Laundry in Microgravity

The lack of laundry facilities in orbit was brought up recently and it occurred to me that  this lack seems to be more for lack of trying than real difficulty. The lack of trying that I suspect could be because it is more trouble than it is worth to wash clothes on the ISS when it is a relatively minor mass and volume is to just throw away the dirty and ship up more from time to time. Eventually with enough human activity in LEO and BEO though, the choices will be wash, wear dirty until worn out, make more on board, or ship increasingly large quantities of disposable clothing from Earth. I think option one will be desirable at some point.

The problems with washing clothes in microgravity as I understand it are more to do with the chemicals normally used in detergents than with mechanical problems. The chemicals from the detergents and most soaps are very unwelcome in a closed environment as any environmental contamination is a major issue. It’s not like the air conditioner is going to vent problems outside the laundry room.

To me, the likely solution will be more mechanical with plain water than the soaps and softeners we use here on the ground. Something along the lines of pressure cleaners allied with old style wringer washing methods.

laundryIn this cartoon, he dirty laundry is fed into the rollers on the left. The rollers seal the entrance and feed the clothing into porous chain that travels through the cleaning area where it is hit from both sides by staggered nozzles that are calibrated to have enough pressure to knock dirt loose from the clothing but not enough to damage it. The clothing exits the chain through a second set of rollers that squeezes  out most of the excess water and seals the exit from the rest of the ship.

During this the fluids in the wash area are continuously recycled through a liquid air separator/dirt filter/pump so that the same water is used indefinitely. This is represented by the oval in the lower section of the box. Second function of the filter/pump/separator is to maintain a lower pressure inside the machine than in the rest of the station so that there can be no contamination escape to the living area.

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I do construction for a living and aerospace as an occasional hobby. I am an inventor and a bit of an entrepreneur. I've been self employed since the 1980s and working in concrete since the 1970s. When I grow up, I want to work with rockets and spacecraft. I did a stupid rocket trick a few decades back and decided not to try another hot fire without adult supervision. Haven't located much of that as we are all big kids when working with our passions.

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13 Responses to Laundry in Microgravity

  1. ken anthony says:

    I think you’re over analyzing it John. A sealed chamber that evacuates and recycles a cleaning fluid should do the trick fine. Vibration would probably work better than agitation and rollers are not needed.

  2. john hare says:

    Could be Ken, as I said it’s more from lack of trying than actual difficulty.

  3. john hare says:

    There was an Innocentive contest some time back and one of the rules was no chemicals. Your cleaning fluid needs to be water or air Ken.

  4. Larry J says:

    Back in the mid 1980s, I read an article (I think it was in Aviation Week & Space Technology) about a NASA study to put a zero gravity washing machine in Space Station Freedom. As best as I could recall, the estimate at the time was that it would require several gallons of water per person per day to do laundry. The end result was that NASA would have to launch a dedicated Shuttle mission every few months just to deliver water to the space station. If you have access, check the AW&ST archives and you should find the article. When I read it, I knew then the space station project was in severe trouble.

  5. Johnhare says:

    I had assumed recycling the water almost indefinitely. Ill have to look into it when I get time.

  6. People really shouldn’t be living under– continuous– microgravity conditions for more than a couple of weeks, IMO. Its simply not healthy!

    So the solution to laundry in space is the solution to practically all the problems associated with microgravity. Long term occupation of space and long interplanetary journeys should be within rotating structures with large diameters that produce at least some significant levels of artificial gravity.

    Simple rotating space stations consisting of three pressurized habitats joined together by 100 meter long cables and twin light weight 100 meter long expandable booms should do the trick, IMO.


  7. ken anthony says:

    I was thinking perhaps steam, but wondered if that would weaken the fabric too fast? If we are living in space they have to be able to work with chemicals for any number of reasons (mostly industrial) or space will always just be a place we visit or move through.

  8. Peterh says:

    I’ve heard that supercritical CO2 makes a great dry cleaning fluid. Dissolves grease easily, then drops whatever it’s carrying when it shifts to gas phase with pressure drop. A “rinse/dry” cycle would then be to extract as much CO2 as practical from the wash chamber before the door was unlocked.

  9. N/A says:

    Idiot check idea, what about putting the clothes in a mesh centrifuge that can be set in an airlock, like the new Nanoracks ISS commercial airlock? Vacuum out and shake the clothes of the flaking dirt/grease and outgas any remaining residue. Though that ends up contaminating the microgravity environment outside…

  10. Paul D. says:

    It might also be worthwhile to consider cloth that is more easily cleaned, or more resistant to heat/steam. For example, fibers incorporating fluorinated compounds that dirt/organic crud bonds more weakly to.

    Beyond that, one could simply dispense with most clothing by turning the temperature up and the modesty down. 🙂

  11. AMS says:

    Most the discussion I’ve seen around the internet in the past months have focused on SCCO2 laundry as it then doubles as a good parts cleaner, doesn’t have consumables like detergent, has simple flash boiling to take care of separating contaminants from the working solvent, and the CO2 pressurization equipment can be shared with life support and manufacturing (if you’re trying to make CH4 for rockets or higher-order hydrocarbons for plastic). Also it’s a high TRL product already in use on the ground (though zero-g adaptation would need some work).

  12. Egad says:

    > Beyond that, one could simply dispense with most clothing by turning the temperature up and the modesty down.

    I’ve occasionally thought about the clothing problem on years-long flights and wondered about the minimal clothing option. However, that led me to a second-order wonder: would there then be a problem with shed hair and skin flakes (think what’s inside your keyboard now — ) that would otherwise be caught by clothing?

    Related to that, what happens to such shed material on ISS now? Does it just get caught by air filters? If so, how often are the filters changed/cleaned?

  13. Before deciding on nudity, read up on why underwear was invented. Detergents, per se, aren’t even necessary. Plain water is a decent solvent. My wife uses a washer ball, which enhances mechanical agitation. And there are things like soap nuts, which grow on trees, and are sort of edible, though they taste pretty bad. Space flight means you have to treat gray and black water anyway. Just don’t use things that won’t naturally be in black water.

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