# How long does it take for biological matter to decay in space?

I have been looking up a few different theories lately. And one of those is the idea that intelligent life cannot exist for any long period of time without eradicating itself or being destroyed by outside influences.

My question assumes all hypothetical life that may exist within 30LY of Earth died between now and 200yrs from now. With humanity managing to obtain a limited form of faster than light travel by 250 years from now. Would the bodies of these life forms still be intact inside of their spaceships in the cold depths of the void?

Let me know if this is likely. I suspect they'd mummify but I am not 100% sure.

• It would completely depend on how they died and the conditions the bodies are left in. Microbes do exist in space as they are carried in on our bodies, so the dead could decay. Jan 22, 2019 at 6:26
• what-if.xkcd.com/134 - on the issue of dead bodies in space. With comics.
– Erik
Jan 22, 2019 at 9:08
• Oh xkcd, what would we do without you? Not have freeze dried astronaut ice cream probably. But where is the fun in that? Thanks for the link Erik. Jan 23, 2019 at 10:19

It depends on the size of the biological matter.

In space you have mainly two factors of hostility:

1. extreme temperatures

Extreme temperatures are dangerous for preservation only on the hot extreme, since they break down organic molecules into smaller components. When they are on the cold extreme they are advantageous. Deep space frozen matter doesn't change that much, so the same holds for organic matter. If the freezing is slow, you might get collateral damages by the formation of ice crystals. Here size matters: the bigger the sample, the longer it will take to freeze, as the only way to lose heat in the vacuum of space is by radiating it. And the longer it takes to freeze, the bigger ice crystals can form.

Radiation and energetic particles instead bring damage whenever they interact with matter, including organic matter. Since the damage is dose dependent, and the absorbed dose increases with the volume of matter, it follows that the bigger the sample the bigger the damage. So, a human body might get more damage than a bacterial spore. Moreover, a human body is a tad more complex than a bacteria in its working, therefore it's also more sensitive to damages, simply because there are more mechanisms that can get broken.

Would the bodies of these life forms still be intact inside of their spaceships in the cold depths of the void?

Completely intact no, they would be frozen and dehydrated, resembling an Oetzi. However, they would not be rotting away, in reason of their frozen status. caution should be exerted on handling them, as they would be extremely fragile.

• Extreme cold temperatures damage the structure of cells and capillaries. Jan 22, 2019 at 7:12
• @JoeBloggs, added a clarification on that
– L.Dutch
Jan 22, 2019 at 7:21
• Don't forget that cycles of freezing and thawing would multiply the damage by some factor, at least until the bodies are dehydrated. Jan 22, 2019 at 10:44
• Radiation damage is dose dependent, but it depends on dose per weight unit, not on total dose. That is, the number of broken molecules may be proportional to total dose, but what matters is the proportion of broken molecules. Therefore, larger samples aren't getting more radiation damage. In fact, large samples can even afford some better radiation protection to its interior, although this could be debatable.
– Pere
Jan 24, 2019 at 10:02
• Think of freezer burn carried to its logical conclusion. Jan 25, 2019 at 23:37

Yes. Since we're talking inside a ship, I think there'd be a very good chance the bodies would still be there. If the atmosphere has been vented, that is. You'd have some very well preserved mummies. The ship itself (depending on the technology) would protect the bodies from the worst of the radiation and from minor impacts. And may even offer some level of protection from heat extremes (though as you seem to be implying deep space, heat probably won't be an issue). This is of course assuming human-like physiology.

If the atmosphere is still in place, or for that matter, if the life support system is still working, you'd get basically whatever decomposition would be natural in those conditions for that species. Keep in mind decomposition may alter the atmosphere in the ship, using up O2 and producing CO2. So at some point, if there's not enough of it, it may stall.