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#1 2020-06-28 02:57:23

LiveForever
Member
Registered: 2018-12-14
Posts: 3

MIT Mars Bio Suit

MIT Mars Bio Suit

Just saw it at the angry astronaut .

NASA EV suit is bulky, humongous, similar to apollo suits.

MIT Bio suit is slender, agile, easy repairable (duck tape equivalent).
Very compact.
In studies. Needs a lot of funding $$$$.

Youtube, the angry astronaut, 10 things NASA can do to help SpaceX.

Any coments?

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#2 2020-06-28 06:18:59

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

Dr Paul Webb did the initial work on Mechanical Counter Pressure (MCP) in 1967, published in the Journal of Aerospace Medicine, April 1968. Intended for lunar surface for Apollo, but wasn't ready in time for Apollo 11. He built a full-up suit, a test subject wore it in a vacuum chamber equivalent to 50,000 feet. Demonstrated on a treadmill, climbing a step ladder, and bending over with helmet on step ladder. It worked, but test subject found the tight fabric over his chest restricted breathing.
220px-Space_activity_suit.jpg

Second generation was for a NASA contract; contractor report submitted to NASA in November 1971. The second version used an air bladder vest over chest and upper abdomen, with lighter elastic fabric over those areas. The vest had a non-elastic fabric over the outside, so inhaling would squeeze the air bladder. To ensure constant volume, the air bladder vest was connected to the helmet with a hose. With constant volume, there was no restriction to breathing. Tested in a NASA vacuum chamber with hard vacuum.

The second generation suit also used pressurized boots, with a rubber air dam about the ankle. This simplified balancing pressure about the toes. Think of a telemark ski boot, with hinged ankle. Although ILC Dover has been working with boots that look like leather work boots.

I have given a presentation at a Mars Society convention where I suggested 3 hoses: one from vest to lithium hydroxide canister in the backpack, one from backpack to helmet, and one from helmet to vest. Each hose with a one-way valve. This would circulate air via breathing, so no fan required. As lithium hydroxide absorbs CO2, pressure would drop. Human metabolism converts O2 to CO2. As pressure drops, a simple pressure regulator would release O2 from a pressure bottle into the system. This means the astronaut could breathe even if the battery completely failed.

We invited Dr. Paul Webb to the Mars Society convention in 2005. He had video from 1967, high resolution and full colour showing the test subject on the treadmill. He explained that the 1967 version was made with cotton threads dipped in rubber. He hired Playtex, the same company that made women's girdles, to make the elastic fabric. His second version used a then high tech fabric that just became available: Spandex. His paper explained that heat control would be by sweat. Heat loss through insensible perspiration (sweating when you aren't hot) would lose less heat than an individual floating at rest in zero-G. So the individual would get warm, controlled by sweat. As the individual exerted himself to do work, he would get warmer, sweating more. A simple bottle of drinking water was the entire cooling system. I asked him whether the rubber air bladder vest would inhibit evaporation (or sublimation) of sweat to space. He said no, it "wicks" to the edges and evaporates there.

Ensuring even pressure required a plastic bag filled with liquid silicone over the genitals, up the crack of the ass, and the trough of the lumbo-dorsal spine. He thought bags of silicone would also be required in arm pits, palm and back of the hands, but his experiments showed they weren't necessary. At least at 3.3 psi, the pressure of his 1967 suit.

NASA intended Apollo to use 3.0 psi pure oxygen in the capsule, 3.3 psi in suits. That was before the Apollo 1 fire. After the fire, NASA changed to ambient air at launch, the spacecraft would bleed air during ascent. When the Apollo spacecraft finally settled in space, it had 5.0 psi pure oxygen. Yes, still pure oxygen. They didn't want the complexity of balancing two gasses. Skylab used 5.0 psi with 60% O2 / 40% N2. Apollo A7L and A7L-B suits used 3.7 psi pure oxygen.

In 1984 Mitch Clapp developed an MCP glove compatible with the EMU suit that NASA used at that time on Shuttle, and still uses on ISS. The glove was intended for construction of the space station. EMU uses higher pressure, 4.3 psi, so the glove had to be designed for that. At that pressure, bags of silicone were required over the palm and back of hand. It was tested in a glove box, with the box pumped down to vacuum. And the test subject reported it was uncomfortable until the box had vacuum. A high pressure glove when the rest of the body does not have the same pressure creates an imbalance. Advantage of the MCP glove is if it gets a pin prick, there is no damage, continue working. If there's a tear, the subject will get a bruise where skin is exposed to vacuum. With a traditional gas bag glove, a pin prick creates a leak. A significant tear could depressurize the suit quickly. The glove is comfortable, once in vacuum. Greater range of joint movement, and less counterforce to moving the finger joints. It wasn't used.

Dava Newman (inventor of MIT Bars Bio Suit) gave a TEDx talk on her suit. One point was developing a suit for 20 kPa is easy, developing one for 30 kPa is hard. 20 kPa (kiloPascals) = 2.9 psi. 3.0 psi would equal 20.684 kPa, so she rounded. 30 kPa = 4.351 psi. MCP uses 4.3 psi, so again she rounded.

Earth atmospheric pressure at sea level is 14.69595 psi (usually rounded to 14.7), with 20.946% oxygen. That makes partial pressure of oxygen at sea level 3.0782 psi (round to 3.0). This means anyone can breathe 3.0 psi pure oxygen. I have recommended Mars habitats use 2.7 psi partial pressure O2. Boulder Colorado has 2.54 psi partial pressure O2, so that's easy. Apollo before the fire wanted 3.0 psi in the cabin, 3.3 psi in the suit so a leak of 10% would result in O2 that astronauts were used to. Based on this same argument, a Mars habitat of 2.7 partial pressure O2 (plus nitrogen & argon), and Mars spacesuit of 3.0 psi pure oxygen. That means an MCP suit is "easy", to use Dava Newman's words.

Another engineer pointed out an MCP suit is machine washable. A gas bag suit is not. Apollo found the suits got filthy. A Mars expedition will stay many months, so a washable spacesuit is a great advantage.

Spacesuits have a thermal and micrometeoroid protection garment as the outer layer. An MCP suit would wear this as a parka and ski pants worn over the pressure suit. The outer garment for space or the Moon requires micrometeoroid protection; EMU uses OrthoFabric, which is a double layer fabric of 400 denier PTFE fibre fabric outside, with a backing of Nomex where 2 threads are replaced by Kevlar every 3/8", in both the warp and weave directions. Thermal protection is multi-layer insulation, which is multiple layers of aluminized Mylar separated by fishnet. The aluminum reflects radiant heat. This works very well in the vacuum of space, but not in air. With any air pressure, the aluminum will act as a heat sink. So this won't work on Mars.

Mars surface doesn't have micrometeoroids; they burn up in the atmosphere 30km above the surface. Mars does have sharp rocks. So therefor 80 denier PTFE fibre fabric would be more appropriate. That's the outer layer of parkas designed for Antarctica. And instead of multi-layer insulation, use thinsulate. That's the same insulation used for ski jackets and pants.

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#3 2020-06-28 08:16:57

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For RobertDyck re #2

It was ** really neat ** seeing your reply to LiveForever.

For LiveForever:  You've been registered since: 2018-12-14.  Thank you for bringing the Mars Bio Suit idea back into the present active topics!

It is time for an update since 2014, which is the date most citations Google provided seem to indicate there was a flurry of activity.

RobertDyck has provided a foundation for updates.  Would you be willing to do some investigating, and post the results in this new topic?

As the date when astronauts will head to Mars approaches, the need for suitable (well tested) garments increases.  The first likely opportunity for an expedition with human volunteers would be in 2022, but I admit that is on the optimistic side.

(th)

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#4 2020-06-28 08:40:45

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,841

Re: MIT Mars Bio Suit

Welcome to Newmars LiveForever. but what took so long to strike up a conversation....

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#5 2020-06-28 22:43:33

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

Spacesuits on ISS no longer use lithium hydroxide to absorb CO2. They now use silver oxide sheet metal. That's heavier, but can be thermally regenerated. That means bake-out the CO2. ISS uses a toaster oven to bake out cartridges. I have a NASA paper from the 1990s about using a microwave oven to do that. Shouldn't be a big surprise that the microwave oven is more energy efficient. However, the silver oxide has to be configured as granules instead of sheet metal.

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#6 2020-06-30 00:57:12

LiveForever
Member
Registered: 2018-12-14
Posts: 3

Re: MIT Mars Bio Suit

Will a 3D printed bio suit be posible?
Disposable?
Multilayer?
Recyclable?

Last edited by LiveForever (2020-06-30 00:57:52)

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#7 2020-06-30 01:03:53

LiveForever
Member
Registered: 2018-12-14
Posts: 3

Re: MIT Mars Bio Suit

Building the future spacesuit
dava newman is professor of aeronautics and astronautics and engineering systems at the Massachusetts Institute of Technology (MIT). She is also the director of the Technology and Policy Program and a Margaret MacVicar faculty fellow. Her expertise is in multidisciplinary research that combines aerospace biomedical engineering, human-in-the-loop modeling, biomechanics, human-interface technology, life sciences, systems analysis, design, and policy.

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#8 2020-06-30 01:52:02

RobertDyck
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From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

Hello LiveForever, nice to see you're still here.

Yes, I saw a PowerPoint presentation that Dava Newman gave to an all-male NASA audience. It included a cartoon depiction of a naked woman getting a biosuit applied in what looked like a shower. Uh huh. Well, um, no. the suit will not be disposable. The word "recyclable" means the it's still disposed, just with some effort to scavenge the raw material. Instead of making something that's disposable, how about something that works?

A Mars Society member who is an MD specializing in decompression sickness sent me a photocopy of Dr. Paul Webb's paper published in April 1968. I digitized it and posted on the local chapter website. It's in Word format here: The Space Activity Suit: An Elastic Leotard for Extravehicular Activity

Dr. Webb's November 1971 contractor report to NASA is here: Development of a Space Activity Suit

Dr. Dava Newman served as NASA deputy administrator. I hoped she would get a NASA MCP suit, but it didn't happen.

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#9 2020-06-30 07:19:03

louis
Member
From: UK
Registered: 2008-03-24
Posts: 6,300

Re: MIT Mars Bio Suit

Yes - at some point in the future would be my answer. Things like fabric and zips have already been 3D printed. Probably not practical in the short term, so the MCP suits would be imported initially. Just about anything is recyclable in some form but depends on the cost-benefit analysis. They might have maintenance overhauls - if the internal layers are good, you might just want to replace the outer fabric if that suffers a lot of wear and tear.

LiveForever wrote:

Will a 3D printed bio suit be posible?
Disposable?
Multilayer?
Recyclable?


Let's Go to Mars...Google on: Fast Track to Mars blogspot.com

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#10 2020-06-30 08:00:26

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For Louis re #9 

Your reply to LiveForever inspired a train of thought that leads me to offer a new word for the English language:  nanoprint

So (naturally) I asked Google if the word is in use, and it not only ** is ** in use, but those who are using the word are thinking along the lines of living tissue.

It is ** that ** concept that your words inspired ... a biosuit made of "living" material able to perform the multiple functions that skin would perform if it were evolved to handle the Mars environment.

After all, the skin we humans "wear" evolved to serve admirably in an astonishing range of environments.

A designed "skin" has been long imagined by science fiction writers, but I gather from the collection of citations Google found, that work is proceeding at a decent pace, on tissue assembly for human medical purposes.

It would not be a great leap of imagination for a science fiction writer to visualize evolution of the existing human tissue assembly process, to design and assembly of an artificial tissue able to function as a single "intelligent" entity to protect a human inside.

So, my answer to LiveForever is both No and Yes.  No to "3D" printed, and Yes to "nanoprinted" material.

Edit#1: I invite others who have read science fiction along these lines to post references.  I have flickering tendrils of memory of science fiction stories that include ideas along these lines, but I can't tie them to anything at the moment.

(th)

Last edited by tahanson43206 (2020-06-30 08:02:49)

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#11 2020-06-30 08:05:03

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 858

Re: MIT Mars Bio Suit

According to this, the world's highest permanently inhabited settlement is some 16,728' above sea level.
https://www.worldatlas.com/articles/the … world.html

At that altitude, atmospheric pressure is 8psi and partial pressure of oxygen is 1.68psi.
https://www.engineeringtoolbox.com/stan … d_604.html

With this in mind, you could feasibly reduce suit pressure to 2psi of pure O2.

If we could develop a low pressure skin suit that could be donned in a minute or two for EVA, with normal clothing and boots over the top, it would make EVA on the Mars surface dramatically easier.  If it is easy to produce a 3psi suit, how easy would it be to produce a 2psi suit?


Interested in space science, engineering and technology.

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#12 2021-04-29 21:32:09

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,841

Re: MIT Mars Bio Suit

RobertDyck wrote:

When I first joined the Mars Society, I didn't think MCP was real. Then I posted that on the old forum in 1999. A member who is an MP specializing in decompression sickness mailed to me a photocopy of the article from the Journal of Aerospace Medicine, April 1968. It was the paper by Dr Paul Webb, complete with photos of a test subject wearing the first prototype in a vacuum chamber. Wow! I've been a fan ever since.

I've also argued to keep suit pressure low, to not push the limits of an MCP suit. Current EMU, the white suit worn on ISS, uses 4.3 psi. Since ISS uses 1 atmosphere, suit pressure is relatively high to reduce oxygen prebreathe time. But that pressure causes major problems for MCP. Liquid silicone filled pads are required on palm and back of hands to spread the force evenly. Donning (putting on) becomes a problem. MCP works best when pressure is even, but donning and doffing (taking off) means there is a time when the suit is part way on, and you're in the pressure of a habitat (or Earth lab). When suit pressure is high and it's part-way on, it's very uncomfortable. Dr Webb's first prototype used 170 mm mercury (3.3 psi) because that's what NASA was talking about at that time. NASA was going to use 3.0 psi pure oxygen in the Apollo capsule, 3.3 psi in spacesuits. That way a suit could suffer 10% pressure leak without negative consequences. They changed to 5.0 psi pure oxygen in the Apollo capsule, 3.7 psi in suits. I've argued for 2.7 psi O2 partial pressure in habitats, 3.0 psi pure oxygen in suits. Again, 10% safety margin. Habitats with a mix of gas so total pressure is higher. Boulder Colorado has 2.54 psi O2 partial pressure, so I don't think this is extreme. Earth sea level has 3.078 psi O2 partial pressure.

Dr Dava Newman of MIT has said designing an MCP suit for 20 kPa (2.9 psi) is easy, designing for 30 kPa (4.35 psi) is hard. 3.0 psi = 20.684 kPa, so let's use that. Easy is good. Elon Musk is advancing technology quickly. One reason is he applies the principle: if it's difficult, find a better way. If there's an easy way or a difficult way, use the easy way.

One feature of MCP is no cooling system. All you need is a 1 litre water bottle. Use a plastic water bottle designed the same as a plastic pop bottle. Do we need to use more exotic polymer to make it more UV durable, gas impermeable, and able to withstand cold of Mars? Fine, make it of PCTFE: Clarus from Honeywell. But just a plastic pop bottle. With a plastic bag liner like the liner of a Playtex Nurser baby bottle. The liner would be connected to a tube to the helmet. A second tube would connect the water bottle itself to the air of the helmet. As you drink, water volume decreases, which draws air from your helmet into the water bottle. Volume remains constant, so no problems. A safety valve would only allow air to flow from the helmet into the tube if pressure difference is not too great. So if the hose got torn, it wouldn't release oxygen.

Yes, that's the entire cooling system. Elastic leotard. When you get hot, you sweat. Your body regulates temperature. The MCP layer will machine washable. And it will have to be: after wearing it for extended time, sweating the whole time. It will smell like a high school gym outfit. What does your outfit smell like after a game?

An MCP suit includes boots with a rubber air dam at the ankle, helmet with air dam at the neck, air bladder vest with non-elastic outer vest. And an outer layer for thermal and scuff protection. I visualize telemark ski boots, because they're hard with a hinge at the ankle. Makes pressurizing boots easy. Helmet like a closed-face motorcycle helmet. Or Mercury or Gemini helmet. But designed as a safety helmet, so possibly more like motorcycle. With a closed cell foam inside the hard shell, polymer film pressure bladder inside that, then open cell foam for comfort. So two pressure layers for safety. Bladder sealed to frame of visor. With two visors: inside and outer, both sealed to frame. All in case of crash while riding a 4-wheel ATV. The helmet would be tied by cables to the vest, similar to the orange ACES suit used on Shuttle. Thermal and scuff layer would be ski pants and parka, with thinsulate for insulation in atmosphere of Mars, and same outer layer as Alpine mountain climbing parka. With outer gloves made the same way.

Yea, Ok. The elestic MCP layer does require liquid silicone filled pads (bags) covering the groin, around up the butt crack, and trough of the lumbo-dorsal spine.

I've also suggested fit individuals war a thin vacuform plastic shell over the air bladder vest. If the outer vest is just non-elastic fabric, air pressure will expand to a cylinder. The purpose of the plastic shell is to squeeze the vest close to the body. The shell would have 2 parts: front and back, held together with buckles. The shell could use fluting to increase strength and keep it light. Fluting must be curved so it doesn't dig into the air bladder. That can be aesthetic. Muscle plate for men, ample busom for women. wink

PLSS backpack need only oxygen bottle, regenerable CO2 sorbent. One-way valves could ensure breathing moves air through the sorbent, and pressure regulator releases oxygen. A microcontroller could monitor the suit with sensors, using Bluetooth to communicate with an app on your smartphone. Pocket on suit forearm to hold a smartphone, and stylus for touch screen integrated with a glove finger. Bluetooth headset, but with power cable integrated to PLSS? How much power would the PLSS really need? Battery the size of a smartphone battery? Integrated with the helmet so body heat keeps the electronics warm? Most difficult party may be designing a smartphone to survive outside on Mars, and a spacesuit parka forearm pocket to use body heat to keep the smart phone warm.

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#13 2021-04-30 03:18:24

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 858

Re: MIT Mars Bio Suit

This topic is, to me at least, one of the most interesting on the board, because it would seem to allow humans to adapt quite easily to most off world environments.  For all the talk of adapting planetary environments to human needs, it is much easier to work the other way around.

Human tissue presumably has some capacity to expand into any small gaps.  But for genital and groin area, any drop in pressure relative the inside of the body will result in the astronaut messing himself.  Given the contours, an air dam would seem to be the only realistic option.  Having pads up the ass crack doesn't sound very comfortable or hygienic.

My question is, would it be possible to build a suit with slightly different pressure in different areas?  Could we, for example, have 2.5psi feed pressure to the helmet, with an extra layer of elastic covering the astronauts chest, and 2.2psi in the air dams and equivalent pressure in surrounding fabric?  How well would that work?  What is the minimum realistic pure O2 breathing pressure that humans could acclimatise to?  Could we get away with 2.5psi, for example?  Would that make the suit even easier to construct?

Last edited by Calliban (2021-04-30 03:20:08)


Interested in space science, engineering and technology.

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#14 2021-04-30 05:55:03

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For Calliban re #13

Your questions about pressure have been answered by RobertDyck in numerous posts.  RobertDyck has studied the subject in connection with his Large Ship project.  Because of the nature of the forum software, we do not have a way for you to quickly and easily find the citations I am remembering.

As I recall, the posts by RobertDyck reported on work by the US Air Force and by NASA over many years.

If this forum had a ** real ** Wiki structure built in, we could accumulate repeating information like that in a single location which would be easy to find.

I am hoping the project by Oldfart1939 will lead to support for the investment (mostly of time by Mars Society staff) to set up a Wiki for the forum.

Please keep an eye on the 17 member landing party topic, and pitch in where you can.

(th)

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#15 2021-04-30 10:35:16

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

Calliban wrote:

Having pads up the ass crack doesn't sound very comfortable or hygienic.

Pressure must be applied evenly. Elastic fabric does not conform to concave areas. You don't want an elastic band on your... um... testicles. Women have equally sensitive genitals. Remember the elastic fabric is stronger than the strongest girdle. This pad is a plastic bag filled with the same liquid silicone that used to be used for women's breast implants. The liquid spreads the force evenly around the complex shapes of genitals, as well as concave portions of the body. Yes, that's the butt crack, and trough of the spine. The vest will fill the trough of the back, so the plastic bag filled with liquid silicone only need cover the spine trough of the small of the back to where it meets the vest.

Calliban wrote:

My question is, would it be possible to build a suit with slightly different pressure in different areas?  Could we, for example, have 2.5psi feed pressure to the helmet, with an extra layer of elastic covering the astronauts chest, and 2.2psi in the air dams and equivalent pressure in surrounding fabric?  How well would that work?  What is the minimum realistic pure O2 breathing pressure that humans could acclimatise to?  Could we get away with 2.5psi, for example?  Would that make the suit even easier to construct?

You need to keep pressure up to breathe. Air Force experiments found a fighter pilot in his prime, fit and strong from military exercise, can breathe 2.5 psi pure oxygen and continue to operate complex machinery. Of course their definition of "complex machinery" is the cockpit / flight controls of a fighter jet. At 2.0 psi, the pilot can remain conscious for up to 30 minutes, but eventually everyone will lose consciousness. At 3.0 psi pure oxygen, anyone / everyone can breathe that. Partial pressure of oxygen on Earth at sea level is 3.0782 psi, at Boulder Colorado it's 2.54 psi O2 partial pressure. However, human tolerance to low oxygen is not as good in low total pressure. NASA was planning 3.0 psi pure oxygen in the Apollo capsule, before the Apollo 1 accident. Ironically they ended up using 5.0 psi pure oxygen.

As for different pressure in different parts of the suit, humans can tolerate some difference, but not much. Blood tends to pool in low pressure areas.

I said Dr Paul Webb did the initial work on MCP. His first prototype suit was made and worn by a test subject in a vacuum chamber equivalent to 50,000 feet, not hard vacuum. That was done in 1967, paper submitted for publication in December 1967, published in the April 1968 issue of Aerospace Medicine. I said a Mars Society member sent me a photocopy of that paper. I type it into a Word document, and scanned images, embedded them in the Word document. Tried to format it as the original. That paper is talks about pressure gradients, what is actually safe. That paper is here: The Space Activity Suit: An Elastic Leotard for Extravehicular Activity

Dr Webb and a partner got a contract from NASA. He built a second generation prototype suit. That second one added the air bladder vest. The first suit did not have the vest, test subject reported the strong elastic fabric across his chest and upper abdomen made breathing difficult. The second one had greatly reduced strength over the chest / upper abdomen, and the air bladder vest went over that. The vest was connected via hose to the helmet, so breathing air and the air bladder have exactly the same pressure. That eliminated restriction to breathing. If you're familiar with a rebreather used by US Navy divers, a rebreather requires a "counter lung". The diver exhales into the counter lung, then inhales that air back. Lithium hydroxide scrubs CO2 out of that air, and activated charcoal removes smells from bad breath. This ensures no oxygen is wasted, and the pressure tank need only carry pure oxygen. The air bladder vest of the second generation MCP suit acts as the counter lung.

NASA contractor report from James F. Annis and Paul Webb, November 1971, NASA CR-1892: Development of a Space Activity Suit

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#16 2021-04-30 12:37:08

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For RobertDyck re #15

This reply to Calliban is a very nice snapshot of the many posts you have made on this subject.

If we can (somehow) persuade Mars Society management to let us try the Wiki concept for posts such as yours, please think about how you would store/index the post so that it could be easily found when the next new member asks this same question.

Hopefully we will be bringing in more new younger members like Captain J Torriani and Noah, and it is understandable that they would not have had an opportunity to think about the requirements for atmosphere in habitats, in space vessels and in EVA suits.

In the absence of such a framework, is there a set of tags that might help a new member to find the post quickly and easily?

(th)

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#17 2021-04-30 12:59:18

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

tahanson43206 wrote:

If we can (somehow) persuade Mars Society management to let us try the Wiki concept for posts such as yours, please think about how you would store/index the post so that it could be easily found when the next new member asks this same question.)

Who is the head administrator for New Mars? It wasn't set up by James Burk, he was the webmaster of the Mars Society main website. I thought Josh Cryer was. I may have changed after the Great Crash. I remember a wiki on New Mars before the Great Crash. Whoever runs New Mars now will have to be convinced.

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#18 2021-04-30 13:58:19

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For RobertDyck re #17

Thanks for picking up on the possibility we (NewMars forum) might be able to win/earn/deserve a Wiki for members to collect and organize knowledge.

It is likely (from your question) that you have not been following SpaceNut's efforts to persuade management of the value of a Wiki for this group.

There was a Wiki attempted previously, and it has apparently fallen by the wayside.

That suggests to me that the physical structure of a Wiki is something Mars Society management knows how to do.

It is up to the Administrators, Moderators and Members of the forum to demonstrate that an investment of limited time by Mars Society staff would be rewarded with measurable performance by NewMars posters.

I'll ask again ... if you ** had ** a Wiki structure available, how might you store the information you repeated for Calliban, so I could quickly and easily be found by future members who inevitably will ask the same question.

(th)

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#19 2021-04-30 14:30:24

RobertDyck
Moderator
From: Winnipeg, Canada
Registered: 2002-08-20
Posts: 6,484
Website

Re: MIT Mars Bio Suit

Sure, I'll use it.

By the way, Dr Robert Zubrin has a Ph.D. in nuclear engineering, and an Master degree in aerospace engineering. He isn't a computer guy, don't expect him to know how to set up a wiki. James Burk is the Society's computer guy.

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#20 2021-04-30 16:59:02

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,841

Re: MIT Mars Bio Suit

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#21 2021-05-01 06:06:47

Calliban
Member
From: Northern England, UK
Registered: 2019-08-18
Posts: 858

Re: MIT Mars Bio Suit

Thanks Robert.  I will read the documents you provided.


Interested in space science, engineering and technology.

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#22 2021-05-01 08:11:56

tahanson43206
Moderator
Registered: 2018-04-27
Posts: 5,751

Re: MIT Mars Bio Suit

For Calliban re this topic...

It is ** good ** to see your interest in this topic!  Best wishes for success in advancing understanding of the state-of-the-art, and art-of-the-possible.

My interest is primarily in trying to help to make whatever you publish in this (somewhat lean) data structure to be easy for others to find.

The FAQ feature is common in web sites.  There may even be one here.

For SpaceNut ... does this web site have an FAQ capability?

What I'm imagining is that if Calliban (or any other Member) pursues a question and publishes an answer, it might be posted as an FAQ, with a link back to the post where Calliban published it in the first place.

RobertDyck and GW Johnson (and I suspect many other forum ancestors) have created text that is worth remembering (a) and (b) NOT repeating in an endless cycle that wastes valuable time of those who contribute to advancement of knowledge and understanding.  Those are intertwined but separate.

(th)

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#23 2021-05-01 11:54:53

SpaceNut
Administrator
From: New Hampshire
Registered: 2004-07-22
Posts: 21,841

Re: MIT Mars Bio Suit

reposting to topic

GW Johnson wrote:

Re posts 40-42 just above:

I have addressed the MCP suit thing,  and appropriate habitat atmospheres,  in prior years,  both on these forums,  and on my "exrocketman" site.  There is a fair-to-middlin'-good Wikipedia article on the MCP suit,  that even gives some history that happened prior to Dr. Paul Webb experimenting with his elastic space leotard design in the late 1960's.  My Dad (who was an aeronautical design engineer,  as was myself) knew Webb.  Webb was the go-to survival expert for high altitude bailout,  among other things,  which was of interest to my Dad's design of high performance jet aircraft in the 50's and 60's and 70's. 

The Wikipedia article mistakenly claims that suit pure oxygen feed pressure must be 4.3 psia;  they got that from NASA.  The same article correctly gives the minimum feasible pure oxygen feed pressure as 2.5 psia,  further down in the article!  That's pretty much the same number as I got,  from looking at flight oxygen mask limits,  and allowing for water vapor displacement inside the wet lungs.  You can see what I determined on the "exrocketman" site,  if you use the navigation tool on the left.  Click on 2016,  then click on February,  then the title is "Suits and Atmospheres For Space".

The main problem with Webb's suit was difficulty donning and doffing the tight garment pieces.  His fundamental suit is essentially just vacuum-protective underwear,  with an oxygen pack,  a breathing helmet,  and a tidal volume bag.  You put unpressurized protective outerwear garments on,  over his vacuum-protective underwear. That's how you cope with mechanical and thermal threats.  I came up with a way to reduce the don/doff difficulty by reducing the number of layers,  and adding back in the capstan tensioners concept of the "partial pressure suit".  That is also posted on "exrocketman":  click on 2017,  then November,  and the title is "A Better Version of the MCP Space Suit?"

The first physiology limit here is partial pressure of oxygen available inside the wet lungs where water vapor displaces it,  along with the atmospheric pressures at altitudes where vented pure oxygen masks become necessary in flight.  Whenever the ambient atmospheric pressure is too low,  you have to do "pressure breathing" to get enough oxygen diffused across the lung tissues into the blood.  That diffusion pressure difference (oxygen partial pressure inside the lungs vs oxygen partial pressure in the blood) sets the min oxygen partial pressure you have to have in your breathing gas pressure,  once you allow for the displacing effect of water vapor partial pressure at body temperature.    

What I got,  and posted in the suits and atmospheres article,  was 2.48 psia min pure oxygen feed pressure (in the helmet),  remarkably close to the 2.5 psia Wikipedia cited in their article.  I recommended a minimum suit pure oxygen pressure of 2.67 psia,  which gives you some leakdown margin (near 10%).  Back in 1968,  Webb was using 3.3 psia,  because that was what NASA was then using.  They've since gone to 4.3 psia.  Dava Newman,  who did MCP work at MIT,  said during her efforts,  that MCP design at 4.3 psia was hard,  but it was easy,  at or below 3 psia. 

I could not get down to zero pre-breathe time with my suit recommendations,  but I did come up with a somewhat-lower-pressure,  slightly-higher-oxygen habitat atmosphere that also met very realistic fire danger criteria based on chemical reaction-rate effects.  Pre-breathe times should be much shorter than those NASA has to use going from "air" at 1 atm to pure oxygen at 4.3 psia.  I would have examined that issue,  if I knew how to estimate pre-breathe times;  I don't.

The second physiology limit here is that bad things happen if the pressure in the fluids and tissues of your body do not match the pressure of the gases in your lungs.  If that difference exceeds 2 psi,  the lung tissues rip ("pneumothorax"),  and you drown in your own blood.  This is irreversible damage,  but death takes a few to several minutes.  Scuba divers (and the hard hat divers of old) knew about this,  and were trained to avoid it:  never hold your breath as you rise. 

At lower differences,  the lungs are OK,  but over time,  blood fluids perfuse into the less-pressurized tissues,  causing very painful,  but reversible swelling ("edema"),  and fainting as blood pools in unpressurized extremities.  It takes about half an hour for unpressurized hands to start swelling from vacuum exposure.  What prevents all this is applying a pressure to the skin all over the body that equals the pressure of the gases in the lungs.  It doesn't have to be perfectly even,  but it does need to be fairly close to even. 

Because our bodies are essentially water balloons in their physical characteristics,  it does not matter one whit whether this countering pressure applied to the skin ("counterpressure") is applied as gas pressure,  or as mechanical pressure.  Doesn't matter how you squeeze the water balloon,  the pressure inside it is still the same. 

The old "partial pressure" suits were tight garments that countered the required breathing pressure for very high altitude bailouts (70,000 feet and higher).  Hands and feet were left unpressurized,  and limbs not as squeezed as torso.  It worked fine for a 10-minute bailout.  The original "full pressure" suits (gas balloon suits) were a response to much longer exposures than a bailout (for the U-2 and SR-71 high altitude spy planes).

My point:  there is sufficient payoff here with MCP (lightweight,  launderable,  very supple space suits of great mobility,  and great versatility) so that somebody really needs to be working on this!  As far as I can tell,  no one is.  Dava Newman was hired away from MIT by NASA,  but not to work on space suits,  MCP or otherwise.  Paul Webb is dead.

My "exrocketman" site is "An Ex Rocket Man's Take On It",  located at http://exrocketman.blogspot.com

GW

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