Because of where I'm currently living, I've gotten used to using a small rice cooker regularly.

@Tristan has pointed out that cooking dried rice, or dried beans in boiling water could not be done in the same way on board a spacecraft.

I have a hunch someone has already invented a zero gravity rice cooker, perhaps published, perhaps not.

Can someone speculate how one might work on board a spacecraft? You add dried rice or beans, then add water, then close it. On Earth, the water and ingredients stay in the bottom, and the steam goes out the top, gently lifting the loose-fitting lid. Without gravity, how could one keep the boiling water and the ingredients together, and yet have steam come out safely?

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above: Rice cooker (surprisingly, exactly what I have). From here

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above: Diagram of a rice cooker. This is the older, purely electromechanical kind. After cooking is done, the main heater turns off (related to the magnet?) but the warmer stays on. From here.

A potential user: https://twitter.com/yousuck2020/status/1042209952217985024

wide demo pic

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    $\begingroup$ Meter-diameter centrifuge? Apart from the size, this is basically how the distillery in the ISS waste water processor works. See my answer to this question: space.stackexchange.com/questions/10432/… $\endgroup$ – Organic Marble May 15 '17 at 15:31
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    $\begingroup$ Adhesion would keep water and rice together. Boiling water is not necessary to cook rice, keeping the temperature just below boiling point should do. Just use some less water to compensate for less steam. Cooking rice sticky but not grainy would be better for eating in zero gravity. $\endgroup$ – Uwe May 15 '17 at 16:29
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    $\begingroup$ @OrganicMarble I think Uwe's comments are insightful. It wouldn't be built like an Earth cooker at all, and it may not really need to boil off a lot of steam. Without gravity, the water would tend to coat all of the ingredients under it's own forces. Maybe a simple plunger would be enough to push it all to the heated section, if there weren't any centrifugal artificial "cooking" gravity. $\endgroup$ – uhoh May 15 '17 at 18:52
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    $\begingroup$ Zojirushi makes the best rice cookers. Just throwing that out there. $\endgroup$ – Phiteros May 15 '17 at 19:03
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    $\begingroup$ @uhoh agreed. When it starts cooking, and when it finishes, it plays a little song. $\endgroup$ – Phiteros May 15 '17 at 19:07

Space is a very sensitive environment and the mission control usually likes to be in control of everything and hence it's heavily monitored. Small particulates that can escape and clog filters, hot fluids that can't be recycled and/or accurately modeled in a flow within space stations or in space are generally not preferred. You can actually see with many videos by astronauts that they just like to leave their food hanging while they get something else. Here's one by ESA about rice. It looks like it is cooked rice and possible needed rehydration and reheating. The Japanese have ready-made sticky rice available and it doesn't go bad for up to a year. Something similar may be employed to provide astronauts with such fresh ingredients and not a paste full of nutrition and no taste.

is the video if you like it.

If you were looking to theorize on cooking rice grains in space, might I suggest a setup where one could cook rice for a long duration in hot water but not bring it to a boil? Soaking rice makes it easy to cook as it hydrates and becomes quite tender and easy to cook. Cooking at low temperatures may seem a bit of a long time stretch but well, they may have all the time in the world to wait for it.

  • $\begingroup$ Your answer is really interesting! I've never prepared rice manually so I didn't know there was such flexibility (see How to prepare rice in a very real emergency - no boiling (no electricity or alternatives)?) Probably a 20 kg bag of dry rice would be a particularly bad idea for spaceflight, so the roughy 20% extra weight for individual pre-packaging may be unavoidable. Thanks for the video as well! $\endgroup$ – uhoh Sep 20 '18 at 3:37
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    $\begingroup$ 20 kg of a particular raw food might be incredibly stupid on a space mission. Space missions usually involve non trivial things there and aren't bothered by the gourmet level cooking. Space food has always inspired many different things on earth as well. I saw a vending machine filled with nutrition pastes in the moscow airport. This question was quite interesting as well as something up my sleeve.You probably got better answers in the seasoned advice stack exchange. $\endgroup$ – Rajath Pai Sep 20 '18 at 10:16
  • $\begingroup$ On the other hand, since we're talking about BFR mission in particular here, remember that the capsule is VERY large and there will only be 8-12 people in an area designed to seat 100. I think the idea of them bringing along a gourmet chef to prepare fresh meals is not entirely out of the question. Maybe one of the artists who makes it on board will end up being a chef? $\endgroup$ – Avi Cherry Sep 21 '18 at 18:30

Most foods cooked in space are not brought up to a complete boil because dealing with the steam would be an issue. Currently they inject hot water into vaccuum sealed pouches containing food. I would expect that instead of a zero G rice cooker, spaceX would send par-cooked rice or instant rice that only requires hot water to be added. Instant rice is pre-cooked and dried out so it just needs water added to rehydrate and can be rehydrated with cold water (but that wouldn't be very appetizing)

  • $\begingroup$ Thanks! Here and here I've brought up the idea of bags of dried beans and rice as bulk foodstuff for maximizing nutrition/weight ratio, but perhaps that's not such a good idea, and the individual, prepackaged meals are required for reasons beyond just convenience. $\endgroup$ – uhoh Sep 20 '18 at 3:42

Fold the top of the pot towards the middle, making the lid much smaller. Make it spin inside the case as it's heated. It doesn't have to spin very fast; you don't need full 1g, just a small amount of g-force to enable convection. The steam vent should be in the center, able to pivot and connected to water reclamation system. And the whole cooker should be attachable to the surface, even with some velcro, or it will counter-spin around the pot.

Rice would probably need to be put in the pot in perforated bags, the kind like parboiled rice is sold in - filling the cooker with loose dry grain would be tricky. Once cooked it should be sticky enough not to cause problems.

  • $\begingroup$ I wish I could up vote twice here. I still like this answer. $\endgroup$ – uhoh Oct 25 '18 at 12:51

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