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During one of the most iconic scenes of A New Hope, the protagonists end up in a trash compactor.

Why does the Death Star have one? Why not just blow uncompacted trash into space? And why a mechanical one, when they could also use a directed energy beam to vaporise trash?

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steenbergh
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    Perhaps it doesn't compact the waste for ease of disposal, but for transport. If the waste is recycled, for instance, it might be compacted for ease of transport (weight being less of an issue in space than size). – delinear Feb 22 '18 at 15:46
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    Dump trash into Space which would then orbit around Death Star to screw its weapons, navigation, scanner etc. – user931 Feb 22 '18 at 16:25
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    Although thoroughly Evil™, the Galactic Empire was remarkably progressive when it came to urban recycling and waste reclamation programs—including on their space stations. – Lexible Feb 22 '18 at 17:04
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    I doubt that most space vehicles will just blow trash into space. Why not recycle it instead? In fact that worm thing in the compactor may be part of the recycling system. – Zan Lynx Feb 22 '18 at 18:36
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    @ZanLynx Star Destroyers dump trash in space. Han Solo and Boba Fett take advantage of this in The Empire Strikes Back (Han hiding from the fleet of Star Destroyers, Fett hiding from Han). – 8bittree Feb 22 '18 at 19:04
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    I suppose the narrative answer of "the Death Star needed a trash compactor for the story to work as written" probably won't be a sufficient answer here? –  Feb 23 '18 at 09:32
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    @Zyerah Yes, out-of-universe "because the story needed it to be that way" answers to an implicitly in-universe question are discouraged to the point of being deleted. – Rand al'Thor Feb 24 '18 at 17:47
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    Out-of-universe: the heros couldn't have such an easy escape; they had to face some other perils. In-universe: the Death Star was only just finished; there would have been a whole lot of construction debris to deal with. At the design stage, this would have been taken into account; compactors being an important element in the logistics of waste handling, regardless of its ultimate fate (recycling, dumping into space, etc.). – Anthony X Feb 25 '18 at 23:59
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    It's actually not a trash compactor but a trash juicer, removing the precious water from the dry parts of the trash, which is then dumped. The water is saved for treatment and re-use... Isn't it obvious? – I'm with Monica Feb 26 '18 at 15:46
  • @delinear It's true that weight isn't important, but mass is. Compressing the garbage increases its density, which in turn increases its inertia. Densely compacted garbage would require more fuel to shift, not less. Besides, we know the Star Destroyers dump their rubbish before jumping to lightspeed, why wouldn't the Death Star just do the same? – Tim Feb 27 '18 at 19:32
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    Note that to "dump trash in to space" (or to handle it in any way at all), you first have to organize it and deal with it. You're talking about an absolutely enormous "building", far far larger than any Earth city. Of course it would have many such systems. – Fattie Feb 28 '18 at 11:38

7 Answers7

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The Death Star is 160 km across, or 80 km radius. It is a mixture of air and metal and other substances.

If we assume it is roughly as dense as water (as it looks roughly as dense as a ocean going ship, which is roughly as dense as water), it weighs roughly 2 * 10^18 kg. (If it was solid iron it would be only 8x denser, so this probably isn't off by more than an order of magnitude)

Earth weighs 6 * 10^24 kg and has a roughly 6400 km radius.

Thus the Death Star has a surface gravity of (1/3 * 10^-6)/(80 km / 6400 km)^2, or 0.2% of Earth's gravity. That isn't bad. But it has an escape velocity of roughly 60 meters/second (or 220 km/h or 140 miles/hour).

So if you throw a baseball out into the vacuum, it will fall back and land somewhere else on the death star, even if you are a professional pitcher. At the same time, falling 3 meters will take about 20 seconds, so it will "act like" zero gravity (ignoring any gravity generators).

Simply shoving something out an airlock will result in in falling back towards the death star somewhere else. If you spew vaporized trash out a nozzle, you have to eject it quite fast to prevent the slower particles from falling back on the death star. And nobody wants a death star covered in a thin layer of waste. Ew.

By compacting trash, you can launch it out of the gravity well with far less hassle and mess. And simply getting it to the surface of the death star will be a pain; compacted trash will be easier move around than loose piles.

Remember, vaporized things don't just "go away". That is only true in an environment where the environment picks up your slack and recycles things for you. The Death Star is a constructed environment, and doesn't have an ecosystem to clean up after whatever mess you leave behind (at least, you hope it doesn't). The creature in the compactor might even be there on purpose to digest some of the waste and turn it into something easier to handle, or might be a parasite. At least it isn't rats.

So: Compacted trash is easier to move around (over the 160 km interior). You cannot just open a door and throw the trash out into vacuum -- you have to launch it, either in a special purpose accelerator or in a special purpose garbage scow.

In both such cases, compact trash that doesn't fall apart is going to be easier to work with, and easier to temporary store, than either hot non-uniform plasma/gas or random piles of garbage.

Davidw
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Yakk
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    I like the analysis of the Death Star's escape velocity, but how does compacting the trash fix that problem? – Nuclear Hoagie Feb 22 '18 at 21:13
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    @NuclearWang If you compact the trash into a dense cube that almost perfectly fits a gas-based launcher, it will be accelerated more efficiently. If they use something like a magnetic railgun, they would need to make sure the trash was compacted with a certain percentage of magnetic metal. To avoid the gravity problem altogether, they may ship the trash using a smaller ship that escapes the gravity well on its own - in that case, having it in cubes is easier to pack in the transport. – IllusiveBrian Feb 22 '18 at 21:58
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    "...and doesn't have an ecosystem..." Well, the trash compactor kind of was one... – jpmc26 Feb 23 '18 at 03:42
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    an excellent, well thought out answer. +1. I'd also add that for the destroyers just jettisoning trash into space, they're not hanging about to bump into this stuff, whilst a space station (even one that can be moved) is still in the general area for this stuff to come back and hit it. – Miller86 Feb 23 '18 at 11:06
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    @Miller86 it’s specifically mentioned that dropping the garbage when leaving a place, i.e. going to accelerate away from it, is a standard procedure for the destroyers. Whether a “standard procedure” existed for the Death Star, is not clear, as it was the first of its kind. – Holger Feb 23 '18 at 11:47
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    "And nobody wants a death star covered in a thin layer of waste." - Well, it would probably look more like a moon, after some decades. Great answer, however. – Dubu Feb 23 '18 at 15:36
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    Additionally, compacting the trash makes it easier to store so you can eject it in an appropriate location. It'd be a shame to fill the orbit of a planet like, say, Alderaan, with space junk. – SethWhite Feb 23 '18 at 17:06
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    @NuclearWang - Try this experiment: Try to throw a handful of paper shreds. Each piece doesn't go very far, does it? Next, crumple up a piece of paper and throw it. Much easier to throw it further, isn't it? Not quite an equivalent comparison because [insert physics here] but the veeeeery general principles are kinda the same. – Broots Waymb Feb 23 '18 at 21:52
  • The escape velocity is smaller when near a larger mass. So launch onto the planet you’re about to destroy. If there’s not a target when you need to dump, launch it into a large star. – WGroleau Feb 23 '18 at 23:18
  • None of these answers explains why there is a snake in the trash compactor :( – astroanu Feb 24 '18 at 08:34
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    "[An] ocean going ship, which is roughly as dense as water": this describes the iceberg, not the Titanic. A fully loaded oil tanker will be mostly under water, but as you can see from the plans of actual ships (e.g. https://upload.wikimedia.org/wikipedia/commons/e/eb/HMS_Dreadnought_%281911%29_profile_drawing.png), even a heavily-armored dreadnought had about half its volume, maybe more, above the waterline. So the gravity well of the Death Star is probably not nearly as "deep" as you calculate, though (I think) it is still enough to justify this answer. – David K Feb 24 '18 at 20:06
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    Maybe the next movie will have an even bigger even bigger Death Star whose superweapon is launching compacted trash at planets. – xdhmoore Feb 25 '18 at 01:51
  • Why not throw all the trash in a bucket and then wait until the next firing and just chuck the trash into the laser cannon while its firing? – NL628 Feb 25 '18 at 07:03
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    @nl628 because trash converted to high energy subatomic slurry is a bigger problem than trash? – Yakk Feb 25 '18 at 08:55
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    @jpmc26 New Canon has established that the Dianoga inside the trash compactor was not native to that trash compactor, but was instead an alien creature that ended up there: http://starwars.wikia.com/wiki/Omi – pepoluan Feb 25 '18 at 13:24
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    @astroanu See: http://starwars.wikia.com/wiki/Omi – pepoluan Feb 25 '18 at 13:24
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    @BrootsWaymb The very general principles of that example don't apply at all in space. All you're illustrating there is the concept of air resistance and terminal velocity, which is completely irrelevant in a vacuum. Try this experiment: try to throw a 10-pound stone, then try to throw ten 1-pound stones. You can throw the lighter stone more easily, right? Thought experiments don't mean much unless they're representative of the system you're reasoning about. – Nuclear Hoagie Feb 25 '18 at 21:07
  • Great effort. Ate this up with a spoon – Jason P Sallinger Feb 26 '18 at 00:54
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    @Holger I imagine the death star was designed to stay in the same place for a while since part of the defensive strategy involved a shield generator on the forest moon of Endor, rather than just relying on deflector shields from within the structure itself. – martin Feb 26 '18 at 02:36
  • @NuclearWang - Of course parts of it apply. I wasn't talking about either the air resistance or terminal velocity. With a single compact piece, the energy to eject/throw that piece gets applied more efficiently to that single piece. With many smaller pieces, that force gets distributed among them. Are they going to all go in the desired direction straight ahead? Certainly not, which demonstrates the inefficiency. Very general concepts still apply even if not in space... – Broots Waymb Feb 26 '18 at 17:52
  • "[N]obody wants a death star covered in a thin layer of waste. Ew." Dude, it's a death star. It's not supposed to be nice. – David Richerby Feb 27 '18 at 14:02
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    @pepoluan I don't think that's technically canon, I believe ACPoV is treated as a bunch of stories told around the glowlamp – CBredlow Feb 27 '18 at 17:25
  • @CBredlow it's still marked as Canon, though. Not Legends. Lacking any other Canon material that contradicts it, ACPoV must be treated as Canon. Remember: There is no longer a "multilevel" Canon now; everything is either Canon or Legends. – pepoluan Apr 01 '18 at 08:57
  • @pepo It may be 100% canon that someone in the star wars universe told that story: framing matters. – Yakk Apr 01 '18 at 10:41
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The Death Star was 160km across. Trash from the centre has to be moved through at least 80 kilometres of station before it can be vented into space, so the more compact it is the better, if you don’t want your entire station to be taken up by garbage chutes. Vaporising it would use a lot of energy, and also change the problem to one of transporting a lot of very hot gas through those 80km, with the associated risks if a pipe bursts.

Mike Scott
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    I always assumed the "offices" of the DS were close to the surface and it was all mechanical systems and the "core" in the middle. Not sure any trash is regularly generated close to the center. – JPhi1618 Feb 22 '18 at 18:44
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    @JPhi1618 Well, there was that one guy that just threw an elderly man into a shaft. Litterbug. – zibadawa timmy Feb 22 '18 at 20:00
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    This answer could be improved by including the risks of venting hot gasses through insufficiently protected auxiliary exhaust ports. – Codes with Hammer Feb 22 '18 at 20:15
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    @zibadawatimmy Actually, the architects planned for the possibility of people being thrown into reactor shafts. The reactor would vaporize them, but as Mike Scott said, there's still a need to get rid of the hot gas whenever that happens (a surprisingly common occurrence in evil lairs such as this). Which is why they installed a small thermal exhaust port leading directly to the main reactor. – Ray Feb 22 '18 at 21:00
  • There's still going to be trash chutes all through the Death Star to get the trash to the compactor. Or if you want less chutes, you can add more compactors instead. It all amounts to roughly the same in the end. – Hand-E-Food Feb 22 '18 at 22:18
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    In hindsight, they probably should have vaporized the trash and vented the gas through that thermal exhaust port... you know, to use it for more than letting proton torpedoes into the core. – HopelessN00b Feb 22 '18 at 23:35
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    @HopelessN00b Since R2 was supposed to 'turn off all trash compactors on the prison floor', you can assume there were many compactors around. – Angew is no longer proud of SO Feb 23 '18 at 08:26
  • @Angew Detention. – Mark Feb 23 '18 at 13:51
  • @Mark Thanks for the correction. I saw the film many times in dubbed form and only a few times in English, so the quotations are stuck in my head in Czech (and I didn't verify before posting). – Angew is no longer proud of SO Feb 23 '18 at 14:23
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This is explained in the Official Star Wars Fact File #57. In short, the garbage system runs throughout the entire station, representing a festering pool of filth behind the pristine facade (get it?!)

All rubbish is placed into disposal chutes which are found in every room and quarter. These lead, via a series of tubes and chambers to large compactors and then into loading bays where they can be jettisoned into deep space, following standard Imperial procedures, when the Death Star goes into hyperspace.

Like the rest of the Imperial Navy, the Death Star boasted a clinical neatness. The battle station's pristine corridors and control rooms, with their gleaming white, grey and black surfaces, had an almost sterile aspect. Needless to say, this tidiness didn't just happen. Rather, it was achieved through a tough regime of waste disposal that was actively pursued by every single creature that lived and worked on the Death Star. Everything from building and maintenance materials, to food waste, to individuals' personal items, found its way into the Death Star's myriad trash compactors. Once it had arrived there, the waste was left to fester, for no thought was ever given to the recycling of these materials. Instead, it simply remained there until the Death Star next made the jump to light speed, at which point the waste was discharged into space, as per standard Imperial procedure.

The compaction is required in order to maximise the amount of garbage that can be stored, presumably in case the station remains stationary for an extended period.

RIVERS OF RUBBISH
Rubbish found its way into the trash compactors via an elaborate system of garbage chutes that ran throughout the length and breadth of the Death Star. All personal quarters had their own refuse disposal points that fed into the larger chutes like tributaries into a river.

Curiously, it was not uncommon to find girders and other construction materials lining the walls of the compactors, for these areas also tended to be used as skips. In order to maximize the amount of refuse that could be stored inside the compactors, their walls were designed to close together and crush the waste held inside.

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Valorum
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    At least someone put in the effort to finding an actual answer as opposed to silly anecdotes. – Edlothiad Feb 25 '18 at 11:09
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    This is Legends stuff, though. – pepoluan Feb 25 '18 at 13:26
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    @pepoluan - The Official Fact files were written as canon information. They've subsequently been "de-canonised" by Disney but I'm unaware of any source that actually contradicts this info. – Valorum Feb 25 '18 at 13:29
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    @Valorum you mean, de-canonised by Lucasfilm. I think I've told you a couple of months ago that Disney had no say in what's canon and what's not. And yes, there's currently no source that contradicts this info, but that does not change the fact that this info is Legends. – pepoluan Feb 25 '18 at 13:47
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    @pepoluan - The Lucasfilm Story group comprises those who originally worked for LucasFilm and those who've come over from Disney. They also set the "terms of reference" that the group operate under – Valorum Feb 25 '18 at 14:05
  • @Valorum please show me an official post stating that the LSG comprises Lucasfilm employees + "those who've come over from Disney". And please show me the "terms of reference" you're claiming to exist. – pepoluan Apr 01 '18 at 09:00
  • @pepoluan - Matt Martin, for example is a former exec at Disney Interactive. – Valorum Apr 01 '18 at 09:19
  • @pepoluan - The terms of reference were put together by Kathleen Kennedy after her promotion (post-acquisition by Disney) for the explicit reason that she and Disney felt that the EU had gone in "in too many different directions without any oversight by George and that's something we’re trying to rectify" - http://www.slashfilm.com/kathleen-kennedy-interview/2/ – Valorum Apr 01 '18 at 09:20
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The best reason is logistics. It would require much more energy to vaporize trash, then to just dump it overboard. While the Death Star has plenty of energy, the designers wouldn't want to waste it frying a piece of garbage. Especially considering the amount of garbage the station would generate.

The utility of the compaction would also be more economy of space. It would require a lot more volume of space to enable transportation of uncompacted garbage throughout the station. There would be conveyors everywhere, taking up much more space. If you transport it and dump it after it's compacted it's a much more efficient use of space.

theMaestro73
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  • Wouldn't you need conveyors everywhere to move the trash to the compactors? – JohnP Feb 22 '18 at 15:52
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    @JohnP at least in the one we saw, they use vertical chutes (which still take up space). Even if they did use conveyors, it's not about using NO space to transport garbage, it's about using as little space as possible, and using it most efficiently. It's more efficient to compact it closer to the point of generation, and transport it compacted. How close the compaction is to the point of generation was for the Imperial Engineers to decide. – theMaestro73 Feb 22 '18 at 15:57
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    Blast a whole planet? No problem. Blast a few tons of trash? That could be a problem. – Eric Duminil Feb 22 '18 at 18:50
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    "While the Death Star has plenty of energy, the designers wouldn't want to waste it frying a piece of garbage." You saw how Palpatine met his end, right? – ceejayoz Feb 22 '18 at 19:09
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    @ceejayoz protecting against accidentally frying the Emperor due to poor placement of the exhaust conduits wasn't in the spec and the drawings passed QA. Presumably it would have been corrected by a change order at great expense to the Empire when the safety hazard was identified by the commissioning team (though the Empire does seem to have a very dim view of occupational health and safety)... The Second Death star was incomplete at the battle of Endor, after all! – serakfalcon Feb 24 '18 at 10:03
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To compact trash

srsly though putting it in space is a bad idea for many reasons:

  1. space debris can be a serious problem, both to you and other ships in the fleet (even if you've got good materials to make things out of remember some of the trash will be made of those same materials ).

  2. prevents any reasonably priced recycling operations from taking place, if you compact it now however you can drop it off at Imperial trash co. for recycling purposes.

  3. it makes it difficult perform stealth operations if you are throwing shiny garbage out the side every so often (not important for the death star but you could argue imperial standard)

as for vaporising it.

  1. energy intensive, especially if you've got any fancy space trash with high melting points
  2. heat intensive (you've just made what amounts to an explosion INSIDE your death star and that energy needs to be gotten rid of)
  3. just overkill? like i mean just compact it dude

and both methods suffer from the problem that any toxic/explosive/radioactive hazards are ultimately not dealt with properly. imagine how you'd feel if your world had been heavily damaged not by the death-stars super laser but just because they dumped a bit too much uranium into your atmosphere .

Ummdustry
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Naval ships don't throw trash overboard randomly. That's how you get followed.

  1. If a large naval ship just threw trash overboard the moment they generated the trash, there'd be a continuous stream of trash being ejected. If an enemy had a day-old sighting of a battle group, a search pattern would quickly turn up trash - they could literally follow the trash. So in actuality, warships store their trash onboard and eject it at appropriate times. That's a protocol every sailor knows - throwing even a cigarette butt overboard will get you in trouble.

  2. Recall from The Last Jedi how it's generally assumed that jumps to lightspeed can't be tracked.

  3. Recall also from The Empire Strikes Back when Han Solo exploits the known fact that the Empire dumps their trash right before they jump to lightspeed.

All these things are connected. The Empire follows reasonable naval procedure. They dump right before a jump because finding trash there will not help an enemy locate them.

Since you're going to package your trash for planned release, compacting it makes sense.

Harper - Reinstate Monica
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  • It was a dramatic device to add a nicely suspenseful scene to the movie (though I did like the description of the pros and cons of throwing out loose vs compacted garbage) – user89108 Oct 04 '19 at 14:21
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You need to read one of my favorite articles from McSweeney's: "On the Implausibility of the Death Star's Trash Compactor" by Joshua Tyree.

I maintain that the trash compactor onboard the Death Star in Star Wars is implausible, unworkable, and moreover, inefficient.

The Trash Compactor Debate turns on whether the Death Star ejects its trash into space. I, for one, believe it does. Though we never see the Death Star ejecting its trash, we do see another Empire ship, the so-called Star Destroyer, ejecting its trash into space. I therefore see no reason to suspect that Empire protocol dictating that trash be ejected into space would not apply equally to all Empire spacecraft, including the Death Star.

...

user97057
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