Laundry

RobertDyck · 2015-04-16 12:30:21

Space laundry. Yup, washing clothes in space. Currently NASA ships up new uniforms for astronauts on ISS. I notice it isn't always the blue NASA coverall, they appear to wear normal clothing. But NASA sends up new clothing, they wear them without washing until too stinky, then throw them in the garbage. This is particularly an issue for Mars, because a Mars mission is over 2 years long. You can't send up new clothes every few months.

Mars:
I propose an RV washer-dryer combo. Most houses have separate appliances: clothes washer and dryer. Apartment units are smaller, but still two separate units. A unit for an RV is one single appliance, about the same size as an apartment front-loading washer, but the single drum acts as a dryer. That is compact for RV use. It also uses 12-volt DC power, commonly available on an RV. A front-loading washer uses less water; another feature you want on Mars.

This will require a couple modifications. You want to reduce launch weight. The outer casing for the appliance could be aluminum alloy, but the drum must be durable enough to withstand clothes tumbling without the drum getting dented or warped. Should we use aircraft grade titanium alloy? Or something else? And the power must be compatible with the Mars spacecraft power systems. ISS uses high frequency AC power, not the 60Hz common in North America.
Here's an example: (click on image to see manufacturer's website)

One application is to wash an MCP spacesuit. Apollo astronauts found contamination was an issue, so expect Mars to be similar. One advantage of MCP is that it's machine washable. So here's the machine to do it.

Another issue is dryer venting. Expect fines to contaminate a spacesuit. So this will require filtration. One option is to bubble dryer exhaust through a tank of water, then periodically filter the water. Final exhaust will have to go through a HEPA filter. The water should remove most contamination, extending life of the HEPA filter. Final exhaust will vent into the Mars habitat, so air must be clean.

ISS:
This will have to operate in zero-G. The Mars device will have Mars gravity. If artificial gravity fails en-route to Mars, then astronauts will have to wear stinky clothes until they land. It would only be a few months, and that's contingency in case of artificial gravity failure. But ISS has zero-G all the time.

Front-loading washers use less water than top-loading, but they work with gravity. A front-loading washer uses the drum to pull wet clothes out of soapy water, then dip them back in. This moves soapy water through the clothes, washing them. But doing this in zero-G requires artificial gravity. This means a slowly spinning drum for washing would have to be within a faster spinning drum to provide centrifugal force for artificial gravity. The inner drum has to be off-set, not centred, for the washing drum to work. That means a deliberately unbalanced drum. That would cause vibration. On Earth, a top-loading washer with an unbalanced load will "walk" during the spin cycle. You don't want that in ISS. So can a washer work without artificial gravity?

A top-loading washer uses an agitator to move water through clothes. I propose that for ISS. The spin cycle of the drum willl drain water from the drum. Normally a top-loading washer drains water first, then spins to remove more water. The one on ISS will have to spin while full, to drain then spin dry. Some laundromats have a separate appliance with is nothing but a top-loading centrifuge to spin dry. This uses less power than a dryer, and spins clothes dry faster. That can be used before the dryer, reducing time and quarters for the laundry machines. The washer for ISS would spin at the normal rate of a top-loading washer, then increase spin rate to a laundromat centrifuge.

When finished, the laundry would still be damp. That requires a clothes dryer. A dryer works by tumbling to fluff clothes. That requires the drum to rotate so slowly that gravity pulls closes down, they don't stick to the drum at top of rotation. But it does require rotation. One option is again, a drum within a drum, and the inner drum has to be off-set. But rotating slowly enough that it doesn't cause vibration problems for ISS. Another option is air currents. That is a drum that doesn't spin. Let clothes float in zero-G, and currents of warm air blown at an angle to create a rotating current within the drum. This should blow the clothes around. So air nozzles in the walls of the drum, all angled in the same direction (clockwise or counterclockwise), and an air intake at the centre of the drum. So a zero-G clothes dryer. This would most likely be a separate appliance from the washer.

Dryer exhaust would go through the cabin dehumidifier. Or would have it's own dehumidifier before exhausting to the cabin.

Earth Return Vehicle:
I have proposed a reusable vehicle to travel from ISS to Mars orbit and back. Such a vehicle could use the same equipment as ISS. However, the Mars Direct mission plan has a much smaller ERV. It's basically a Dragon capsule. That has very limited space, but still requires 6 months to get home. Space will be extremely limited. One option is a camping clothes washer. Example:

I tried to find one that has wash and spin-dry in one tub, and the outer casing is almost the same size as the spin basket. A tiny basket in a large appliance would defeat the point. The ERV wouldn't have a clothes dryer, just a clothes line where the cabin dehumidifier fan blows.

Last edited by RobertDyck (2015-04-17 18:40:45)

RobS · 2015-04-16 14:07:55

Robert, couldn't you spin the clothes and the water settles out of the spinning drum into a water storage space outside the drum, then you use air to blow the water back into the drum (maybe through a spigot along the axis) and onto the clothes; then you spin the clothes again to force much of the water out of them, then repeat. That would be easier, it seems to me, than two spinning drums.

RobertDyck · 2015-04-16 15:24:10

You could. The conclusion I came to was a single drum, like a top-loading washer. Just use an agitator.

SpaceNut · 2015-04-16 16:28:26

I would try thinking more like a dishwasher in a 0g application where the water is sprayed from the center towards the rotating clothing with it changing direction of spin to create agitation of the clothes. The water would adhere to the clothes in the spinning motion trying to pass through the clothes sending it towards the outer part of the drum. This could work for either top or side load as the centrifical force would send the clothes towards the drum compressing them against the side wall. Add a suction on the outer wall to pull the water back towards the pumping unit to send it back into the sprayer.

Terraformer · 2015-04-17 08:12:33

So what's the plan for cancelling the torque? Would you have two different washers, attached to each other but running in opposite directions? It seems a waste to have to spin up a large flywheel to maintain a net torque of zero, when you can use a much smaller one and double the amount of washing.

In what ways can it be designed to help pump the excess water away to the holding tank? A screw shaped outer drum? A cone shaped one?

louis · 2015-04-17 09:11:42

Mass is an issue.

The simplest solution is to hand wash in a plastic bowl.

They could probably manufacture soap on Mars, so after a while would be no need to take detergent.

I did also read about a washing machine that uses something like plastic balls to clean off dirt.

GW Johnson · 2015-04-17 09:13:36

What y'all are discussing is developing new technologies and equipment for this deep space trip. Most of this new equipment development could be entirely avoided if you did the deep space mission planning on spin "gravity" from the outset. Then all you need are lightweight versions of the very same equipment and processes we use down here, plus what we already do for short time stints in zero-gee.

If you keep the zero-gee intervals fairly short, you can just wait to do your laundry, you can queue up at a few zero-gee toilets, and you can eat camp food. Otherwise, conventional laundry, ordinary sanitary facilities, and conventional free-surface water cooking are the norm while spinning.

Why do things the hard way if you don't have to?

And there is the "new technology development" effect: if your flight vehicle prove-out program incorporates brand new technology developments as critical items, it is very likely you will never fly. That's been the history of government-funded work for decade upon decade now.

What newcomers to the industry like Spacex and some others are doing is the exception that gives hope, but only as long as they are not fully dependent upon government-funded work. There's something enslaving about that, that kills all major accomplishment potential. We've all seen it.

GW

RobertDyck · 2015-04-17 09:52:49

On ISS the priority is to clean human sweat and skin oil. That requires a surface acting agent (surfactant). Only two categories of surfactant: soap or detergent. NASA already developed hand soap compatible with their water recycling system. Laundry detergent could be based on that.

Mars: a science mission would bring laundry detergent. A permanent settlement can grow an oil seed in a greenhouse. A simple expeller can press oil from canola, sunflower, safflower, cotton seed, or soybean. There are other soil seeds, but I suggest soybean. Soy is a major protein source, most meat substitutes are soy based. Since a permanent settlement will need soy anyway, produce soybean vegetable oil. Soap is made with either rendered fat with lye, or vegetable oil with lye. Lye can be sodium hydroxide or potassium hydroxide. NaOH produces a hard soap (bar) while KOH produces liquid soap. There's more to it, but you get the idea. A hard bar is difficult to make without a tree oil, like palm or cocoanut. So liquid laundry soap?

Sodium hydroxide is made by electrolysis of salt dissolved in water. Electrolysis across a membrane. Salt or thick brine goes in the tank on one side of the membrane, sodium hydroxide accumulates on the other. Hydrogen gas bubbles off one electrode, chlorine gas bubbles off the other. You burn those gasses with each other, done in a chamber with no oxygen. That produces hydrogen chloride gas, which dissolves in water to form hydrochloric acid. Necessary for various industrial processes.

Last edited by RobertDyck (2015-04-17 11:45:37)

RobertDyck · 2015-04-17 12:23:13

Terraformer wrote:

So what's the plan for cancelling the torque? ...two different washers ...running in opposite directions?

Ok

In what ways can it be designed to help pump the excess water away to the holding tank?

Rotating drum creates centrifugal force. That creates pressure. Outer drum has a hose from the outer edge to the holding tank. Fluid flow.

kbd512 · 2015-04-17 12:38:58

GW Johnson wrote:

What y'all are discussing is developing new technologies and equipment for this deep space trip. Most of this new equipment development could be entirely avoided if you did the deep space mission planning on spin "gravity" from the outset. Then all you need are lightweight versions of the very same equipment and processes we use down here, plus what we already do for short time stints in zero-gee.

There's no way to guarantee artificial gravity.

GW Johnson wrote:

If you keep the zero-gee intervals fairly short, you can just wait to do your laundry, you can queue up at a few zero-gee toilets, and you can eat camp food. Otherwise, conventional laundry, ordinary sanitary facilities, and conventional free-surface water cooking are the norm while spinning.
Why do things the hard way if you don't have to?

If artificial gravity generation fails, then what? What's the contingency plan?

GW Johnson wrote:

And there is the "new technology development" effect: if your flight vehicle prove-out program incorporates brand new technology developments as critical items, it is very likely you will never fly. That's been the history of government-funded work for decade upon decade now.

An interplanetary transfer vehicle is new technology, something that's never been built before. The requirements for travel to another planet with a trip duration of months is something that's never been done before. New technology is simply required or we're not going. NASA has stated that repeatedly and it's a valid point. The only question is whether or not what they're doing about it will lead to cost effective solutions delivered in a timely manner.

The history of cost plus contracts let by the government are expensive and poor solutions or lots of money spent with nothing to show for it. You can't put any government contractor on a cost plus contract and expect them not to run up the cost of the contract. If there's no financial incentive for the company to come up with a cost effective solution in a timely manner, expect poor performance.

This is NASA we're talking about, fer cryin out loud. If they can't build a washer/dryer combo that works in zero-G or hire someone who can, they need to be de-funded post-haste.

I'm of the opinion that NASA needs to be responsible for development of CL-ECLSS, clothing, cleaning supplies, and human habitation requirements for space. There's no existing commercial or military application for these technologies. This is simply something that the NASA will have to hire people to develop (something it has already done).

GW Johnson wrote:

What newcomers to the industry like Spacex and some others are doing is the exception that gives hope, but only as long as they are not fully dependent upon government-funded work. There's something enslaving about that, that kills all major accomplishment potential. We've all seen it.
GW

Dependency on government work for contracts is not enslavement and doesn't guarantee failure. The contractors involved and their government overseers need to have personal integrity and an overriding drive to produce cost effective solutions that actually work. A company making American cheese because Americans want American cheese is not enslavement.

RobertDyck · 2015-04-17 12:43:50

GW Johnson wrote:

What y'all are discussing is developing new technologies and equipment for this deep space trip. Most of this new equipment development could be entirely avoided if you did the deep space mission planning on spin "gravity" from the outset.

Very true. Convincing NASA to do that is an issue. My mission plan does that, but I keep trying to accept other ideas.

And there is the "new technology development" effect: if your flight vehicle prove-out program incorporates brand new technology developments as critical items, it is very likely you will never fly.

If we comply with that, we'll never go anywhere. I have to hope NASA (the new technology agency) will once again develop leading edge stuff.

GW Johnson · 2015-04-17 14:41:43

NASA should always be involved with new technology development. That's been their charter since they were NACA not NASA. Their proper role in that arena is to identify things needed, and then fund development of solutions.

Developing a flight vehicle is an entirely different arena. In that one, you pick stuff that is ready when you start design, and you develop your vehicle hardware around that. That approach served well with Mercury, Gemini, Apollo, and shuttle, as well as a variety of experimental lifting bodies. Violating that approach served very ill with X-30 and X-33.

I have no clue why NASA is afraid of providing artificial gravity, and why so many think they are correct to shy away from it. It is as illogical as not developing MCP spacesuits. Makes zero sense to me. We have known since Salyut 6 that 1+ year in zero gee is pretty much the limit. There is no exercise regimen to circumvent that limit, not anything discovered in all the years since Salyut 6.

And that only counts bone density and circulatory effects. We have since identified vision and immune system effects, and exercise appears ineffective with both. No telling what else will crop up in the Kelly twins experiment just getting underway.

A one-way trip to Mars is but 6 to 8.5 months. But, you simply cannot count on Mars 0.38 gee to be sufficiently therapeutic, precisely because we NEVER EVER did the partial gee experiments in orbit! Period. End of issue. Traceable to bad policy and management decisions. But there we are.

A Mars round trip is 2.5 to 3 years, with 1+ spent at no more than 0.38 gee. So, because of where we are vs where we should be, you MUST simply plan on providing artificial gravity, or else plan on killing your crew with a circa-10-to-15 gee reentry when the they come home. Period. End of issue. There is NOTHING as expensive as a dead crew, as NASA has learned to its chagrin.

Since we need to make some decisions in the next 5 years for a mission in the 2030's, my recommendation would be: highest-priority is some experiments in orbit with spin gravity adjacent to the ISS, using it as a base. Any agency serious about sending men to Mars after 2030 would already be doing this.

I take the lack as prima facie evidence that NASA has no intention to send men to Mars sometime after 2030. Look at what management does, not what they say. Words are worthless indicators. From agency and corporate heads, as well as politicians. And foreign dictators. We've seen this shtick before, for centuries.

As far as I am concerned, I have a lot more hope in private agencies sending men to Mars in the 2030 time frame than any government agency on the planet. Outfits like Spacex (and possibly ULA, if they decide to do stuff outside of government contracting) can supply launch vehicles of sufficient capacity, reusable or not. Outfits like Bigelow can supply versatile, adaptable module designs that can be assembled into any cluster we need for any mission, and rather quickly, if the customer isn't too stingy. Outfits like XCOR can supply reliable, safe, long-life rocket engines that truly fill the niche we are going to need for reusable craft, again rather quickly if the customer isn''t too stingy. (Which they have been.) Etc.

I'm sorry, but NASA business-as-usual as we know it today will never send men to Mars. It is nothing like what NASA did in the 1960's. There must be change, back to that early model. That's the judgement of an old aerospace industry rocket/ramjet/flight equipment engineer who began working with government labs in the contracting business 40+ years ago. I've seen enough of this BS in my lifetime to know and understand. Trust me. I know whereof I speak.

GW

Last edited by GW Johnson (2015-04-17 14:55:14)

Terraformer · 2015-04-17 15:06:58

Talking of Bigelow... I think there actually *is* a commercial market for zero-G laundry machines, or rather, there's a good chance there will be one in the next decade.

I can't see any reason why it would be really expensive project, either. I think this is the sort of stuff that space advocates should be working on.

kbd512 · 2015-04-17 18:11:57

I think NASA's fears of artificial gravity date back to the Gemini-Agena docking experiments. They're afraid of killing the crew because of a thruster or motor gone haywire. Back then we had no empirical knowledge of what we were doing because we were doing it for the first time. Times have changed and technology has improved.

I provided a lightweight proposal, relative to the mass of a rotating inflatable, for artificial gravity to permit the crew to spend their rest periods at 1G while simultaneously permitting the use of electric propulsion without the need for constant course corrections or thruster alignment with the direction of travel. Rotating the entire vehicle may be fine for cooking, cleaning, laundry, and other chores, but it means impulsive burns with chemical rockets because we never developed nuclear rockets or continuous thruster alignment with the direction of travel if we're using electric propulsion. From a propulsion standpoint, neither of those solutions are optimal.

One would think that a zero-G washer/dryer would be a higher priority item than an espresso machine, but good coffee's pretty important, too. Personally, I find nasty clothes to be far worse than plain black coffee.

As it pertains to making the unit light enough for space, I would think a titanium drum is the way to go. The number of ounces shaved off an already lightweight unit is unimportant compared to how durable the unit is. If this unit malfunctions during the trip because we decided to be overly clever in how many ounces we saved, it may cause actual problems for the mission.

Tom Kalbfus · 2015-04-17 18:49:51

Hard to tumble dry something in zero g conditions, you see the clothes tumble because there is gravity. One way to dry clothes is to expose them to a vacuum and the water boils out, that might work!

RobertDyck · 2015-04-17 20:09:15

Vacuum. Hmm. Might work. The idea I came to was a drum that doesn't spin, instead jets of air oriented the same way, and intake at the drum hub, both in the door and back of the drum. Perhaps at the top and bottom, a jet pointing into the drum rather than tangential, to cause clothes floating in zero-G in the spinning air to tumble. And to ensure clothes don't follow the drum surface, to actually tumble.

One could freeze dry clothes, which works best with vacuum. The following chart is from Wikipedia.

In a typical phase diagram, the boundary between gas and liquid runs from the triple point to the critical point. Regular drying is the green arrow, while supercritical drying is the red arrow and freeze drying is the blue.

Depends how fancy you want to get. This chart implies freeze drying requires dropping both pressure and temperature below the triple point of water, so below 6.12 mbar @ 0°C. What will that do to clothes? Would it harm fibres, reducing life of the clothes? Would it produce hard, crunchy cloth? One advantage to traditional mild heat fluff clothes dryer is that it fluffs the fabric.

RobertDyck · 2015-11-22 16:48:21

Started thinking about this again. One issue is how to work in zero-G, on ISS. Designing for artificial gravity in a habitat in transit to Mars is easy. In gravity on the surface of Mars is also easy. In both cases, just modify an existing RV washer/dryer combo. Modify to reduce weight, compatible with spacecraft power, compatible with water recycling. That means an aircraft grade titanium alloy for the drum, and appliance case made of either aluminum alloy, or plastic, or some combination. But we have to test stuff on ISS first, and ISS doesn't have artificial gravity. I mentioned the idea of putting the drum in a centrifuge. That is basically a larger drum, with the smaller washer/dryer drum about half the diameter so the top of the inner drum is the centre of rotation of the outer centrifuge drum. However, that results in a large device. How do we make it small?

Could we use air instead? That is a single drum, but at one point in the rotation a high velocity air nozzle pushes the wet clothing away from the surface of the drum. Centrifugal force will push clothing back to the outer wall of the drum, but as it rotates the clothing will pass the air nozzle, which will push the clothing back into the interior of the drum. This especially works if the drum has active air flow through perforations in the drum. Most dryers work with air through the centre of rotation in the back, and out through the door in the front.

But this is a washer/dryer combo, so the drum requires perforations for the water anyway. What if air is drawn out through those perforations into the outer drum, and into the dryer exhaust duct? This would use air flow to help draw clothes to the drum. But one point in rotation air flow is reversed, the high speed air nozzle. So we don't need perforations in the back, or the door.

In washer mode, it would operate like a top loading washer, with agitator. Because gravity doesn't exist, so can't pull clothing down from the drum. The spin cycle would create centrifugal force to push water out. It would still be front loading, but because it's in space there is no top or bottom. A front loading washer can operate as a top loader. This also means the agitator will be connected to the back of the drum, at the centre of rotation. Dryer air flow through perforations in the circumference of the drum means we don't need perforations where the agitator goes. So this is compatible.

As previously mentioned, torque this would apply to the station can be cancelled by operating two washer/dryer machines at the same time, with counter-rotating drums. The machines would have to be coordinated to run exactly the same cycle at exactly the same time.

Freeze-drying clothing can harm fibres, reducing their life. A normal washer/dryer should be more gentle to clothes.

Terraformer · 2015-11-22 17:06:54

Can't you just use a spin dryer for the dryer machine, and then use something else (a glorified hand/hair dryer?) to finish the drying? That would seem to be much simpler...

SpaceNut · 2015-11-22 20:17:12

Agitator vs. Impeller Washing Machines images of agitators and impellers

The Agitator style washer uses lots of water to have the clothing float within it in order for the agitator to mix/ stir the clothing to make the dirt fall out of them. In 0g the drum that holds the clothing will need to be a pressurized unit that forces the water back into contact with the clothes for the agitator to do its job. The inner drum and outer would both need to be sealed seperately to make the design work, with the inner drum being slightly small than the outer to allow for spinning of the inner drum for water removal. The inner drum would have holes for that water to pass through but I can see that it needs to be a double walled unit that allows for channeled air of high pressure to pass out into the drum through seperate sets of holes in the drums wall. A vaccum could recover the remaining water form the inside of the drum when the high pressure air is injected to push the clothing off from the drum.

RobertDyck · 2015-11-22 21:57:58

True, an agitator requires more than front loading high efficiency washing machine. But front loading machines on Earth work because gravity draws water down, while the drum pulls clothing out of the water, then lets it fall back. That makes maximum use of minimum water, which sounds good on ISS, but gravity is the issue. As I said, one option is an outer drum for artificial gravity, with an offset smaller drum for the washer. But that's a very large machine, and spinning the entire washer would create vibration and torque.

SpaceNut, what you're saying is the drum has to spin while washing? To create centrifugal force to separate dirt from clothes? And spray water through holes in the drum in a similar way that I described air while drying? Ok. Then we don't need an agitator. A washing machine requires two concentric drums anyway for the spin cycle. My old Speed Queen washer that came with the house didn't have any holes in the inner drum, but it did still have 2 drums. The inner drum was slightly conical, the spin cycle produced enough force that water moved up the cone shaped drum, and spilled over to the outer drum. But that washer didn't last long, the motor failed. The service technician said replacing the motor and transmission would cost so much I should just get a new machine. I hate replacing stuff, but I had it less than a year at that point. The new machine has a perforated drum like all other top loading washing machines. The spin cycle uses centrifugal force to press water out through those holes. I've already described using those holes for the dryer, we could add a pressurized spray of water as well. Spray in at one point, drain out all others. Water is collected from the outer drum to feed the pump for the spray.

This also means the drum doesn't have to be completely full of water. The gap between the two drums does, and enough water in the inner drum to cover clothes. But the centre of the inner drum could be air. With wet clothes splashing "up" (toward centre of rotation) from the water jet. So this reduces water necessary.

With the exhaust air channel not in the door, but through the outer drum, that means the door could be transparent like a front loading washer. Seeing what's inside is good.

Sounds like we're converging on a workable design. It will require good water recycling. ISS will require a significant water reservoir, not just water in storage bags.

SpaceNut · 2015-11-22 23:43:08

I was looking for spinning water in a drum and Reversing direction on a spinning cylinder of water. Some more for being able to get the design to a final step.

Antius · 2015-11-23 13:09:38

On Mars, it should be relatively easy to wash clothes using S-CO2. Put the clothes in the washer with a few blocks of dry ice. Close the lid and heat above the super critical point (31C). The S-CO2 is a chemical free solvent. The ultimate dry cleaning. When done you can simply release to ambient Martian pressure, or better, cool the CO2 to 220K at drain it out and store for next wash as a saturated liquid. Yet another way that Martian conditions provide opportunities that don't exist on Earth.

RobertDyck · 2015-11-23 15:46:58

Oh, yea. Others have mentioned supercritical CO2. I keep thinking of objects here on Earth used on Mars, so a washing machine but small. However, ISPP starts with producing dry ice in order to extract CO2 from Mars atmosphere. We could use that for dry cleaning. Here's an interesting video.
https://www.youtube.com/watch?v=-gCTKteN5Y4

SpaceNut · 2015-11-23 19:29:43

Moist clothing coming in contact with the dry ice would freeze on contact and would be vary brittle to impact if any spinning occurs.
I have had some recent issues with my electric clothes dryer in that the lint built up around the motor that turned the belt that made the drum move. The motor would not turn and needed to be cleaned plus lubricated in the bearings in order to allow for free spin once power was reapplied. So having a double moving drum removes this issue from the drying function.

RobertDyck · 2015-11-23 21:37:47

Uh, the appliance we discussed would have an outer drum that doesn't move, an inner one that does. You want to spin the outer drum too? For centrifugal force to move water to an intake? The air and water nozzles discussed have to be non-moving, with the inner drum moving cross them. Perhaps with a water drain on the outer edge of the outer drum. The ISS toilet uses air flow to draw urine down, perhaps a similar system to draw dirty water from the non-moving outer drum. Spinning the inner drum will create air flow vortex in the gap between drums, and that rotation will tend to push water to the outer circumference of the outer drum. The last bit of water could be "slurped" by air flow. Then the dryer function will use warm air to dry clothes, evaporating remaining moisture.

On Mars, I had envisioned an RV washer/dryer combo. But as a few members have pointed out, we could use supercritical CO2. That would be completely different. Basically, it's dry cleaning. To turn CO2 supercritical requires 31°C at 73 atmospheres = 1,072.8 psi = 73.967 bar = 7,396.7 kPa. Operation will require the pressure vessel to be safe with something more.

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