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Trash Disposal: Or: when and why they realized they cannot just throw it out of airlock


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While trying to rebuild my Skylab analogue (with an eye toward some ETS stuff), a question that I have is the issue of Trash disposal. Specifically, they used the oxygen tank for trash disposal, as they didn't have any plan for resupply, which in turn allows disposing of trash (In ETS canon, NASA developed a cargo spacecraft, thus freeing up the Oxygen tank as extra pressurized volume)

So aside from basic physics which affect the orbiting craft's trajectory, what other things made them realize it's a bad idea to throw trash out into the Orbit? To my understanding, Kessler Syndrome theory is not developed until 1978.

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To my knowledge there was a period of time the Salyuts cast junk overboard.

Wrapped in tinfoil.

Which caused it to show up as UFOs during subsequent orbits!

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My guess is that it has a lot to do with the fact that opening an airlock isn't that trivial as it sounds. Well, at least not if you want to continue living a long time afterwards. ;) AFAIK just getting into a spacesuit, making sure that it works, pumping down the airlock space, and then reversing the whole process is a major undertaking. And something that you probably don't really want to do surrounded by piles of trash if you can help it. You also loose some air every time that you do that.

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Just btw. The last Dragon has brought to ISS such a nice thing.

https://en.wikipedia.org/wiki/Nanoracks_Bishop_Airlock

https://directory.eoportal.org/web/eoportal/satellite-missions/content/-/article/iss-utilisation-nanoracks-airlock

Now they can throw their rubbish in higher orbit or down.

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Almaz had a ~90 cm wide film capsule launch tube which also could be used for dejunking.

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Also we should remember that Skylab was a rather simplified design compared to the "wet lab" and 50-men crew projects. Actually, a proof of concept.

Its later Venusian fly-by version also didn't need a junk removal, being single-use.

Edited by kerbiloid
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Opening an airlock is not as trivial as it sounds. Plus, you have to make sure that your trash end up in a sufficiently different orbit as so not to smack in front of your face immediately afterwards (well, 1 orbital revolution). You can't just slowly separate it off, you have to shoot it out.

41 minutes ago, kerbiloid said:

Now they can throw their rubbish in higher orbit or down.

Don't you generally want to throw your trash to a lower orbit ? It will then deorbit on itself.

 

But yeah, at least in near-Earth space, we've always deorbited our space trash in one way or another. Problem arise when it's simply too high for residual drag to take it's course... so MEO and GSO/HEO. Further than this I think our only objection has been on Planetary Protection (so crashing things to Mars and certain gas giant moons).

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From a Scott Manley video, you only need about 100mph (160km/h) delta-v to deorbit trash (presumably for trash that will burn up.  Hitting the satellite burial grounds in the Pacific likely requires more precision).  So a small pneumatic cannon should do the trick.

Note: it might be a bit more than that.  The answer was that you couldn't throw something fast enough (absolute top professional baseball pitchers could hit that range, but not in a space suit), could easily reach that velocity with a golf club and ball (although the space suit might make it problematic.  And Alan Shepard (holder of the beyond-the-world record golf shot of 515 yards)  is no longer with us to describe the difficulties of non-Earth golfing.  I think the best answer was to put the trash in a ball and use a  jai-alai "glove" to throw it.  But it wouldn't require your pneumatic cannon to hit any significant "delta-v" (at least significant to a rocket scientist.  Cannon makers used to shooting out t-shirts might have to scale up their designs).

For such limited missions, I'd expect "put it in a bag and stick it to the outside" would be an option.  But that would require and additional expensive airlock and probably make full spacesuits essential.  So I'm not surprised it isn't an option (but might be considered for a Mars orbiting gateway).

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25 minutes ago, wumpus said:

From a Scott Manley video, you only need about 100mph (160km/h) delta-v to deorbit trash (presumably for trash that will burn up.  Hitting the satellite burial grounds in the Pacific likely requires more precision).  So a small pneumatic cannon should do the trick.

Note: it might be a bit more than that.  The answer was that you couldn't throw something fast enough (absolute top professional baseball pitchers could hit that range, but not in a space suit), could easily reach that velocity with a golf club and ball (although the space suit might make it problematic.  And Alan Shepard (holder of the beyond-the-world record golf shot of 515 yards)  is no longer with us to describe the difficulties of non-Earth golfing.  I think the best answer was to put the trash in a ball and use a  jai-alai "glove" to throw it.  But it wouldn't require your pneumatic cannon to hit any significant "delta-v" (at least significant to a rocket scientist.  Cannon makers used to shooting out t-shirts might have to scale up their designs).

For such limited missions, I'd expect "put it in a bag and stick it to the outside" would be an option.  But that would require and additional expensive airlock and probably make full spacesuits essential.  So I'm not surprised it isn't an option (but might be considered for a Mars orbiting gateway).

Yes, for later space stations like Mir and ISS they get resuply missions and you simply stuff the trash in the return module. All outside dragon and the shuttle burned up anyway.  Manned Soyuz return module is too cramped to bring back much anyway so dragon 1 was welcome for return samples. As garbage tend to be smaller than the original or at least have voids you can stuff trash in its no volume issues, you can also vacuum seal smelly stuff. 

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It's no need in small trash bags, as any envelope should be delivered to LEO and deorbited, so a single-use cargo ship is what they need.

A reusable propulsion/docking unit could be, with expendable cargo compartment.

Edited by kerbiloid
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9 minutes ago, kerbiloid said:

a single-use cargo ship is what they need.

We have Cygnus as well as Progress (at least the non-return variant, I know there exist return variants - for those the orbital module would still be burned away). Also chucking it in Dragon trunk is an option, as well as Soyuz orbital module.

12 hours ago, wumpus said:

From a Scott Manley video, you only need about 100mph (160km/h) delta-v to deorbit trash (presumably for trash that will burn up. 

I think lowering it down to a sufficiently low perigee would work as well. Wouldn't deorbit immediately after one revolution, but within a few orbits (maybe even a day) should be fine...

Edited by YNM
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2 minutes ago, YNM said:

We have Cygnus as well as Progress (at least the non-return variant, I know there exist return variants - for those the orbital module would still be burned away). Also chucking it in Dragon trunk is an option, as well as Soyuz orbital module.

Yes, though unlike Cygnus, Progress, and Soyuz, the Dragon trunk needs Canadarm manipulations and some berthable rack. In C, P, S you just put your bags inside.

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7 hours ago, YNM said:

I know there exist return variants

Not really. They have a bag-sized return canister in a spring-loaded launcher on the outside of their docking hatch.

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21 hours ago, YNM said:

We have Cygnus as well as Progress (at least the non-return variant, I know there exist return variants - for those the orbital module would still be burned away). Also chucking it in Dragon trunk is an option, as well as Soyuz orbital module.

I think lowering it down to a sufficiently low perigee would work as well. Wouldn't deorbit immediately after one revolution, but within a few orbits (maybe even a day) should be fine...

I'm pretty sure that's how the 100mph delta-v de-orbit works.   Of course *all* instantaneous delta-v reductions are about reducing the perigee, and 100mph is barely noticeable (presumably *just* hits the atmosphere).  The "de-orbiting velocity" he talks about isn't about lowering perigee down to sea level.

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