Preservation/condition of a dead body in space

[Junghalli]

OK, I have a question, about a story I'm thinking of writing. It concerns human explorers going to another star system in an STL ship and finding what they think is a derelict alien ship in orbit of the system's habitable planet. The derelict ship has been in medium-low orbit of the planet for the past 17,000 years. Exploring the ship they find an unopened dead cryotube that contains some alien who apparently didn't wake up at the end of the trip (it's a colony ship, the colony died out at some point). They open it up and are really confused to find the body of what is apparently a human female inside. There's more to it but that's the relevant part.

Now my question is, in what sort of state would the corpse be in? It's been trapped in what initially was a tube full of ice for 17,000 years. Initially I figured it would probably be a perfectly preserved ice mummy, but then I remembered that it's in orbit of a habitable (earthlike) planet, and the sunward facing side of craft in orbit of Earth as I remember can get quite warm. So, would you get more of what we think of when we hear "mummy" (a dessicated corpse) instead? And what would the effect be of having the thing sealed in a tub full of water that would be continually boiling and freezing as the temperature changed?

Maybe a lot would depend on where it was in the ship. If it was next to an outer wall it'd probably experience a lot of temperature changes, but what about if it was in the center of the ship? Would the central part of a well-insulated airless compartmentalized vessel around Earth orbit stay at a more-or-less consistent temperature? And would that temperature likely be above or below freezing point of water?

[Akhlut]

Is the derelict ship a total vacuum? If it is, the more important question is did the cryotube break and leak when the ship was in vacuum (as you said the tube was initially full of ice, indicating it is no longer filled with ice)? If so, then most of the ice probably sublimated off when it got warm enough, leaving a very dry, but probably recognizably human mummy, especially if the corpse is not exposed directly to any light or radiation. It might also be burnt all to hell, especially if it was exposed to the sun for really long periods and the interior of the ship got correspondingly hot.

If the tube broke and leaked before there was a vacuum, then the corpse would have been eaten by microbes only a few weeks or months after the tube broke, depending on how long it took for vacuum to set in and then for the corpse to dessicate.

[Junghalli]

Is the derelict ship a total vacuum?

Yes, or at any rate it's as close to a total vacuum as space itself. The original crew decompressed it when they abandoned it.

If it is, the more important question is did the cryotube break and leak when the ship was in vacuum (as you said the tube was initially full of ice, indicating it is no longer filled with ice)?

The tube is intact, there's just no power to the refrigeration unit. It's still full of the solution the body was kept in (probably originally water ice).

I think the cryotube is toward the center of a sealed chamber inside the ship. So it's not directly exposed to the sun, and doesn't directly touch anything exposed to the sun like an outer wall. The walls are well-insulated, so I imagine the temperature might have been fairly constant.

[Akhlut]

Hmm, the constant temperature changes and the fact that a few of the microorganisms on her body would have awoke from stasis would probably mean that the corpse would be devoured by microbes and there might just be a very thin slurry in the tube since all energy that could be metabolized probably has been in the tube. Basically, the only way to get a mummy would be for the tube to break after decompression so that the water sublimates off, leaving a dessicated mummy.

[Junghalli]

In that case I guess the easiest solution would be to have the shut-down procedures on the ship involve thawing and draining the cryotubes. It makes a certain amount of sense since having all that water constantly freezing and sublimating inside it would probably damage the tube over time. In that case I'd assume when they crack the tube they'd find a dessicated mummy.

One thing that occurs to me: the inside of the tube is small, wouldn't it still be a fairly wet environment just from the water in the person's body? Wouldn't that promote decay?

Hmm, come to think of it, maybe a better idea would be to have it be found in some sort of non-airtight body bag in a storage compartment or something. If I ever wanted to be able to use the ship again if I had to (which going through any sort of preparation in shutting it down would imply) I'd probably want to take the body out to prevent damage and contamination to the tube.

[Akhlut]

I'd think the vacuum of space would lower the vapor point of water so much that the body would dessicate quickly enough for it not to rot (or, at least, no more than some naturally occurring mummies in mountains), especially if the solution the body was stored in was salty or something like that.

[Sikon]

Maybe a lot would depend on where it was in the ship.

If you want to have it keep frozen all the time, to be well-preserved like dead mammoths found in glaciers on earth, you could suppose it was in a well-shaded area of the ship. Details depend on the amount of infrared radiation intercepting it emitted from warmer portions of the ship, conductivity through ship structure, as well as the assumption it is lucky enough for surrounding geometry to keep it in constant shade. But ideally it might end up in a situation like the ancient ice from old cometary impacts theorized to survive in permanently-shadowed crater bottoms in polar regions on the Moon.

With no atmosphere scattering light, such ice in those shadowed lunar polar craters is in near-total darkness. No surrounding atmosphere causes convective heat transfer, and the thermal conductivity of the surrounding dirt in between them and sunlit areas is rather low, causing such to stay at temperatures like even 40 K or thus 230 degrees Celsius below zero. Meanwhile, then, for example, "for temperatures below 70 K, the sublimation rate of an exposed ice surface is much less than one molecule of water vapor lost per square centimeter of surface per hour." When sublimation is orders of magnitude less than it is at higher temperatures, such a block of ice can last intact halfway forever.

Of course, the ice around the corpse could easily alternatively end up warm enough to sublimate much faster or even melted and rapidly evaporating if it wasn't in such a fortunate location, but it might survive if so shadowed. Perhaps the cryotube module was designed to be kept shaded and insulated from sunlit regions of the ship, since, even if the builders never intended 17000 years, maybe they still meant for it to last a while with little to no active cooling system needed.