# Environment suit design for ultra-cold temperatures

What would be the design of a near-future extreme-cold environment suit?

Consider a protective suit that is not a space suit because it doesn’t need to augment the pressure felt by the body. It does, however, need to protect against extreme cold. While the lack of pressurization makes a lot of things easier, the existence of an external atmosphere also means heat can be lost easily as the outside air touches the suit.

I figure the basic coverall will have no problem being more than insulating enough, using existing aerogel cloth.

Aside: when I first learned about aerogel cloth, I thought it would be awesome to make a pair of kitchen oven mitts that would be truly worthy — pick up a roast right from the oven (normal gloves will only last a few seconds; or worse due to the grease getting wicked up) and go straight to liquid nitrogen handling without any problem. But the smallest quantity I could find cost a thousand dollars. Now, I just did a search on Google for aerogel fabric insulation and one of the featured shopping links is \$19.00 on eBay (\$4/square foot). The product specs say you get R30.9 with a three-inch covering. In fact, here is a jacket that claims to withstand −321°F on the outside while the inside stayed at 89°.

I figure some kind of snowshoe or tall block under the foot will keep them safe against extended contact with the cold ground.

But I’m wondering about the helmet. A clear globe would not be made of a super-insulating material. Can it?

Should they have a clear globe as a secondary cover, and still wear a hat and breathing mask, as opposed to filling the globe with warm breathable air?

The use case is Antarctic winter as a prototype for a design that could work on Titan.

What design would you foresee for such a suit?

## For reference

South pole: temperature −52°C 7 feet above the ground; ground contact temp. can be as low as −92°C. Pressure is 0.65 atmosphere.

Titan: −180°C. Pressure is 1.45 atmosphere.

• Aerogel can be put between layers of glass, so a helmet made of two or three layers of glass with aerogel insulation between them should do. The main thing is to ensure the air entering the helmet is both temperature and humidity controlled to prevent fogging of the helmet. – Thucydides Nov 22 '17 at 6:55
• @Thucydides but then it would not be transparent. I suppose a vacuum between two layers would work, but there might be better ideas. – JDługosz Nov 22 '17 at 6:59
• Fogging is one reason I think a separate inner breathing mask would be handy. The exhaled breath will not cause the helmet air to become humid. – JDługosz Nov 22 '17 at 7:01
• I'm not really sure how useful aerogel would be for a long-term insulation solution. Aerogel is basically just air, so it would be like putting a layer of non-convective air between you and the environment. You'd still lose heat via conduction. The absolute best way to insulate yourself would be to create a layer of vacuum within the suit. The suit would still have to be supported via some internal skeleton, but having just a few contact points reduces the amount of heat lost to conduction. This would also solve the helmet problem, as long as you have vacuum-strong glass. – Phiteros Nov 22 '17 at 7:03
• -321°F is just about 77 kelvin. The boiling point of oxygen is a shade over 90 kelvin, and the melting point of oxygen is a little over 54 kelvin. That jacket was dealing with a temperature at which oxygen is not a gas. – a CVn Nov 22 '17 at 20:37

# Double glazing!

The ambient temperature on the surface of Titan means that having a bit of a draft between your jacket and trousers could well be fatal rather than merely uncomfortable. Safety precautions in such a situation suggest that at least one layer should be totally airtight. This means there is an option for a full helmet filled with warm breathable air.

It doesn't need to be a full clear globe, it only needs the forward arc to be clear for visibility. Double glazed with a vacuum between the layers of glass/polycarbonate or otherwise. Rigid aerogel can be used for the rest of the helmet. Most of the specified materials are highly flexible, the helmet should be of a close fitting type that moves with the head on flexible neck seals.

The need to have that airtight layer means no breathability in the suit, moisture controls would hence also be needed to prevent it turning into a sweat bath and as such would control fogging in the helmet as well.

The other key complex part of the suit is the gloves. Dexterous work is going to need thin gloves, but these may not keep the cold out long enough for prolonged exposure. I can see two potential solutions to this. Powered heating elements in the gloves1 or an extra layer of heavy outer gloves worn over the lightweight ones which are removed for short periods to work and then put back on when the work is completed, the maximum time limit reached, or a skin surface temperature alert is triggered. A combination of the two is also a possibility, but we're steadily increasing the load on the suit's power systems with the powered features.

1 Heated gloves are available for motorbikes

• Allowing the wearer to see out and look around just turning the head needs a larger transparent section. – JDługosz Nov 22 '17 at 10:49
• @JDługosz, large yes, but not total, head movement is only a forward arc, limited in all directions. You can decide how much peripheral vision to limit at the extremes, or, with advanced materials, have a flexible neck section and a helmet that moves with the head. – Separatrix Nov 22 '17 at 10:53
• @JDługosz you've just given me a vision of a man in a space suit wearing a woolly hat over his helmet because he's cold – Separatrix Nov 22 '17 at 11:06
• Those woolly hats the Canadians wear will keep your head nice and toasty on the surface of Titan. – Neil Nov 22 '17 at 11:14
• Mount a camera on the helm and feed the video to a pair of goggles. Now you don't need a transparent visor. – Carl Nov 22 '17 at 17:35

# The problem is your hands

The controlling factor is manual dexterity. The great advantage of humans is that their hands can do just about anything. However, the stay time of a human in -180 C with any gloves thin enough to keep most of our manual dexterity will be short.

If your humans can't effectively use their hands, or can't use them for very long, why would you want to send humans outside? At this point vehicles, with arms for performing tasks, either generalized or specialized, will be more effective. Of course, if you are going to be driving vehicles out in the cold, there is no good reason for operators to be in those vehicles, when they could be operated remotely.

# The environmental suit is a drone

Therefore, the environmental suit to be used on Titan is a remotely-piloted drone. As such the considerations of the question are not so important.

# Bring the tasks to you

The best way to keep humans doing the jobs that drones just can't do is to bring the thing that needs working to you. Build a garage and have the robots move anything that needs working on (such a broken robots) to the garage. It is a lot easier to repair a broken robot in a heated (at least, heated to 0 C or something) than in the harsh outdoors. If you are repairing anything too large to move, then you can replace large components all at once. Have a drone remove your weather sensor's entire processing unit and bring the broken one back to the (heated) base for repair.

If you are trying to analyze things in quasi-enviornmental conditions, you can still send the humans into the garage in a suit, but now that suit can be plugged into the wall so they can use gloves with built in heating elements or something. Being right next to your base of supply makes it much easier to work in those conditions for the long term by swapping out operators.

# This won't be a flexible suit

The temperatures under consideration are close enough to liquid nitrogen that we can consider them the same for most materials. Basically, how ever it behaves in liquid nitrogen is how it will behave on Titan.

The suit will need to be:

• Air tight to prevent heat loss due to convection.
• Aerogel layers to prevent conduction of heat.
• Heating elements to combat the inevitable heat loss. Matching powerplant/power cell to supply the required power.
• Rebreather system to keep the occupant alive.
• Moisture management system. Fremen stillsuits would be a good way to approach this.
• Have multiple layers of reflective insulation to prevent heat loss by radiation.
• Rigid outer skin to mitigate the effects of abrasion on the suit. A flexible outer layer probably won't work since most things at liquid nitrogen temperatures are very brittle. Brittle Zinc (video) and Brittle Plastic (video). Perhaps a very special flexible plastic could be found. Maybe.
• Rigid joints to prevent chips/drips of liquid/frozen gases from getting into the suit then sublimating to add extra pressure to the suit. Getting some liquid methane in your boots is going to give you a very bad day.
• By any means necessary prevent the collapse of the insulation layers between the body and the outer hull of the suit. Loss of insulation is lethal. If you think your bottom is cold when you lie in a hammock, this is just much much worse

# Vision

A triple or quadruple glazed helmet may be enough to prevent unacceptable heat loss. Each layer covered in heat reflective coating will help a lot too. The smaller the view port the better. Camera mounted to the helmet would provide visibility. It's up to the author whether these cameras would be primary or secondary visibility aides.

# Tool use

Given the rigid nature of the suit, the suit may not even have gloves. Instead, use some kind of hand analogue that the user controls from within the suit. For gloves with hands in them, the competing demands of keeping the hand warm (more insulation) vs maintaining dexterity (less insulation) may not be surmountable in this scenario. It's far safer to pull the hands as far away from the cold as possible.

# Emergency Procedures

Just as astronauts have emergency procedures should some aspect of their spacesuit fail, these cryonauts will need similar procedures. Heating systems fail. Electronics fail. Seals fail. Handling those failures is essential.

# Acceptance Tests

If this suit can keep a human alive and happy while submerged in a 2bar pressurized vat of liquid nitrogen for the duration of the expected excursions plus a 50 or 100% safety factor, then this suit will work on Titan.

• Heat loss in liquid is much higher than in a gas. Swimming in ice water is far worse than walking into air at that temperature. – JDługosz Nov 22 '17 at 20:12
• My point stands. If your suit can withstand the higher heat loss of a submersion in liquid then submersion in air should be easy. (Yes, you've probably over-engineered the solution but you are assured it will work). – Green Nov 22 '17 at 20:15
• carbon nanotube films and cloth stay flexible at liquid nitrogen temperatures., the outer layer could be made of it. – John Nov 23 '17 at 22:40

One of the biggest problems will be thermal regulation and sweat.

The amount of heat a human produces is highly variable. While doing nothing, you would dissipate about 100 watts. Strenuous exercise can dissipate up to 1500 watts for a professional athlete. it would be less for an average person, but we have to assume if your explorers are brave/crazy enough to explore the hostile environment you mention, they would train to have good fitness and endurance. Let's use 1kW as a maximum value. Also the base value of 100W will vary according to body seight, sex, person to person, and what the body is doing (digesting or not, etc).

Thus, the suit will need good thermal regulation. It will need to evacuate just the right amount of heat, but not too much!

When the user feels hot, he will sweat. Also we exhale water vapor when breathing. Thus the humidity inside the suit will rise. When humidity is high enough to no longer allow sweat to evaporate, things become really uncomfortable. It is possible to sweat buckets, and even get dehydration in 25°C, 100% humidity air if you exercise a bit. This is really important.

So, we need to regulate both temperature and humidity.

Polar explorers have trouble with this. Say the inside of the suit is at 25°C and the outside is -40°C. Sweat will evaporate, then the water vapor will travel through the insulation, and encounter decreasing temperatures. At some point, it will condense, then freeze, and the insulation becomes clogged with water and ice, and thus useless. This polar explorer says "frostbite is all about sweat".

So we have to keep the skin at a pleasant temperature, and prevent accumulation of water.

Suits for arctic conditions already exists. If you want to go on Titan though, or in other placer where the atmosphere is not breathable, you would have several options.

If the pressure is OK for a human and the atmosphere is not toxic (ie, no sulphuric acid...) then an oxygen mask plus an arctic suit should work. If the atmosphere has high levels of CO2 or CO or other gases that will knock you out in a few seconds, then of course, it won't work.

If the suit is airtight, then all the problems with humidity management become a lot worse. Some system would be needed to circulate dry air inside the suit, to regulate its temperature, dehumidify it (possibly recovering the water), etc. At this point you are looking at a spacesuit, minus the reinforcements intended to withstand pressure... Or maybe a light exosuit. Since it will require power and machinery it will be quite heavy, this having at least powered legs to help carry the weight would be a huge help in an environment with gravity.

If you enlarge the suit and make it a mech, then the user inside can be in a larger "pod" which no longer needs to be form-fitting, which solves all the problems with air circulation, moisture, etc. But it's a huge mech.

Note: in case of huge mech you need an emergency system to walk out in case it breaks down. This absolutely needs to be an inflatable hamster ball. Just because.

A wackier option would be to have the inside of the suit filled with warm water (except the helmet). Water is a lot better than air at transporting heat. It would probably feel quite awkward to walk inside a portable swimming pool, though!

But I’m wondering about the helmet. A clear globe would not be made of a super-insulating material. Can it?

No... Also you need the inside to be at a high enough temperature to make sure water vapor does not condense and/or freeze, in which case the user wouldn't be able to see anything at all (it isn't that easy to wipe the inside of your spacesuit helmet with your fingers...) This could be done with a transparent heating film on the inside of the helmet and perhaps a double glazing.

Your "suit" will be more akin to a small mech that is piloted than the Apollo/Skylab A7L space suit.

Outfitting one of the mechs from Avatar for extreme cold would allow the operator to work in a shirt sleeve environment, carry the megawatt reactor to keep everything toasty, and the tonnage of steel required to tie it all together. The "Mercury" class suit from the animated Starship Troopers is another good example.

Other than that, the aerogel, layers of glass, bulky insulation and Canadian touque (hat) that other respondents have given are still major parts of the equation.

• I see. The transposed letters didn’t help! I further improved the edit. Note that you should remove the .m in mobile links. Now suggest you add a link to Mercury suit for the benefit of those not familiar with the series. – JDługosz Nov 23 '17 at 5:29