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Why Are Spacesuits So Heavy?



Imagine trying to fix machinery while you’re orbiting Earth, with the Sun pelting you with rays, space dust flying all around, and your only source of oxygen strapped to your back. That’s what astronauts on spacewalks experience, and they do it all in 280 pound spacesuits. Of course, thanks to a lack of gravity, weightlessness makes the cumbersome suits a little less problematic, but it’s still no easy task to maneuver in one. Why make them so heavy in the first place?



1. They contain life support, a water tank, and SAFER system.
Spacesuits need to do a lot of things, all in the name of keeping astronauts alive. Part of the spacesuit is a backpack containing a life support system that provides oxygen and removes carbon dioxide, a water tank to circulate water through tubes in a liquid cooling garment, and the SAFER system which contains thrusters to help astronauts get back to safety if they begin to drift too far away.

2. The materials have to protect against a range of dangers.
Lightweight materials just won’t cut it out in space. To protect against intense radiation, extreme temperatures, and rapidly accelerating space dust, thick layers and hard outer shells are required. Altogether, astronauts wear an undergarment layer, upper torso shell, lower torso, helmet, and extra-vehicular visor. Every piece is necessary to keep them safe.



3. They don’t weigh so much in space.
Remember that weight is a measurement of how much force gravity is exerting on something. So, on Earth you weigh more than you would on the Moon, as does a spacesuit. Less cumbersome designs may be created one day, but current spacesuits have done their job for quite some time and are likely to continue working far into the future.
 
Jan 27, 2021
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Imagine trying to fix machinery while you’re orbiting Earth, with the Sun pelting you with rays, space dust flying all around, and your only source of oxygen strapped to your back. That’s what astronauts on spacewalks experience, and they do it all in 280 pound spacesuits. Of course, thanks to a lack of gravity, weightlessness makes the cumbersome suits a little less problematic, but it’s still no easy task to maneuver in one. Why make them so heavy in the first place?



1. They contain life support, a water tank, and SAFER system.
Spacesuits need to do a lot of things, all in the name of keeping astronauts alive. Part of the spacesuit is a backpack containing a life support system that provides oxygen and removes carbon dioxide, a water tank to circulate water through tubes in a liquid cooling garment, and the SAFER system which contains thrusters to help astronauts get back to safety if they begin to drift too far away.

2. The materials have to protect against a range of dangers.
Lightweight materials just won’t cut it out in space. To protect against intense radiation, extreme temperatures, and rapidly accelerating space dust, thick layers and hard outer shells are required. Altogether, astronauts wear an undergarment layer, upper torso shell, lower torso, helmet, and extra-vehicular visor. Every piece is necessary to keep them safe.



3. They don’t weigh so much in space.
Remember that weight is a measurement of how much force gravity is exerting on something. So, on Earth you weigh more than you would on the Moon, as does a spacesuit. Less cumbersome designs may be created one day, but current spacesuits have done their job for quite some time and are likely to continue working far into the future.
i believe they will make them reasonably lighter
 
Dec 29, 2019
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I doubt spacesuits will survive in current form if 10 hour day jobs in space become a thing; I don't think there will be many of those, suiting suited humans rather than better serviced by machines. I think without power assist of some sort basic manual tasks will always be slow, hard work, with fine dexterity compromised, but if your suits are in effect robots you may as well use robots - or use other, probably sophisticated remote operation, which can be done from the comfort and safety of... an office on the space station, or then, it could be somewhere on Earth. It isn't a matter of preference; for going commercial having the least astronauts keeps costs down.

But assuming there is a place for humans working in spacesuits then it will be different suits for different purposes. Something for working outside, something different for working inside - in vacuum within a station, without the sun or radiation - and quick and easy one size fits all emergency suits, just in case. Different suits for different tasks.

For any kind of physical work you need anchoring to get leverage. Anchoring is too important to delegate to booted legs anyway ( and gloved hands are enough to move around in internal workspaces and outside you would would want rocket jets), so if it were up to me I would not have legs on the suits at all. I'd make use of freed up feet to work controls - perhaps flying the suit. I'd also include some internal space, enough to pull head back out of helmet and arms out of sleeves, to eat and drink and scratch and piss at least.
 
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Catastrophe

The devil is in the detail
Is it because lighter materials either do not have the strength to withstand the outward pressure, or are too permeable to breathable gases at that pressure? Is temperature variation with these variables an issue?

Cat :)
 
Jan 21, 2020
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a spacesuit is a tool. the more it's used the more efficient it can become.
I expect it to become more flexible over time.
 
Mar 2, 2020
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Imagine trying to fix machinery while you’re orbiting Earth, with the Sun pelting you with rays, space dust flying all around, and your only source of oxygen strapped to your back. That’s what astronauts on spacewalks experience, and they do it all in 280 pound spacesuits. Of course, thanks to a lack of gravity, weightlessness makes the cumbersome suits a little less problematic, but it’s still no easy task to maneuver in one. Why make them so heavy in the first place?



1. They contain life support, a water tank, and SAFER system.
Spacesuits need to do a lot of things, all in the name of keeping astronauts alive. Part of the spacesuit is a backpack containing a life support system that provides oxygen and removes carbon dioxide, a water tank to circulate water through tubes in a liquid cooling garment, and the SAFER system which contains thrusters to help astronauts get back to safety if they begin to drift too far away.

2. The materials have to protect against a range of dangers.
Lightweight materials just won’t cut it out in space. To protect against intense radiation, extreme temperatures, and rapidly accelerating space dust, thick layers and hard outer shells are required. Altogether, astronauts wear an undergarment layer, upper torso shell, lower torso, helmet, and extra-vehicular visor. Every piece is necessary to keep them safe.



3. They don’t weigh so much in space.
Remember that weight is a measurement of how much force gravity is exerting on something. So, on Earth you weigh more than you would on the Moon, as does a spacesuit. Less cumbersome designs may be created one day, but current spacesuits have done their job for quite some time and are likely to continue working far into the future.
You are confusing weight with mass. Spacesuits in microgravity can be cumbersome just moving the joints and especially using the gloves. It takes just as much effort to move mass as it does on Earth, a fact that was learned in the Gemini program when Gene Cernan struggled on his EVA.
 
May 14, 2021
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As a volunteer firefighter, I also contemplate fire or other disasters aboard these spacecraft. The ISS has had at least one fire, fortunately, it was handled with little issue. Problem is, that in case of a major mishap, it takes a very long time and a team to get just one person suited up. No such thing as a quick evacuation up there.
 
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Dec 29, 2019
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"form of tight material around the skin to keep the pressure at around 1atm."

Such as? That you would be prepared to test in space?

Cat :)
There have been serious attempts to do unpressurised spacesuits that don't hold in any air except around the head - Mechanical Counterpressure Suits. These wrap the body in tight, porous fabric that prevents expansion of flesh when exposed to vacuum and that is enough to prevent tissue damage.

Paul Webb made a series of prototypes, some that were successfully tested in vacuum chambers, for up to 2hrs and 45m. They worked, weighed less than then current spacesuits and were easier to work in but there were problems, notably getting in and out of them was an ordeal - they need to be very tight - and areas like groins were very difficult to tailor and if not right there can be fluid build up that probably gets painful if not damaging.

Other attempts have been done as well and I think could still be ongoing. The later MIT "Bio-Suit" used memory alloy coils to allow the suit to be loose for getting in and out. I expect it will take sophisticated active tension control to get constant "pressure" everywhere and that will give freedom of movement .

An example of one of Webb's prototype spacesuits (minus backpack) -

 
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May 25, 2021
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"There have been serious attempts to do unpressurised spacesuits " My emphasis.

But would you go into space dressed like that?

Cat :)
I wouldn't try it. Our skin has to breathe also, as with the rest bodies.
SCUBA diving wet suits? They still put a film of water between the suit and your skin. Which acts like an insulation, and water has oxygen in it. Fish breath that through gills.
 
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Clovis - One of the advantages is that these kinds of spacesuits allow perspiration to escape, ie they breathe. It allows normal cooling from evaporation of sweat - and keeping cool is a major issue. I suppose there is an ongoing loss of water that cannot be recovered.

Some layers keep the flesh in and prevent expansion. Other layers, where needed, can insulate.

Catastrophe - whether the retro look can be made stylish or not depends on how good the decorator/designer is.
 
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Dec 29, 2019
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Ken, my question was not fashion orientated.

Cat :)
If you can't trust equipment made and tested and approved for the purpose you shouldn't go to space. There are so many things that would kill you if they don't work as expected that being alarmed by the type of spacesuit seems an irrational fear. You could try in a vacuum chamber first to allay your fears - which might well be done with this kind of suit to be sure the fit is right.

I had a recent debate elsewhere about SpaceX taking passengers in a rocket that has no pilot - what if something goes wrong? But the reliability has to be there first to have a pilotless rocket - which has significant advantages. It isn't about the technology but about an inability to trust the equipment. If you want to go to space you have to trust the technology.

I think they'd be most appropriate for Moon or Mars, where there is gravity and the need to walk. I'm still inclined to compact work "pods" for serious zero gee work, as I said above -

if it were up to me I would not have legs on the suits at all. I'd make use of freed up feet to work controls - perhaps flying the suit. I'd also include some internal space, enough to pull head back out of helmet and arms out of sleeves, to eat and drink and scratch and piss at least.
 
Dec 29, 2019
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But would you go into space dressed like that?
As to whether I would be okay with wearing one? I don't have any problem with the idea that skin can be exposed to vacuum and that preventing expansion of flesh prevents damage; I think we could come up with simple experiments to show that the principle works - a strong vacuum cleaner with a firm mesh over the end sucking on a patch of skin should do it. The mesh can't be too stretchy - or flesh still expands and bulges into the nozzle under it, which is what the mesh has to prevent.

For such a spacesuit I'd probably feel better trying it in a vacuum chamber on Earth than going to space but not because of the suit. Sure, I'd be thrilled to have an opportunity to take in the views from orbit, with Earth the best view of all (will there be binoculars?) but I think it would be self-indulgent, serving no real purpose - and I was never a big fan of the vomit rides at amusement parks. I still think for most purposes machines do Space better than astronauts.
 
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Catastrophe

The devil is in the detail
Ken, for what it is worth, I understand that 1 atmosphere is 407 inches of water, and a good vacuum cleaner develops about 80-100 inches water. So that would make a vacuum cleaner operating at about one quarter atmosphere vacuum. I just don't know what the relative effect on each would be in terms of blood pressure acting on skin, as I am not a biologist. This is just for information purposes.

Cat :)

Addition: I think this is just what one needs to see. Exposure of body parts (hand, stomach) to a vacuum. Blood gets pulled through to the surface of the skin, inter alia.

View: https://www.youtube.com/watch?v=iWGGMchu6mQ
 
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I'm not sure what actual experiments were done to show it would work but they had to have been done - maybe not like what I proposed. But it isn't conjecture - there isn't any question the basic principles of mechanical counterpressure spacesuits are sound. If you could measure the volume of that hand you would find it rises in response to reduced air pressure and in vacuum it would blow right up. But if that hand was wrapped in a very tight glove, so the volume could not change, the blood wouldn't be drawn to the hand and done right that exposure to vacuum would be harmless and painless.
 
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Ken, sounds OK as long as fabric is continuous, viz, no spaces between "woven" fibres.

Cat :)
Well, the spaces need to be less than about 1mm according to the "puncture" tests Webb did. Undamaged the spaces within the fabrics are much smaller than that. According to the Wikipedia article -

Tests of punctures showed that up to a square millimeter of skin could be directly exposed to vacuum for extended periods with no permanent effect.
So larger punctures to the fabric than that should be survivable.

I don't know if they will be adopted - they would have to prove superior across various criteria to be adopted, including cost. So far they are superior in some regards but not in others. Surviving "punctures" - maybe that should be "tear" or "rip" - would be one of the areas where it is superior.
 
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Dec 29, 2019
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Ken, I am so pleased that you are convinced, But, personally, I would not go out without a proper space suit.

Cat :)
I don't have a problem understanding that a bungee cord will pull me up before the bottom of a deep canyon but I won't willingly do it. I don't expect I'd be afraid to put on a Webbsuit and go into vacuum - that it would be unsafe - but I'd prefer to observe it rather than experience it.
 
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