Food Consumption in Orbit

[Sonnenburg]

I was thinking about long-term labs/bases in orbit and such and was wondering how much a person would need to consume annually in order to function. Anyone have any ideas on the numbers for someone on an orbiting station? The moon? Mars? If anyone has any info I'd like to hear it.

[wilfulton]

While I don't know exactly, I believe astronauts in space consume about 4000 calories a day (remember they have to exercise a lot to maintain muscle and bone density, the human body is not intended for long periods in weightlessness).

I couldn't tell you about water, but if you're burning 4000 calories a day, you're probably going to sweat like a pig, and that water does have to be replaced.

[Wyrm]

I couldn't tell you about water, but if you're burning 4000 calories a day, you're probably going to sweat like a pig, and that water does have to be replaced.

Water, however, can be reclaimed. Indeed, if you're "sweating like a pig", you MUST reclaim that water from the air, or condensation will kill your spacecraft's electronics.

Distilation is very effective in making water potable, and any slack that the distilation process doesn't cover, activated charcoal filters can usually cover. The good thing is that if you have dehumidifiers, then you get the vaporization step for free (in the case of the water that evaporates in the afforementioned sweating like a pig).

The Texas rule is seven gallons a day for normal temperatures and heavy exercise, which you will have in a climate-controlled spacecraft (no Death Valey rules here). You need that much water for each day water remains in the reclaimation cycle. This is, of course, ignoring losses due to imperfections in the reclamation cycle.

[John of the Dead]

The Texas rule is seven gallons a day for normal temperatures and heavy exercise, which you will have in a climate-controlled spacecraft (no Death Valey rules here). You need that much water for each day water remains in the reclaimation cycle. This is, of course, ignoring losses due to imperfections in the reclamation cycle.

Can you explain "The Texas rule," please? Seven gallons seems like an awful lot, unless you're counting cooking and sanitation. Seven quarts seems far more reasonable, unless there's something I'm missing.

[wilfulton]

Seven gallons is an awful lot. Even during heavy physical activity/high temperatures, a person only needs about one quart or so per hour. Drinking seven gallons would not only result in non stop piss breaks, but could also lead to overhydration, which happens when you drink so much that you flush the electrolytes out of your body, and that's no good either.

Hmpf, I guess I did momentarily forget about the idea of reclaiming water. Even so, it's generally a good idea to have some backups on hand in case Murphy decides to fuck with your reclaimer just prior to launch.

[Wyrm]

The Texas rule is seven gallons a day for normal temperatures and heavy exercise, which you will have in a climate-controlled spacecraft (no Death Valey rules here). You need that much water for each day water remains in the reclaimation cycle. This is, of course, ignoring losses due to imperfections in the reclamation cycle.

Can you explain "The Texas rule," please? Seven gallons seems like an awful lot, unless you're counting cooking and sanitation. Seven quarts seems far more reasonable, unless there's something I'm missing.

Erm, yeah. It was quarts, not gallons. Damn you Imperial measurement!

[Winston Blake]

I was thinking about long-term labs/bases in orbit and such and was wondering how much a person would need to consume annually in order to function. Anyone have any ideas on the numbers for someone on an orbiting station? The moon? Mars? If anyone has any info I'd like to hear it.

The bare-minimum of consumables mass looks like 0.98 kg water, 2.3 kg food, and 0.0576 kg air per person per day. About 3.3 kg total, round it up to 4. People actually need 2.72 kg of water, but since food is 75% water, it contains an additional 1.72 kgs.