What happens to small pieces of debris left floating around inside a derelict space station?

My space station had 100 people aboard, and due to sabotage, it decompressed and was abandoned. Inside, there are thousands of small items, like screws, papers, tools, usb memory sticks, forks, and so on.

Movies usually show these hanging around in the air, but what would really happen to them over years and decades? Would any kind of rotation of the station produce centrifigual forces that would move all the debris to the walls? Would static charges cause them to clump together? Would frictional losses from collisions mean everything comes to rest randomly distributed against the walls?

When the atmosphere was lost, it happened reasonably slowly by an irreversible evacuation of the air through the main air circulation system until it reached total vacuum. My scenario has no artificial gravity, so items would usually be secured, but the evacuation occurred during a riot and there were minor explosions, damage, and panic so it was quite messy inside.

50 years later I wonder what the inside looks like. Obviously I'm looking for realistic plausible answers here.

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    $\begingroup$ Station abandoned for 50 years in space would probably got destroyed by meteoroids or debris of other stations/satellites, unless it is on low earth orbit in which case it would just fall into atmosphere, or has avoidance mechanisms and engines still functional. $\endgroup$ – jaboja Aug 10 '17 at 20:45
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    $\begingroup$ @Jakub Jagiełło - we have satellites on higher orbits for decades, they are slowly decaying, but not getting "destroyed". $\endgroup$ – Alexander Aug 10 '17 at 20:50
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    $\begingroup$ It's in a high orbit, free from atmospheric drag. Micrometeor impacts may cause it to tumble gently, but do not otherwise damage it $\endgroup$ – Innovine Aug 10 '17 at 20:53

Things would slowly clump together or come to rest near a wall. Anything moving slowly will hit a wall or hit another object.

Unless the walls and objects are hard sided (like pool balls), they will lose more than a little energy every time they hit something. Eventually, the object will lose the energy to move after a collision. This will place them near something.

If passages are narrow, that location will likely be a wall. If it is a wide open space, there will likely be several clumps.

Also, any hits against the station will move the station faster than they move the objects inside it. I don't know for certain but I believe that a station with a wide cross section will face fairly random accelerations from micro impacts. Also, solar winds will cause regular accelerations. the accelerations will not be from a constant direction (unless solar tracking is still active in the solar panels). This will produce a cycle of accelerations that may bias the movement of objects in the station.

  • $\begingroup$ But won't SOME kinetic energy always remain after a collision? Even if it is tiny, this is enough to bounce an object back at a tiny, tiny velocity so you might find it floating free 50 years later...? For the clumps, what force do you think causes them to clump? I will have to think about micro impacts and solar winds. This is a real factor in my scenario, although i haven't considered it deeply yet. If the station was rotating slowly, and periodically passed through some dust clouds, this would decelerate it slightly, but different directions each time. Enough to keep stirring the contents? $\endgroup$ – Innovine Aug 11 '17 at 8:29
  • $\begingroup$ @Innovine, see Karl's answer. He makes that point much better that I did. $\endgroup$ – ShadoCat Aug 11 '17 at 17:14

The inelastic part in any collision (call it friction, if you like) will decelerate any moving object in a very short time (hours or days, maximum). Below a certain collision speed, objects will stick to the walls due to van der Waals forces.

  • $\begingroup$ Can you speculate on whether these forces are strong enough to resist the accelerations caused by the station passing through dust, or being hit by a small meteor? $\endgroup$ – Innovine Aug 11 '17 at 8:33
  • $\begingroup$ @Innovine No. That would depend on the actual contact area (sourface roughness) and materials, and on the density and relative velocity of said dust. Very tricky to relate that to reality. $\endgroup$ – Karl Aug 11 '17 at 18:20

It depends on the motion, if any, of the station after it's abandoned; it won't take long before momentum loses in collisions will get all the objects moving in more or less the same direction and relatively "at rest", mostly on the walls but with some material in midair too. However once you get any new motion, say the "bump" from a docking salvage ship the equilibrium is broken and everything is thrown around afresh and could end up anywhere.

That assumes the station wasn't spinning at all, otherwise everything ends up on the "floor", that being the areas farthest from the axis of rotation. Even a very little spin caused by uncorrected recoil from evacuation ships would shift things slowly outwards over time. Again a salvage vessel docking will upset the settled material, especially if it corrects the spin in the process of docking.

Water is going to be an interesting factor, if enough of it is thrown around in the panic, either from burst pipes or as blood, it may well seal the hull when it freezes and freeze areas of material into solid rock-hard dirty ice chunks as well as allow you to have frozen atmosphere that didn't escape leaving patches of frozen oxygen etc... that will sublime on contact with anything above about 90 Kelvin.

Depending how long it takes to evacuate and freeze down once people leave and power fails you're looking at rotten stores as well as the potential blood and gore. That's going to leave shall we say organic stains in many areas.

  • $\begingroup$ I assume micrometeorites will impart some spin onto the station ... $\endgroup$ – Innovine Sep 5 '17 at 8:08
  • $\begingroup$ @Innovine Possible but unlikely, you probably won't see sufficiently directional impacts, micro-meteors will generally come from all directs, any impact that holes the hull while there's still gas-phase atmosphere on board will induce spin from the exhaust. $\endgroup$ – Ash Sep 5 '17 at 11:29
  • $\begingroup$ Not sure i agree.... first, all impacts will exert an acceleration, and all but directly on the CoM will cause a rotation. Micrometeories are unlikely to come from the side of the planet the station is orbiting, and more likely to come from the prograde direction as the station moves into them. $\endgroup$ – Innovine Sep 5 '17 at 11:36
  • $\begingroup$ @Innovine Sure the net motion will be towards the planet but extra-orbital debris are tiny and are going to come in from any other direction. You might get some spin if you had a lot of impacts from one direction for some reason but most of the momentum will be absorbed materially not imparting much kinetic energy at all. $\endgroup$ – Ash Sep 5 '17 at 11:43

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