Currently, doing laundry in microgravity is an unsolved engineering problem. The result is that clean clothes on the International Space Station have become a consumable resource. Clean clothes get launched to the space station regularly. When they are too dirty to wear, they just get stuffed into a used cargo capsule as trash.

For a more long-term mission where supply flights are not an option, like a manned Mars mission for example, this would be a problem. Shipping enough clothes for 9 months (even more when you don't want to wash clothes while staying on the Mars surface) would require quite a lot of valuable payload capacity.

But what about the simplest solution: Just don't wear any clothes. Human body hygiene in space is a solved problem. When astronauts stay nude during most of their intra-vehicular activities, the need for fresh clothes could be drastically reduced.

  • The astronauts are in a controlled environment, so protection from the weather is not required.
  • The everyday clothes ISS astronauts are wearing aren't going to protect them against any of the dangers of space travel, so safety is not an argument either.
  • The cultural stigma against nudity between the astronauts can be overcome. Nudist movements all around the world show that it is perfectly possible to have normal social interactions without wearing clothes.
  • The modesty of the astronauts towards the general public can be preserved by not livestreaming the whole mission. The long transfer phases between Earth and Mars are boring anyway. Public interest in actually seeing the astronauts can be limited to the critical mission phases. But these would just be a tiny fraction of the overall mission time. The astronauts could get dressed just for these occasions.

Am I overlooking some problems which would arise if astronauts would not wear clothes at all times and which would outweigh the problems caused by managing laundry?

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – PearsonArtPhoto Jan 2 '18 at 13:08
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    $\begingroup$ "The everyday clothes ISS astronauts are wearing aren't going to protect them against any of the dangers of space travel, so safety is not an argument either." - hmm, this one is just wrong. It would be like asserting you could wear no clothes in a lab or light factory or kitchen. $\endgroup$ – Fattie Jan 2 '18 at 15:44
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    $\begingroup$ hi @Ooker ! Notice the images below. The inside of a spacecraft is more slightly dangerous than a lab, light factory, or kitchen. (Indeed, it is all those things.) $\endgroup$ – Fattie Jan 2 '18 at 16:07
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    $\begingroup$ Hi @ooker, it's pretty nonsensical. You wouldn't go with no clothes in a kitchen or a lab. Right? (if you don't agree with that, I'm not sure what to say.) Minor injuries on a spacecraft are strongly to be avoided. Just look at the two pictures below. (Really, I'd probably also wear light gloves in there - exactly as mechanics or house-builders often do.) $\endgroup$ – Fattie Jan 2 '18 at 16:52
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    $\begingroup$ Another issue is you of course don't want feces, urine, menstrual fluid, sweat etc accumulating on surfaces. Indeed, this is of course exactly why nudists (which is great, viva FKK) often have a little towel or whatever for when they sit on chairs, use a bicycle, etc. It's a fun suggestion but a bit impractical. $\endgroup$ – Fattie Jan 2 '18 at 16:54

Clothes require laundry because they have accumulated dirt and other materials from the environment and their wearer. If the astronaut was not wearing those clothes then that material they captured would be released to the environment. In the space station it is a closed environment where such dirt and material would contribute to the accumulated hazards.

The purpose of clothes it to capture that material, such as dead skin, bodily fluids (such as sweat and so forth) and enable it to be disposed of. On earth we dispose of that material by recycling the clothes in a process we call laundry. In space it is more efficient to dispose of the hazardous material (we call dirt) within the capture container (we call clothes).

The other purpose of the clothes is to protect the astronauts from other day-to-day hazards to their body, such as abrasions and impacts. Socks, in particular, are quite important on the ISS as they protect the feet from the abrasions when hooked around the holding-bars when they are using their hand for work. Without this they would either be unable to work or would have sore upper feet.

Your implication that clothes are for modesty only only shows your gravity based cultural mind-set. In micro-gravity things look somewhat different.

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    $\begingroup$ @isanae I tried to locate the referenced source according to PubMed: ncbi.nlm.nih.gov/pubmed?term=Beamer%2C%20Paloma%5BAuthor%5D - and it appears to be this article ncbi.nlm.nih.gov/pubmed/19924944. An initial skimming of the text indicates that this is about modelling the source of the metals As and Pb indoors, and not as much about how much of dust is human skin. $\endgroup$ – Thorbjørn Ravn Andersen Jan 1 '18 at 8:07
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    $\begingroup$ only only shows your gravity based cultural mind-set ... ok that made me laugh... +1. $\endgroup$ – David Grinberg Jan 1 '18 at 18:21
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    $\begingroup$ I might have missed the point, but why capturing dust and human skin is important? What hazards can it be? $\endgroup$ – Ooker Jan 2 '18 at 3:47
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    $\begingroup$ For the “capture dead skin and sweat” argument to be valid you’d have to cover much more skin, especially the head. $\endgroup$ – Michael Jan 2 '18 at 8:52
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    $\begingroup$ @Luaan "You can't exactly open the window or use a vacuum cleaner" - I beg to differ. The window is one hell of a vacuum cleaner (and fire extinguisher, too). Just be sure to suit up and tie down everything that isn't dirt before you open it... $\endgroup$ – aroth Jan 2 '18 at 16:01

Clothing performs essential duties on the station in addition to modesty. They are an easy way to organize stuff. In addition to pockets, clothing is festooned with velcro strips for attaching tools, pens etc.

astronaut clothing

NASA is working on methods for washing clothes in space. Not surprisingly, they've studied the tradeoffs between including a washing machine in the mission and just supplying enough clean clothes to last the mission. The breakeven point for a washing machine is missions of about 1 year. For the ISS, missions are shorter than that and there are frequent resupplies, so it wasn't necessary to develop a washing machine earlier. For a Mars mission, it may become necessary.

The same argument for not wearing clothes in space is true for life on Earth: it'd be cheaper to run around naked. Less frequent washing and reduced wear would save money. Yet, nobody's doing that here on Earth.

Nudists are a small subset of humans, suggesting modesty is not that easy to dispense with. I think we can file this idea under N for 'non-starter'.

Additional possible rationales for not having a washing machine on the ISS: Adding a washing machine would place additional loads on the station's systems (water recycling, electricity), plus it'd be another non-science item to develop, operate and maintain.

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    $\begingroup$ Most climate zones of the Earth are either too hot and sunny or to cold for nudism during the whole year. But there are some first nations of New Guinea and Australia who lived some decades ago wearing very few clothing. $\endgroup$ – Uwe Dec 31 '17 at 20:06
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    $\begingroup$ Not to mention protecting against bugs, softening the feeling of sharp objects (thorns, branches, etc.), and serving an aesthetic function. $\endgroup$ – Tin Man Jan 1 '18 at 13:36
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    $\begingroup$ Uhh, I'm naked when I'm home alone for a long period $\endgroup$ – Ooker Jan 2 '18 at 3:44
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    $\begingroup$ "The breakeven point for a washing machine is missions of about 1 year." Couldn't it be said that the ISS' "mission" is 19 years (and counting)? It's not like the laundry machine will be consumed by the crew during their mission. $\endgroup$ – Alexander Jan 2 '18 at 8:10
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    $\begingroup$ "Nudists are a small subset of humans..." Within socially-constrained Western-European norms, yes - but that is only because of social norms. For the San or Aboriginal Australians, for a couple of examples, a different environment gives rise to a completely different set of social norms. Bare breasts are the most obvious example, where it is utterly unacceptable in normal Western life and barely (!) acceptable in liminal zones such as beaches, but most tribes in tropical/subtropical areas would never wear tops. $\endgroup$ – Graham Jan 3 '18 at 13:43

In addition to capture of contaminants, such as dead skin, hair, sweat, etc, and abrasion/cut protection, clothing forms a basic thermal layer that allows the human body to better regulate its internal temperature and perceived comfort level.

Every human has variations in temperature, and even in a perfectly controlled environment once you place two humans inside it you'll find it's only perfect for one or the other, and that this can change over time based on activity. They can adapt in a variety of ways, but the simplest is to wear clothing which conveniently serves several purposes in addition to easier thermal regulation.

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    $\begingroup$ A human body has its own temperature regulation. Adaptation to an environment temperature some degrees colder or hoter is possible. Clothing expands the acceptable temperature range. $\endgroup$ – Uwe Jan 1 '18 at 16:45
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    $\begingroup$ @Uwe Correct, however clothing doesn't just extend the acceptable temperature range, it also reduces unnecessary energy expenditure in temperature ranges suitable for nudity. For instance when sleeping they would still choose to use a sleeping bag with insulation not just to avoid floating around but to reduce the amount of energy the body needs to maintain regulation. The same is true during the active part of their workday. $\endgroup$ – Adam Davis Jan 1 '18 at 18:41
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    $\begingroup$ Saving body energy by clothing is important in space. If energy for temperature regulation is reduced, the astronaut would need less food and less precious payload weight is used by food. $\endgroup$ – Uwe Jan 1 '18 at 19:34
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    $\begingroup$ @Uwe Spacecraft have trouble keeping cold, not hot. Even just the life support systems produce enough waste heat to keep the temperature far higher than comfortable (and the colder it is, the harder it is to keep cold - the ISS radiators need to be so big exactly because the temperature they need to maintain is so low). The temperature inside the ISS is kept to the comfort of the crew even now - it would be cheaper to have it higher. Add direct sunlight (very relevant on an interplanetary voyage) and you can get the air as hot as you want even with all the systems down. $\endgroup$ – Luaan Jan 2 '18 at 14:52
  • $\begingroup$ Different people have different comfortable ranges (as indicated by the photo in Hobbes's answer: one in a fleece, the other in shorts). Assuming you want to avoid sweating (contamination, loss of grip etc.) and shivering (waste of energy), clothing allows the same environment to suit more people. On top of this, the heat generated by a person varies with effort even on a shared task (e.g. one person reads instructions to another who's tightening bolts) $\endgroup$ – Chris H Jan 4 '18 at 14:44

A picture might be worth a thousand words. Just imagine this situation without clothes:

Upside Down

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    $\begingroup$ I don't understand your visual argument. Perhaps you'd like to explain further with words. $\endgroup$ – R.M. Jan 2 '18 at 17:34
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    $\begingroup$ @R.M. I'm looking at this example as tight spaces can be unpleasant without clothing... Guy in Black's groin area is inches from the woman's head/face. (looks like she is actually colliding with him shoulder to hip.) Regardless of your modesty level or how you feel about your co-workers, I don't imagine it would be fun to work with someone else's junk in your face. $\endgroup$ – Mr.Mindor Jan 2 '18 at 21:10
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    $\begingroup$ I don't understand. I prefer not having my face at someone else' backyard while working, with or without clothing. But even if there is a noticable difference, the premise to assume that a posture like in the image is The Natural Thing To Happen is wrong. If people offend stuffing their face at someone else' poophole, but only while naked, then such an image would not evoke in the first place. Also, in societies or groups where nudity is the norm, there's typically not poo, pee and stink everwhere. Furthermore, despite clothes, medieval cities and even modern people often enough stink like f** $\endgroup$ – phresnel Jan 3 '18 at 11:52
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    $\begingroup$ Ignore the amount of people in the photo. Look at all the things to bash, scrape, snag, and otherwise catch against. Let your clothing take the impact; your skin is spared. It's the whole-body equivalent of a pair of work gloves for such an untidy environment. $\endgroup$ – flith Jan 3 '18 at 12:05
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    $\begingroup$ The only thing I see in this photo is I can't work out if the woman is doing "thumbs up" or "thumbs down." $\endgroup$ – Level River St Jan 3 '18 at 19:25

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