Providing a theoretical journey to some far place, could the void of space be used as a good refrigerator for food since it is very cold ?

Assuming that radiations in the void space are somehow avoided for such idea, is this viable ?

Also, what about the vacuum of space, would food be affected by such condition and require a human-friendly pressure level ?

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    $\begingroup$ Vacuum-packaged food should be fine ;-) $\endgroup$ – gerrit Jun 25 '14 at 20:53

On planet earth, food spoils for several reasons:

  • Oxidation
  • Dehydration
  • Microorganisms

Oxidation is a reaction with the oxygen in the atmosphere. You can witness this when you cut an apple in half and leave it. It will only take minutes until the cuts become brown. Oxidation is usually harmless, but often gives the food an unpleasant texture, look and/or taste. In the vacuum of space there is no oxygen, so by storing food in space, oxidation can be prevented.

Dehydration is when food loses moisture to the atmosphere. It becomes dry and stale. This often does not affect the nutritious value, but gives most kinds of food an unpleasant texture. Food dehydrates because its own moisture is higher than the moisture of the atmosphere. The moisture of space is 0, so being exposed to vacuum greatly increases the dehydration process. However, some kinds of food can be rehydrated by adding water.

Of all the kinds of spoiling mentioned here, microorganism growth is by far the most harmful one. It is practically impossible to produce food in a completely sterile way. Any food product will have smaller or larger traces of bacteria or fungi ("mold") on it or will get contaminated with these during transport and storage. In small quantities, the human body can deal with ingesting them. In fact, most of these organisms themself aren't even toxic. But when the environment the food is stored in is beneficial, these organisms will procreate. They will consume parts of the food and turn it into chemicals which are often toxic to humans (see "Mycotoxins"). However, almost all of such microorganisms require a pressurized atmosphere. In vacuum, they either die or become dormant. That means storing food in vacuum is a great way to preserve food from mold and bacteria.

tl;dr: Food in vacuum of space will dry up immediately, but when you don't care about that, it will be preserved really well.

  • $\begingroup$ Thank you Philipp. Your explanation is much clearer than mine! $\endgroup$ – dotancohen Jun 27 '14 at 14:33
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    $\begingroup$ Canned food (regular cans at the supermarket) might degrade in quality over long time, but I think in general it doesn't experience much biological activity. You don't think it's sterile? What about things sealed in plastic and heated to similar temperatures as the cans, or picowaved. You don't think those are sterile? I have a plastic bag of kimchi that's been sitting on my table for six months - I'm sure it's "dead" or it would have exploded by now! You don't think that's sterile? $\endgroup$ – uhoh Aug 11 '16 at 14:42
  • $\begingroup$ @uhoh Even assuming that every single microorganism in those plastic containers was killed by some process, the plastic itself might be porous or become porous over time through damage or deterioration, so the content becomes contaminated later. Remember that a single surviving bacterium is enough to start a whole population. There are some extremophile microorganisms which can take quite a lot of punishment. $\endgroup$ – Philipp Aug 11 '16 at 15:07
  • $\begingroup$ OK I understand what you mean. I don't 100% agree - extremophiles are stretching it. So far as we know they stay put in their extreme environments and don't contaminate food processing facilities. yet! (That's what keeps me up at night). Plastic bags just aren't porous, and unless damage, good quality food-grade plastic will be around quite a while. Much longer than the food inside will need to naturally chemically loose quality (at least some items). But these are really my opinions - I am not a food safety expert. $\endgroup$ – uhoh Aug 11 '16 at 15:22
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    $\begingroup$ I just happened to have read/listened to this - it's about kimchee brought to the ISS with South Korea's first Astronaut Soyeon Yi. She explains that one dish was canned, the other freeze dried, but they were also irradiated for complete sterilization before it could be transported safely to the ISS. I'd mentioned kimchee above already so I thought it seemed at least a bit relevant. (fermenting foods can produce gas and burst their packaging.) $\endgroup$ – uhoh Aug 22 '16 at 13:54

The effect of the void of space is not so much cold, rather it is an insulator. Though heat radiates away, there is no convection nor conduction. Many spacecraft take precautions not to overheat in space, very few spacecraft have a too-cold condition. Even the Spitzer space telescope has since warmed up since the coolant ran out.

Additionally, the void of space will likely remove most of the moisture from the food. Though much food is "dried", even dried food contains a significant portion of water. The void of space will destroy this, and other potential volatiles in the food as well.

  • $\begingroup$ +1 : your answer is complementary to the one above, thanks. $\endgroup$ – Aybe Jun 28 '14 at 13:43

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