Currently, the ISS is resupplied with fresh clothes from the Earth. I remember reading a report on NTRS stating that the requirements for fresh clothes proved to be much higher than expected.

Thus, several related questions:

  • Will it be feasible to put a washing machine into the ISS?
  • What kinds of challenges are there to be overcome (vibration isolation, energy budget, water disposal, contamination etc.)? Preferably with breakdown into types of COTS washers most suited for space operations.
  • Will the benefits outweigh the costs for LEO operations (impact on resupply budgets, clothes wear and tear, smell etc.)?
  • What about interplanetary missions (Mars, asteroids)? How could washers contribute to getting job done at lower costs?
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    $\begingroup$ This might just be the question posed here that most caught me off guard as a good question. Fantasic! $\endgroup$ – PearsonArtPhoto Jul 23 '13 at 11:13
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    $\begingroup$ If you want to spin-dry your clothes, prepare for the whole station to start rotating against your drier during the drying. ;) $\endgroup$ – SF. Jul 24 '13 at 15:12
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    $\begingroup$ @SF Yay gravity! $\endgroup$ – gerrit Jul 24 '13 at 21:07
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    $\begingroup$ @kurtnelle: If you provide energy for the spinning - Newton's 3rd law of mechanics in rotary motion. Of course when the laundry's done your station stops spinning too. $\endgroup$ – SF. Jul 25 '13 at 5:46
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    $\begingroup$ new relevant video: Did you Know: How Often Do Astronauts Wash Their Clothes in Space? youtube.com/watch?v=dgoB5KUHoCE $\endgroup$ – AlanSE Aug 9 '13 at 14:10

Methods of cleaning

Current washing technologies are mostly solvent based. Most normal "soiling" of clothing is a mixture of oils and salts (Both of which are products of sweat), and sloughed skin cells, often bound by those same oils. When one finds clothing irritable from extended wear, it's usually due to the effects of accumulated sweat and skin cells, and the bacteria that eat them.

Normal washing uses a mix of water (as a solvent) and a surfactant to bind oil to the water for more complete cleaning. The agitation is mostly to move the water and surfactant mix through the garment and its fibers.

Dry Cleaning uses any of a number of chemical solvents to remove the various oils, salts, bacterial and skin cells.

It is possible to use abrasive processes to remove skin and oil accumulations; it won't generally remove them from between fibers, but "sand-washed" is a viable option for extending the wearability of a garment short term, at the expense of long term damage to the garment.

Air-washing is also possible; the use of high pressure and temperature air can remove large portions of the cells and bacterial colonies. It can remove some of the salts and oils, as well.

Evaporative cleaning can also be used; this can be used to remove oils, but won't remove particulates between the fibers.

Thermal degradation is used for certain forms of cleaning. That is to say, you heat it until the biologicals break down. It's not generally conducive to clothing, but in combination with other techniques, can be used for enhancement of other methods.

Why not use?

Water? It's present. In theory, astronauts could rinse garments with extant systemry. The thing is, water and other fluids are not easily handled in microgravity (as the wringing a washcloth video shows). It's certainly useable for limited applications. It's best used for removing salts; salt accumulation is primarily an artifact of sweat evaporation in a high heat environment, and is almost a non-issue in space. Plus, water is a limited quantity.

Surfactant? Most laundry surfactants are contact irritants. A spill in station would be a major hazard. Further, water used with them requires different purification from normal. Some specific ones could be used, but again, the environmental risks due to breathing in the material make it a risk, as does the increased risks to the water purification.

Dry Cleaning? Almost all the chemicals are highly toxic.

Air-washing? Noisy, and requires particulate capture aboard station. Also, it's not highly effective.

Evaporative? Slow, doesn't remove particulates (including bacteria and skin cells, as well as crystalline salt). Plus, anything removed now has to be scrubbed from the atmosphere. But at least, given enough time, the bacteria starve.

Thermal Degradation is a heating issue - both for the garment and for the habitat. Heat management is a major part of spacecraft design.

If you're going to anyway...

A combined pressurized steam to recapture system, possibly followed by vacuum drying, might be a reasonable system.

Use of pressurized steam gets maximum use of both thermal and air washing, plus removes some salts and oils from even inside the fiber bundles of the fabric, for a minimum amount of water. It's also a reasonably small system; a tractor feed unit could be created that washes a shirt at a time with a tractor feed. It also is of limited hazard to crew.

Adding vacuum drying on a warm surface would maximize volitalization of remaining liquids.

  • $\begingroup$ Thank you very much, the design you have presented looks feasible and economical. $\endgroup$ – Deer Hunter Jul 24 '13 at 19:02
  • $\begingroup$ Good answer. Is there any research on this topic? I could imagine that some people at least thought about this for the ISS ... $\endgroup$ – s-m-e Jul 24 '13 at 20:07
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    $\begingroup$ ISTR there having been some mention of it by NASA, but mostly, it's grounded in discussions from the TravellerRPG boards - when you get a bunch of sci-fi realism nuts together, the pros and cons tend to get weighed heavily. $\endgroup$ – aramis Jul 24 '13 at 22:26

I decided to search through NTRS and found this: http://hdl.handle.net/2060/20130012684

Waterless Clothes-Cleaning Machine

This machine can be used wherever water is at a premium, or to minimize washing with water.

Lyndon B. Johnson Space Center, Houston, Texas

A waterless clothes-cleaning machine has been developed that removes loose particulates and deodorizes dirty laundry with regenerative chemical processes to make the clothes more comfortable to wear and have a fresher smell. This system was initially developed for use in zero-g, but could be al- tered for 1-g environments where water or other resources are scarce. Some of these processes include, but are not limited to, airflow, filtration, ozone generation, heat, ultraviolet light, and photocatalytic titanium oxide.

The machine has a chamber large enough to contain and agitate several articles of clothing, as well as a self-sealing door for insertion and removal of the clothing. The agitation and removal of particulate and volatiles in the clothes is done by airflow and some kind of agitation mechanism, possibly by rotating the chamber and/or alternating airflow and/or beater panels for the zero-g environment. Agitation in 1-g could be done with tumbling. One of the main purposes of the airflow is to remove particulate from the clothing and to deposit it into a filter where the particulate can be removed from the filter at the end of the cycle. This airflow can also carry ozone into the chamber to penetrate into the clothing to kill off bacteria and break down odorizing proteins or other organics. The chamber can also contain an ultraviolet light source to expose the agitating clothes to bacteria-killing wavelengths of light.

This light source could also expose a photocatalytic material such as titanium oxide, embedded coated on the interior of the chamber walls or on agitation mechanisms, to energies that would produce hydroxyl ions from the chamber humidity to aid in the removal of organic compounds from the cloth.

Heat could be introduced into the clothing chamber either by heating the airflow or by heating the clothing chamber directly using electrical heater strips on the chamber walls. The heat would aid in the killing of bacteria, breaking down proteins, and evaporating volatiles from the clothes. The airflow for this system could either be completely recycled back through the system or vented out, depending on the needs of the clothes cleaner’s surrounding environment. Airflow, ozone, UV light, and the heat can be controlled independently so each can be turned on or off without affecting the others to allow for the needs of the specific type of clothing or different types of soiling on the clothes.

This work was done by Glenn Johnson and Shane Ganske of United Space Alliance for Johnson Space Center.

A small bibliography on the subject:

Break-even point

Ewert, Michael K.; Broyan, James Lee, Jr. Mission Benefits Analysis of Logistics Reduction Technologies. JSC-CN-28324. 2013.

No clothing laundry system was assumed in the baseline model because a one year mission is likely not long enough for the benefits of laundry to significantly exceed the direct clothing mass.

(Which doesn't mean I agree with them.)


Good question, and this is not really an answer to your question I know, but it's too long for a comment. My reaction to reading it was (perhaps strangely) to wonder about even the necessity of clothes in space.

It seems to me that on Earth, we wear clothes for a number of reasons (some practical, others more cultural and traditional than any purely objective, rational reason):

  1. to protect our fragile bodies from weather (in space, aside from EVA, we should be able to absolutely control the weather so as to make it suitable for whatever needs or preferences we have)
  2. to protect our fragile bodies from getting caught in hazardous machinery (clothes would probably be required in space for this reason just as they are on Earth, but if this is the only reason to wear clothes in space, then it seems to me that we might be able to do with a minimum of clothes—maybe spandex shorts for males and a scarf of some kind for anyone with long hair—and thus minimize the need for washing them)
  3. to protect our modesty (this seems to be strictly cultural as several Earthbound cultures such as the Zo'é people have largely done away with clothing; we humans have shown ourselves to be one of the most adaptable species on Earth, so it seems to me that we ought to be able to adapt to space with regards to clothing too)
  4. Decorative (see modesty)

If the technical challenges of washing clothes in space are very demanding, then perhaps we should seriously consider creating a space-faring culture that has little or no need for intra-vehicular clothing. Extra-vehicular clothing would obviously still be required, but the high risk of EVA would seem to make for strong justification to minimize them, thus further minimizing the need for washing clothes in space.

Again, great question; very thought-provoking.

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    $\begingroup$ Why clothes matter: mixed gender crews; privacy of certain physiological phenomena; medical privacy; protecting from friggin' cold of a thin tin can which is called a spacecraft; absorption of sweat during exercise and maintenance work. $\endgroup$ – Deer Hunter Jul 23 '13 at 20:28
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    $\begingroup$ absorption of sweat: but much easier to wash the sweat from our bodies than our clothes, no? $\endgroup$ – Osteoboon Jul 23 '13 at 20:30
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    $\begingroup$ Some good points, @DeerHunter, but then again, in zero gravity, why would sweat "drip" anywhere (tongue only partially in-cheek). On the other hand, who says it would be zero gravity, right? We could always impose artificial gravity through spinning. $\endgroup$ – Osteoboon Jul 23 '13 at 20:45
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    $\begingroup$ @CopyrightX — assuming functioning envrinmental controls, activities strenuous enough to cause sweat are activities vigorous enough to fling droplets. Even the gentle wringing of a washcloth was sufficient to send a few stray droplets away. Most of the electronics aren't going to be much affected, but the bacteria will grow and generate odor and some noxious chemicals if sweat accumulates (much as a worn shirt from exercise period accumulates a stench if still damp from sweat over 3 hours in your gym locker... $\endgroup$ – aramis Jul 24 '13 at 8:46
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    $\begingroup$ Even if you can overcome issues such as modesty, temperature control, and protection of the wearer from hazards, I would imagine that clothing has a major role in capturing materials emitted by the wearer which might accumulate and eventually interfere with operation of various systems (e.g. sloughed off dead skin getting into electrical contacts). If I'm not mistaken, space crew generally seem to have most of their bodies covered most of the time, exposing only head and hands. Seems like remaining clothed and dealing with the laundry problem might have important technical benefits. $\endgroup$ – Anthony X Apr 20 '14 at 22:47

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