This is not nice perspective, but eventually it will happen. An astronaut falls out of spaceship because of damage caused by collision with other object, or because of suit decompression. The fluids from the body would evaporate, and if any bacteria would survive, than only as spores.

Does it mean the perfect mummification of the body? Or there will be some decay, caused by enzymes from damaged cells, for example?

  • 6
    $\begingroup$ I would be very surprised if such experiments (with animals, not humans of course) have not been conducted by both US and Russian space programs. So it would be nice if the answer could cite some papers. $\endgroup$
    – user54
    Jul 17, 2013 at 21:02
  • $\begingroup$ @horsh all assumptions aside, the answers thus far have not cited real data as to what has happened experimentally to carcasses exposed to a space environment. $\endgroup$ Apr 4, 2014 at 19:15
  • $\begingroup$ I don't think a body in space woudl freeze, because of the vacuum heat might not be exchanged and thus it would remain in the corpse $\endgroup$
    – Ans
    Apr 20, 2016 at 11:32
  • $\begingroup$ I always thought that if the depressurization is fast enough, for instance from a break in a space suit, then the internal pressure of the body would make it explode. Is this conceivable? So, what you have been describing here would only apply if the body is exposed to vacuum starting some time after death. $\endgroup$
    – Alberto
    Jan 28, 2017 at 19:20

4 Answers 4


It would seem that the ultra-cold vacuum would kill off most of the bacteria, etc in the body, as well as quickly boil off all of the water content. Here's a lovely description of the process from Focus magazine:

In space we can assume that there would be no external organisms such as insects and fungi to break down the body, but we still carry plenty of bacteria with us. Left unchecked, these would rapidly multiply and cause putrefaction of a corpse on board the shuttle or the ISS. Drifting exposed in the vacuum of space itself, however, this process would rapidly slow to a halt.

The low pressure would initially boil off most of the water and what was left would freeze, halting any biological processes. Depending on the trajectory of the corpse, there might be some warming from the side facing the Sun, but all this would do is accelerate the rate of water loss, leaving only a dried husk.

  • 3
    $\begingroup$ Charming text. Still, it is not totally clear what would happen. It is also disputed, how e.g. bacteria would handle the situation. For an example, see Streptococcus mitis on the Moon. $\endgroup$
    – s-m-e
    Jul 18, 2013 at 14:35
  • 1
    $\begingroup$ @ernestopheles it is clear: without water, life won't (can't) do anything. Most life will die promptly, and while some types will persist in suspension, they absolutely must hold on to what little bit of water that hydrates various biomolecules (proteins, nucleic acids) or else they will be destroyed. Given enough time in deep space, all water will ultimately leave them (though if they're stuck to a comet that could buy them eons), and being anywhere near the sun will drastically accelerate that. $\endgroup$
    – Nick T
    Feb 20, 2015 at 3:33

Other than decay caused on Earth by microorganisms, other factors for decay in space, where decay is defined as loss of pristine mummification of the original, freeze-dried corpse:

  1. A body in orbit around the Sun would be impacted by the solar radiation. A quick search only found research on live tissue. Presumably, this would cause some disintegration of the mummified cells as well. It is unclear if orbital decay or solar wind damage would be the more significant erosion/decay vehicle.

  2. A body in orbit around a planet would likely lose all cohesiveness to orbital decay prior to any significant loss due to other means.

  3. A body drifting in open space, would be subject to micro meteor strikes as well as attraction to any other drifting bodies.

There are many factors; while the mummified body would not decay as fast as an Earth-bound body, it would not be eternally preserved.

  • $\begingroup$ Great answer: I'd also add that the freeze/thaw cycle (if the body orbited in and out of the sun) would also cause some 'erosion' - or breakdown of tissues and structures. $\endgroup$
    – john3103
    Oct 17, 2013 at 17:28

Adding to the other answers, the body may decay very fast when colliding with space debris - depending on it's size. Probably more like 'exploding', as it would be brittle after freezing.

This assumes that the body is in an orbit where other debris exists - put that seems probable to me in general.

  • $\begingroup$ A body won't be necessarilly frozen. On the orbit around Earth the Sun radiation (on the day side) is strong enough to heat a body to significant temperature. $\endgroup$
    – mpv
    Apr 4, 2014 at 9:18
  • $\begingroup$ Ok. But thinking about the typical speed difference when space debris collides ("A lot. Really."), it may not matter that much except for the count of resulting particles. And, as others describe, it would also dry out by boiling, and later sublimation of the water, ending up at least somewhat brittle without being frozen. $\endgroup$ Apr 4, 2014 at 9:27

Answer: It depends.

You need to specify the situation.

Dr. Frank Poole found himself in a depressurize spacesuit, in a frigid orbit around Jupiter back in 2001. He likely froze solid before gut microbes had a chance to recycle him.

In 2013, Sandra Bullock found herself in Low Earth Orbit in a sealed suit, anticipating a warmer, but slower, death by asphyxia. Slowly rotating like a supermarket rotisserie chicken, her microbes would have plenty of time to keep her suit pressurized with tissue break-down gasses.

The end state of these two corpsicles would be quite different.

Even completely sterile tissue breaks down after death. Without oxygen-driven metabolism, compartmentalization inside the cells breaks down. Digestive enzymes are released and the cell auto-digests. This process is markedly slowed at low temperature, and essentially stops once frozen.

Similarly with micro organisms: their chemical machinery stops once frozen.

So the essential question is the rate of cooling. Sandra, who will be exposed to direct sunlight half her orbit and to the IR radiation of night-side Earth the rest of the time, will equilibrate to a temperature which may well be above freezing. Frank will largely be exposed to the background microwave temperature and get little warmth from the distant Sun.

  • 1
    $\begingroup$ for those who aren't media savvy: Woody's referring to the movies 2001: A Space Odyssey and Gravity. I don't remember the name of Sandra Bullock's character either. $\endgroup$
    – Erin Anne
    Nov 9, 2023 at 2:42
  • $\begingroup$ George Clooney floated away to his demise in Gravity, similar to Frank Poole in 2001, although Clooney's spacesuit was still pressurized. Also being in low Earth orbit the Sun's heat would have presumably kept the biological processes going longer, although being in LEO his body would not have remained in orbit nearly as long as Poole's. $\endgroup$ Nov 9, 2023 at 11:30