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Small space debris is a serious problem. I think that if a large container orbits full of space debris and sweeps up small pieces of space debris that fit into the container, the space debris can be cleaned up cleanly. Why is this method not used in practice? In what ways is it limited and in what ways is it inefficient?

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    $\begingroup$ It's like catching flying bullets with a dust pan. $\endgroup$
    – Alexander
    Commented Feb 11 at 3:40
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    $\begingroup$ In addition to the problems already stated in answers, there is the additional challenge of sweeping space debris without sweeping spacecrafts and satellites. $\endgroup$
    – Pere
    Commented Feb 11 at 12:27
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    $\begingroup$ This is analogous to using nets to catch fish in the ocean, except the fish are moving at thousands of kilometers per hour and also the fish are all hundreds or thousands of kilometers away from each other. You need either an absolutely enormous net or you need to make an enormous number of passes, catching only a tiny number of fish per pass. $\endgroup$
    – chepner
    Commented Feb 11 at 16:50
  • $\begingroup$ @Alexander or birdshot, because there are a lot of them and all spread out.. $\endgroup$
    – Conrado
    Commented Feb 12 at 16:11
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    $\begingroup$ Why is this question attracting downvotes? $\endgroup$
    – gerrit
    Commented Feb 13 at 8:00

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The problem is that every bit of space debris is in its own orbit. If you want to match that orbit, it takes a lot of fuel. If you don't do that, and you just intercept it, you will find that the debris is flying at a high speed (several km/s) compared to you. This means the debris will punch a hole through your container, like a bullet, instead of being caught.

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    $\begingroup$ “Space is big. Really big…” which is a whole other problem as well… $\endgroup$
    – Jon Custer
    Commented Feb 10 at 17:09
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    $\begingroup$ "This means the debris will punch a hole through your container" … and create an additional order of magnitude of orbital shrapnel in the process. $\endgroup$ Commented Feb 11 at 10:57
  • $\begingroup$ @JörgWMittag: Depending upon the masses, velocities, and construction of the objects involved, I would think a collision could impart a substantial radial component of velocity; small objects with eccentric orbits whose perigee is below the top of the atmosphere won't remain dangerous for very long. $\endgroup$
    – supercat
    Commented Feb 12 at 21:48
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    $\begingroup$ Actually it's misleading to say it would punch a hole like a bullet would. The debris is much faster than a bullet, which makes for some important differences: when it hits the container, both the debris and the spot it hit instantly vapourize. That's kind of a good thing because this vapour itself would eventually disperse harmlessly, the problem is that it first expands explosively which generally means a whole lot of fresh debris is ripped out of the container, with the result that you have a lot more space debris orbit after the collisions than before. $\endgroup$ Commented Feb 15 at 22:26
  • $\begingroup$ ...One solution would be to make the container out of ice: the shards would then automatically sublimate and effectively vanish from orbit. $\endgroup$ Commented Feb 15 at 22:28
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Sweeping up space debris in orbit is a bit like sweeping up bullets in mid-air in the middle of a machine-gun fight, except the debris is probably moving faster (relative to the sweeper) than the bullets.

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    $\begingroup$ i.sstatic.net/Zd3fj.png $\endgroup$
    – uhoh
    Commented Feb 12 at 2:05
  • $\begingroup$ The debris is also farther apart than the bullets. $\endgroup$
    – gerrit
    Commented Feb 13 at 7:59
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    $\begingroup$ It's a bit more like protecting Elephants, and Rhino's, and polar bears, and penguins, and several other species, by employing just one man with a single small bullet-proof shield. $\endgroup$
    – MikeB
    Commented Feb 13 at 9:38
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From a diplomatic perspective: you say space debris cleanup, I hear anti-satellite weapon.

If you announce you have the capability to do this, you are going to attract the attention of all the major spacefaring powers, who have invested heavily in their satellites and rely on them for both civilian and military purposes. If you are one of them, you risk starting an arms race and accelerating the militarisation of space.

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    $\begingroup$ the major spacefaring powers have anti-satellite weapons already. Two of them also had vehicles obviously designed with stealing satellites in mind, but only one of them used that vehicle operationally and mostly used it to build a space station $\endgroup$
    – Erin Anne
    Commented Feb 11 at 23:44
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    $\begingroup$ @ErinAnne slightly related: Was the Space Shuttle ever actually intended for the military to steal satellites without the owner's consent? $\endgroup$
    – uhoh
    Commented Feb 12 at 1:52
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    $\begingroup$ I think the capability of catching small debris without being destroyed might be something different than catching a whole satellite. And yet another thing than just destroying that satellite (which actually sounds easier). $\endgroup$ Commented Feb 13 at 2:17

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