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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

uhoh
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    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: https://space.stackexchange.com/questions/10432/would-the-life-support-systems-on-the-iss-and-sts-work-well-also-in-1g – Organic Marble May 15 '17 at 15:31
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    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. – Uwe May 15 '17 at 16:29
  • @Uwe that's really interesting! I never thought about that. Sure, when I cook glutenous rice it's really "cohesive", but hopefully it will work with "normal" rice, and beans and chick peas as well. Looking at all the ISS videos that have water and hands and towel experiments, the water just creeps over and envelopes anything that's not hydrophobic. When are they going to send up a transparent rice cooker for science? :) – uhoh May 15 '17 at 16:38
  • With no convection and the heating coils on one side of the pot, that's gonna get interesting. The water near the coils will get really hot, the rest, not so much. Steam explosions on one side, anyone? – Organic Marble May 15 '17 at 18:44
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    @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. – uhoh May 15 '17 at 18:52
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    Zojirushi makes the best rice cookers. Just throwing that out there. – Phiteros May 15 '17 at 19:03
  • @Phiteros and they have the cutest logo too: https://i.stack.imgur.com/qarwi.png – uhoh May 15 '17 at 19:07
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    @uhoh agreed. When it starts cooking, and when it finishes, it plays a little song. – Phiteros May 15 '17 at 19:07
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    Heat transfer will be a problem due to the absent convection. But you can heat the water before mixing it with the rice, after that the temperature should be kept only just below the boiling point. Heating may be done using microwaves instead of heating coils. – Uwe May 16 '17 at 08:49
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    To optimize the heat transfer put the rice and the water between two heated copper plates with temperature regulation to 90 to 95 °C. If the copper plates are about 1 cm thick and have a distance of 5 to 10 milimeters, steams explosions should not be possible. Plating the copper plates with tin would avoid contamination with poissonous copper. – Uwe May 20 '17 at 21:08
  • @Uwe that's really clever, I like that. I wonder, aren't most spacecraft atmospheres reduced pressure, like 0.5 bar? Would that affect the maximum temperature? – uhoh May 20 '17 at 21:44
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    Water boils at 100 °C and 1.013 bar, but at 82 °C and 0.51387 bar. Reducing the ambient pressure does reduce the boiling temperature. To avoid boiling at 0.5 bar, the temperature should be below 80 °C. – Uwe Jun 02 '17 at 19:42
  • @Uwe time to elaborate further on your thoughts! – uhoh Sep 19 '18 at 18:10
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    Spacecraft are generally at 1 atm these days, but pressure cookers don't care what the ambient pressure is and don't need to continuously release steam. Heating elements on one side aren't going to somehow cause a steam explosion on that side, interior pressure is going to be uniform, but they might cause burning. Giving the container an occasional swirl or toss would probably be better than a continuous centrifuge. – Christopher James Huff Sep 22 '18 at 23:52
  • @ChristopherJamesHuff Those are good points. Yes, if temperature can be safely and reliably regulated (certainly easier these days than it was with a kettle on a gas or wood stove) then there's no reason for that gravity-based pfft-pfft-pfft-pfft-pfft-pfft pressure regulator on top of traditional pressure cookers. – uhoh Sep 23 '18 at 04:45

3 Answers3

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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)

Saiboogu
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Sdarb
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  • 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. – uhoh Sep 20 '18 at 03:42
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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.

Nathan Tuggy
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Rajath Pai
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  • 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! – uhoh Sep 20 '18 at 03:37
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    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. – Rajath Pai Sep 20 '18 at 10:16
  • 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? – Avi Cherry Sep 21 '18 at 18:30
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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.

SF.
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