I’m writing a story where mars with its current atmosphere is inhabited entirely by women wearing the “spacesuit” with the following features:

  • tight fitting,
  • heated shirt,
  • heated leggings,
  • full head oxygen helmet

Would this suit protect them enough for 1 hour on the Martian surface?

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    $\begingroup$ Comments are not for extended discussion; this conversation has been moved to chat. $\endgroup$ – James Nov 20 '18 at 17:51

There are proposals for skintight spacesuits. This link is worth checking out for a NASA concept of skintight spacesuit.

MIT had also developed their version of skintight spacesuit.

The MIT BioSuit™, a skintight spacesuit that offers improved mobility and reduced mass compared to modern gas-pressurized spacesuits.

Please note the MIT Biosuit is more than simply a heated shirt and leggings ensemble.

For future astronauts, the process of suiting up may go something like this: Instead of climbing into a conventional, bulky, gas-pressurized suit, an astronaut may don a lightweight, stretchy garment, lined with tiny, musclelike coils. She would then plug in to a spacecraft’s power supply, triggering the coils to contract and essentially shrink-wrap the garment around her body.

The skintight, pressurized suit would not only support the astronaut, but would give her much more freedom to move during planetary exploration. To take the suit off, she would only have to apply modest force, returning the suit to its looser form.

Now MIT researchers are one step closer to engineering such an active, “second-skin” spacesuit: Dava Newman, a professor of aeronautics and astronautics and engineering systems at MIT, and her colleagues have engineered active compression garments that incorporate small, springlike coils that contract in response to heat. The coils are made from a shape-memory alloy (SMA) — a type of material that “remembers” an engineered shape and, when bent or deformed, can spring back to this shape when heated.

The precursor skintight spacesuit was the Space Activity Suit. This was originally proposed back in the 1950s and 1960s. In 1971 the Annis report concluded that the concept needed more work, despite being positive about its utility.

There are a number of proposals for a suitable Mars suit.

Mars suit or Mars space suit is a space suit for EVAs on the planet Mars.4[5] Compared to space-walking in the near vacuum of low Earth orbit, Mars suits have a greater focus on actual walking and a need for abrasion resistance.4 Mars' surface gravity is 37.8% of Earth's, approximately 2.3 times that of the Moon, so weight is a significant concern, but there are fewer thermal demands compared to open space.[6] At the surface the suits would contend with the atmosphere of Mars which has a pressure of about 0.6 to 1 kPa (6 to 10 millibars).[7] On the surface, radiation exposure is a concern especially solar flare events, which can dramatically increase the amount of radiation over a short time.

The conditions faced by astronauts on the planet Mars are severe and any Mars suit will need to take those into account.

Again one of those proposals includes the MIT Biosuit.

The Biosuit is a mechanical counter-pressure suit, resulting in a body hugging form.[19] In this type of suit, the pressure would come from the structure and elasticity of the material, whereas with prior space-worn suits the pressure comes from pressurized gas, like a filled balloon.[20] The gas-pressure can make a flexible suit very rigid, like an inflated balloon.[20] (see also Space activity suit)

In conclusion, while the principle may seem sound a Mars consisting of heated shirt, leggings and an oxygen helmet is effectively inadequate for Martian conditions. A Mars suit along the lines of something like the MIT Biosuit will be required. Otherwise the astronauts won't survive long. probably, less than an hour. Sensible astronauts will make sure their Mars suits are suitable for planetary conditions. No simple heated suits will do.

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    $\begingroup$ The key point, I think, is that Mars' atmosphere is essentially 99% of a vacuum (or 0.01 ATM) - there is an atmosphere, but really not much. Humans need at least 0.16ATM of oxygen partial pressure to survive and function so the suit must be pressurized. You can't be rid of this requirement until terraforming projects can increase the ambient pressure to a suitable level (at which point thermal insulation and a SCBA (either open or rebreather) would be all that would be required). $\endgroup$ – J... Nov 19 '18 at 16:35
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    $\begingroup$ @WakeDemons3: If it squeezes virtually all of your skin, there's not much difference $\endgroup$ – Mooing Duck Nov 19 '18 at 18:14
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    $\begingroup$ @WakeDemons3 the suit would still completely enclose the wearer. The difference is, instead of an atmosphere inside the suit providing pressure and turning the suit into a stiff balloon, it's bungees and springs outside the suit, pushing the suit's fabric against the wearer, and the suit is still flexible. $\endgroup$ – Ghedipunk Nov 19 '18 at 18:55
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    $\begingroup$ Interestingly enough, they might want to wear normal clothes too; these suits will have to squeeze the entire body evenly, and with different pressure per body part (or the soft parts will be squished too hard or even pulverized), so it'll look like a nudist camp. $\endgroup$ – Hosch250 Nov 19 '18 at 19:33
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    $\begingroup$ @Perkins can survive without damage, perhaps, but I think after a minute or two of breathing from the proverbial firehose you'd very quickly grow tired of the extreme discomfort of stretching your lungs to near breaking with every breath. And at just 0.16ATM we're getting borderline for hypoxia - any significant physical activity would require more oxygen than that. Maybe with conditioning and Diamox supplementation you might make a very short duration breathing like this but I expect it would still be extremely unpleasant. $\endgroup$ – J... Nov 19 '18 at 21:33

If, and only if, the garments described are fully sealed to each other and sufficiently rigid to compensate for the low atmospheric pressure, otherwise the wearer would almost certainly bleed out along the edges. Full seal is also needed for internal atmosphere retention. They also need gloves and very serious boots, they can't expose any notable area of skin to the atmosphere, or lack thereof.

Heating is a yes and no issue with any suit designed for extremely low pressure environments as @Mołot noted in a comment while Mars is frighteningly cold the atmosphere is actually so thin that it acts as an insulator (which I hadn't previously considered); so while heating the suit, and especially taking care to insulate it from the ground (which will suck heat out of it relatively fast, which is where serious boots come in), is necessary so is making sure it can radiate enough heat at need. Depending on the activity level of the person in the suit body heat could kill them; if, for example, the suit is designed for a pleasant stroll and the occupant is running heat stress could kill them. The reverse is also true, sit around in a suit designed with the thermal outputs of heavy labour in mind and you'll freeze to death.

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    $\begingroup$ Just my two cents - as far as I remember reading, 1 square millimeter holes don't even cause bruising when exposed to vacuum. So it doesn't even have to really be a seal, if only it is tight enough around neck not to let air downward, and can put pressure on the body. Good zipper would probably do the trick. Or good Hook-and-loop fastener. $\endgroup$ – Mołot Nov 19 '18 at 12:34
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    $\begingroup$ There's no need for "internal atmosphere retention". Your thinking about spacesuits is so 60s, get on with the times, by next 60s mechanical counterpressure suits should be in use, and those are pretty much what asker described. $\endgroup$ – M i ech Nov 19 '18 at 14:33
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    $\begingroup$ Stop being absurdly Earth centric. We are talking about Mars. There's next to no atmosphere on Mars. On Earth you insulate from air because it can steal heat quickly. Martian atmosphere will probably have 100 times lower heat transfer (wild guess based on pure density air density difference). Suit made of skintight, thin, breathing fabric should retain close to body temperature with most significant heat loss being through evaporation. $\endgroup$ – M i ech Nov 19 '18 at 15:17
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    $\begingroup$ @Miech: Maybe I'm missing something, but water tends to evaporate very rapidly in a [near-]vacuum... $\endgroup$ – R.. Nov 19 '18 at 17:07
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    $\begingroup$ It's precisely because water evaporates at near vacuum that it won't be an issue on Mars. Vacuum is a great insulator, and human bodies are great at thermal regulation. As soon as someone sweats, the water boils away, taking all of the excess heat away very quickly. It doesn't stay around at the skin to freeze and conduct additional heat away... and there's little atmosphere to conduct heat away into, anyways. Once someone stops sweating, they stop cooling. Except through their boots, or anything else that's touching something else. $\endgroup$ – Ghedipunk Nov 19 '18 at 19:04

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