we should do either of those, but less mass is always easier to speed up.
- tomc1985 6y ago
  If I chuck a baseball out of an airplane I don't have to worry about accelerating the baseball to the airplane's speed, as I am also traveling at that speed. Similarly, if a satellite is light enough in low-G to grab and manipulate from a craft that has straddled up along side it, would a single astronaut have enough strength to use his arms to put a satellite on a path that is effectively out of the way? Or could they just chuck it back at the earth so it can burn up on reentry?
  - dmoy 6y ago
    edit: it's 24k, not 32k, I had the wrong number initially edit2: actually now I'm not so sure, I might have had the right number initially. It's either 24k or 32k. Either way it's impractical. 24,000m/s is the difference in speed that the astronaut is already traveling with the speed necessary to get to the sun Getting to the sun is really hard. Chucking it back into the atmosphere is much easier, but GP was asking about throwing things into the sun.
  - TeMPOraL 6y ago
JshWright 6y ago
It takes a "huge" amount of energy to get something to the sun. Something in earth orbit is also orbiting the Sun. The Earth is traveling ~30km/second around the Sun. If you want to fall into the sun, you have to cancel out all that sideways speed.
- mumblemumble 6y ago
  Another fun thing I didn't really understand all that clearly until I spent time playing KSP: Why it's theoretically easier to get to the Sun from Pluto than it is to do so from here.
  - TeMPOraL 6y ago
    Related: my mind was blown when I realize how easy it is to fall down to Earth (well, Kerbin) if you're in high enough orbit. I've had cases where my orbital velocity was on the order of 200 m/s, which means that at apoapsis you can just fart, and have the satellite crash into the ground a day later. (I've also had my fair share of high-orbit missions where in the middle of the launch I realized I'm aiming for a prograde orbit, where the contract specified retrograde. Instead of reloading game from launchpad, I just carried on, put my apoapsis at target altitude, and once reaching it, burned off couple hundred m/s of Δv to reverse the orbit's direction.)
- tomc1985 6y ago
  The point isn't really for it to fall into the sun, just to push it to some kind of orbit that is irrelevant to the space junk problem.
  - rocqua 6y ago
    Orbits are periodical. Anything you throw at the sun will come back up to the same height soon enough. (Ignoring smaller effects)
AngryData 6y ago
To fall into the sun you would have to negate most of Earth's orbital speed which is about 29.8 kilometers per second. To escape the solar system you need about 42.1 km/s of speed. It actually takes less energy to yeet yourself out of the solar system from Earth than to fall down into the sun. If you threw an object from Earth's orbit along Earth's orbital path an extra 12.3km/s that object would be going 42.1 km/s and eventually but barely leave our solar system. Unfortunately throwing things at kilometers per second by hand is not possible, 1 km/s is just under 2237 mph. Of course with atmospheric drag for most low orbit satellites things will come down eventually, in which case throwing something the right way could add or subtract from the time it will stay in orbit, but that would be highly dependent on where you started. And LEO is already like 7.2 km/s or about 16,000 mph. Standing on a massive enough satellite using a large stick or like a sling staff would certainly help you get more speed in your throw though. A 100 mph baseball throw really wouldn't be that significant though.

lambda_obrien 6y ago

Shoot it with a dart that has a really long wire attached to it, then release the wire to drag in atmosphere, so the satellite is slowly pulled down?

CompuHacker 6y ago
You can attach a wire to an object in Earth orbit and use the magnetic field of the Earth to change that object's orbit over time, as well.
- lambda_obrien 6y ago
  That's an interesting idea, I wonder if you would need a loop or a winding method to get enough counter-emf?
  - morlockabove 6y ago
    There are at least some proposals that use ionised particles in the earth's upper atmosphere as a conductive elements, meaning you don't need a loop as such- just a wire pointing towards the earth with a big metal ball on the end. Lorentz force means you can accelerate prograde or retrograde.
    - lambda_obrien 6y ago
      I find it fascinating to use the natural things you have available as a motive force, and it's really cool to think all you might need is a few bits of conductor and the earth's own relatively static magnetic field to move a satellite around. I wish humans were less interested in the noisy, explosive things like engines and rockets, and more into subtlety.

dredmorbius 6y ago

There are some interesting ways of adding drag to objects. Increasing surface area will (eventually) de-orbit due to drag. The wire methods mentioned earlier could possibly offer the option for magnetic / induction drag. Ion engines are an option, though they're spendy. Geosync orbit is the tough one. It's much larger, but the sweet spots (equatorial orbits) are relatively scarce. Mandating methods of clearing critical orbits (for GEO) or deorbiting (for LEO) implemented prior to deployment is probably the more viable option.

m4rtink 6y ago
Thankfully GEO is still a bit self cleaning as Sun and Moon influence makes it unstable - you can clearly see it in orbital debris models, there is a blurry plane shifted ring around the primary GEO stripe. Still that will only prevent a dead sat in sitting in a valuable spot for ever, it migh still drift the wrong way and require active sats to do avoidance maneuvers, not to mention the chance of two inactive sats colliding.
gmueckl 6y ago
Self-disposing satellites are a good idea, but it's not perfect. If the control unit or the engines of the satelite fail too early during the satellite's life span, the thing will simply stick around.
- dredmorbius 6y ago
  Right. And this actually is rocket surgery. There's also the problem of retaining propellants over long periods without experiencing some negative consequence (detonation, unintended firing, volatilisation, etc). But in general, minimising the special-handling cases would be an improvement.
  - TeMPOraL 6y ago
    Long-term propellant issue could probably be solved by using a cold-gas thruster with a non-reactive propellant - basically a pressurized gas tank welded to a valve and a nozzle. It should have enough Δv to push you into a graveyard orbit, or even deorbit straight from GEO (though that's probably dangerous, and I imagine you could see spectacular fireworks from the ground, as the satellite would be hitting the atmosphere with a couple km/s more velocity than it's typical).

TeMPOraL 6y ago

> Assuming you manage to grab a hold of debris without ripping off even tiny parts There are some ideas that could be repurposed from asteroid mining concepts. Many asteroids are more like pile of gravel loosely bound by gravity than solid rocks, and either way, trying to extract anything risk launching lots of tiny pebbles in a random directions. One idea I saw floating around NASA website was to wrap such an asteroid in a net or sheet of material, to keep it from shaking itself apart. I could imagine similar lightweight net being used to wrap a satellite. Once wrapped, you can do two things with it. You can try to deorbit captured trash - for instance, with a light net and a solar sail attached (which would be used to increase atmospheric drag). Such trash would not only deorbit faster, but a sail would make it easier to track. Nets and sails would have to be light and disposable, they could be shipped to orbit in bulk, or (later) manufactured in space. Alternatively, you can try to recycle the trash. If you have in-orbit refueling using propellant sourced from space, you probably already have - or are about to have - some facility in orbit that could reprocess parts of dead satellites. So you can move the trash to some designated recycling orbit. -- Now that I think of it, you could probably make a recycling collector work without all the infrastructure in space. In orbit, you have time, you can take things slow. I can imagine a collector chasing light trash using ion thrusters, or whatever is most promising in high-Isp department these days (how small can a VASIMR get anyway?), grabbing it and parking at the recycling orbit. Might take weeks per piece of trash, but if you launch a bunch of such collectors and feed them trajectories from the ground, they'll eventually clean the orbit out of light trash. It might require some actual developments in the beamed power department, and perhaps launching a power satellite to microwave some electricity to the collectors, but think it would work in (sufficiently modded) KSP :). Anyway, the biggest problem isn't mission design, but figuring out who will actually pay for this. Not sure what to do about the most dangerous space trash - the tiny bits that can't be reliably tracked. Track them better and vaporize with lasers?

morlockabove 6y ago
'Laser brooms' are one idea. I think you still have to be able to resolve the debris, but the idea is to end up causing assymetric light-induced thrust on the debris, deorbiting it faster (by heating the prograde side). Another very 'interesting' idea is deploying a large amount of fine dust on an appropriate polar orbit. Everything intersecting that orbit will be sandblasted, increasing drag; this will have the greatest effect on the smallest debris, and hopefully anything operational in that orbit will be well enough armored or able to dodge the cloud. The dust deorbits quickly for the same reason as the tiny debris (greater surface area/volume). One of the more metal ideas for space debros handling I've heard.

sigstoat 6y ago

> Assuming you manage to grab a hold of debris without ripping off even tiny parts, how would you dispose of it? You'd need to deorbit it and you need a working engine for that. meet up with the debris, reorient yourself and the debris such that the debris is closer to the earth (reaction wheels, magnetic torquer bar and patience is all that's required), and then just mechanically kick it down (store up energy from the sun and then trigger a solenoid). the debris itself becomes your propulsion. you get a tiny boost up, perhaps towards your next target, and it gets a (admittedly!) tiny boost down. obviously it doesn't instantly dispose of everything, but progressively pushing material further down the gravity well is the next best thing. not claiming this would be cost effective.

ramses0 6y ago
Clever! A 'hopper' bot. Capacitor + Discardable Mass == Thrust.
Denvercoder9 6y ago
> then just mechanically kick it down (store up energy from the sun and then trigger a solenoid). the debris itself becomes your propulsion. you get a tiny boost up, perhaps towards your next target, and it gets a (admittedly!) tiny boost down This doesn't actually work. If you push something down in orbit, you just make its orbit elliptical. After half an orbit it will be at the same altitude as you again, and after a full orbit it will hit you from the top. If you want to lower its orbit, you need to push it back. Orbital mechanics is weird.
- craftinator 6y ago
  > This doesn't actually work. If you push something down in orbit, you just make its orbit elliptical. Came here to say this as well! The only caveat to that I can think of is if you're already low enough in orbit, the push making the satellite's orbit elliptical could put it in a drag zone, and then air would do the slowing down for you. Also, thank you Neal Stephenson for introducing me to the wonderful would of orbital mechanics via Seveneves!

m4rtink 6y ago

You could attach a simple lightweight drag sail or a Echo style very low pressure balloon. That can increase drag of the thing by orders of magnitude and get it down fast while you tug goes for the next target or returns for refueling or restocking.

SyzygistSix 6y ago

Why does it need to be deorbited? Why is collected and held not effective?