The pressure is still 1/3 of an atmosphere approx, regardless of mechanical or gas. The more salient question, to ask those who have experienced it, how do those parts of the body respond to less than normal atmosphere pressure. Sounds like that could be a 'sensitive topic' as well.
The human body manages fine with many times atmospheric pressure when diving, so a third less shouldn't really be much of an issue, though I would imagine that the oxygen levels would have to be kept very high at those sort of pressures. And is only the gas in the body that you really need to worry about, the liquids and solids aren't going anywhere.
Mount Everest is at 29000 feet, where the air pressure is 32 kPa [1], which is about a third of sea level's 101.325 kPa. People have climbed everest without supplemental oxygen, let alone a pressurized suit. I imagine that the body would be fine.
To be coy, it matters quite a bit to the respiratory system. But of course there's a face mask as part of the system. And that's what keeps the balloon inflated, if you will.
I think all of the trilogy had people using "walkers" on Mars that compressed bodies elastically rather than being pressurized - though they did have normal style helmets.
> Between 60 and 160 C, the coils contracted, pulling the
> attached threads, and tightening the cuff.
I have no background in material sciences, and I'm sure the researches thought of this, but couldn't the model have been reversed to expand under exposure to heat and have trained the contracted state? This way, electricity would only be required to enter the suit, and the steady state would require no external power or mechanism. This seems like it would be safer in a situation like extreme low pressure where any failure would be fatal.
Alternatively, the activation temperature could be lowered to body temperature, only requiring cooling to exit (or enter) the suit. As long as sufficient metabolism happens within, the suit would remain sufficiently pressurized.
Its been more than a decade since I was an undergrad Materials Engineering student (I didn't even graduate in in that field), but I think the answer would be the same as for any coil. It is easy to elongate a compressed coil through deformation, but it is much harder to compress an elongated coil through deformation (while preserving the coil's properties...you can definitely smash one into a ball quite easily, but it no longer acts like a coil). With SMAs, there aren't two memories, there is a memory and a non-memory state. The non-memory state is like any other wire, deforming with physical force. In order for your proposal to work, you would have to take an elongated memory coil, and then physically deform it into a compressed coil to get the contracted state. That is a lot harder to do than to take an elongated coil and return it to a compressed memory state.
I talked to a guy who toured SpaceX not too long ago, and he said that Elon Musk had a staff of designers making spacesuits that were more comfortable and stylish. He said that putting on a spacesuit should be as easy as putting on a tuxedo.
Wow, are you a detective? Sharp eye ...
Also, if anyone downvotes my previous comment in the next 5 minutes, you could win a genuine shrink wrapped space suit this article is about, Act now!
Plugsuit: "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."
Its an interesting note but it raises more questions than it answers. Sure SMA's contract when they heat, the robotics community has played with it as "muscle wire" for a long time (at least since the 90's), but in space its really hot, and then its really cold, and then its really hot, Etc. The difference in temperature between shade and sunlight is extreme. As the SMA doesn't care how its temperature changed, using it in such temperature dynamic environments is really really really challenging.
The second issue is that getting into and out of skin tight space suits is probably not #1 on the list. The issue is how do you bend your elbow? Even at 2 - 3 PSI, a 24" long sleeve (4" diameter cuff) has 650-975 pounds of force holding it "straight". That means you need a mechanical elbow joint which is both air tight and light which breaks the sleeve into two 'segments'. Astronauts get exhausted just opening and closing their hands while on EVA.
The group’s next challenge is finding a way to keep the suit tight. To do this, Holschuh says there are only two options: either maintaining a constant, toasty temperature, or incorporating a locking mechanism to keep the coils from loosening. The first option would overheat an astronaut and require heavy battery packs — a design that would significantly impede mobility, and is likely infeasible given the limited power resources available to astronauts in space. Holschuh and Newman are currently exploring the second option, looking into potential mechanisms to lock or clip the coils in place.
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[ 4.7 ms ] story [ 50.9 ms ] threadThe only gas to worry about, aside from carbon dioxide.
[1] http://www.wolframalpha.com/input/?i=air+pressure+at+29000+f...
Standard HN disclaimer: IANAMS.
"It's after 6pm, Liz. What am I, a farmer?"
The second issue is that getting into and out of skin tight space suits is probably not #1 on the list. The issue is how do you bend your elbow? Even at 2 - 3 PSI, a 24" long sleeve (4" diameter cuff) has 650-975 pounds of force holding it "straight". That means you need a mechanical elbow joint which is both air tight and light which breaks the sleeve into two 'segments'. Astronauts get exhausted just opening and closing their hands while on EVA.
The group’s next challenge is finding a way to keep the suit tight. To do this, Holschuh says there are only two options: either maintaining a constant, toasty temperature, or incorporating a locking mechanism to keep the coils from loosening. The first option would overheat an astronaut and require heavy battery packs — a design that would significantly impede mobility, and is likely infeasible given the limited power resources available to astronauts in space. Holschuh and Newman are currently exploring the second option, looking into potential mechanisms to lock or clip the coils in place.
(It's also book 3 of a series, but I can happily recommend the first two as well.)