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#1 2013-12-01 07:31:53

Tom Kalbfus
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Powered Spacesuits

I noticed there was much talk about humans adapting to a partially pressured environment to limit the prebreathe time to maximize the time available to work outside on the surface. I just thought I might mention an alternate solution. What if a fully pressurized the Mars suit, one pressurized to one standard Earth atmosphere at Sea Level is augmented with a powered exoskeleton?

I believe the Army is working on exoskeletons to take the load off our soldiers and to allow them to carry heavy weights, what if we were to outfit a fully pressurized Mars spacesuit with an exoskeleton, to allow the astronauts to bed their arms, legs and fingers with ease?. What if the astronauts strength was augmented, by a robotic exoskeleton to allow him to make tremendous leaps on the surface of Mars such that he doesn't even feel the weight of the Mars suit or his life support pack? If he could carry a larger life support pack, he could stay out on the surface of Mars for a longer period, he could pick up larger rocks that even under Martian gravity a human couldn't carry. What do you think of this idea?

Last edited by Tom Kalbfus (2013-12-01 07:37:38)

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#2 2013-12-01 09:24:00

RobertDyck
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Re: Powered Spacesuits

Unnecessarily complicated. Humans can breathe just fine at lower pressures. As I said in those other discussions, Boulder Colorado has 2.54 psi partial pressure oxygen, so there's no need to provide 3.0 psi. Apollo used 5.0 psi total pressure, with 60% oxygen and 40% nitrogen. A simple solution is to use the same on Mars. But 5.0 * 60% = 3.0 psi O2, and again humans don't require that.

The EMU used on the space station already has too much pressure. The reason was to pressurize ISS to fully 1 atmosphere, equal to KSC. It's not even Boulder's pressure, it's sea level. That high pressure in the station is the reason they increased pressure in suits. To limit the differential, and hence to reduce prebreathe time. For Mars, the solution is to choose a habitat pressure that permits decompression into a suit without any prebreathe time at all. Not some section of the habitat; all of it.

Some people have commented on psychological factors. One is to let astronauts on Mars just go outside. Not those scheduled for an EVA for duty, but just as entertainment. Whether they throw around a football, or more likely just explore Mars or conduct some personal research. Mars surface has to be treated as "outside", rather than some hostile environment.

I live in Canada. Here winter is very cold. Going outside requires winter clothing: parka, boots, gloves or mitts. This is minimum, I also wear long underwear, and know one late-middle-age woman who wears ski pants. A working furnace in your house is life support; without it you'll die. Wearing correct clothing to go outside is necessary, without it you'll only last so long before you die.

When I was in my 20's and got my first full-time permanent job, only the managers had an office with a window. Everyone else had a cubical. In winter we would arrive before the sun rose, and the sun would set before time to go home. I could only see the sun on weekends. It gets to you. Winnipeg is in the south of my province, northern towns consider this to be the warm, luxurious, southern location. But Winnipeg is 60 miles north of the border with North Dakota, and yes I said north of North Dakota. For a week in June around the solstice, the sun doesn't set until 10:00pm daylight time. But in winter it can get to you. One co-worker took me for walks over lunch to avoid Seasonal Affective Disorder; I appreciated that, it helped. And Devon Island is almost perfectly north, about 2,840km away (measured by Encarta atlas). Going for walks on Mars will be very necessary.

I still argue for Mechanical Counter Pressure. There are several reasons. One is to keep it simple: the fewer things that can go wrong, the fewer things will. Another is for cleaning: an MCP suit is machine washable. Another is safety: if your suit gets a tear while outside, you get a bruise. If a gas bag suit gets a tear, you die. And repair: a tear can be repaired by sewing. A soft gas bag suit is far more difficult. A hard suit just can't be repaired. And the higher pressure you operate at, the greater the likelihood of a leak.

Last edited by RobertDyck (2013-12-04 15:33:38)

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#3 2013-12-01 09:53:44

SpaceNut
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Re: Powered Spacesuits

exoskeleton are something we have talked about lots of times here
Mechanical Counter Pressure suit You're a 1st Marsian Settler   Radio ID'd Teabags - ...technohelp for elderly  Mars Colonists visit the ancestral homeworld Building soil

Everything from talking about it as a support strengthening system to giving enclosure to its occupant from the elements of space.

5-raytheon-xos2.jpg

The army has been working on The 2nd Gen Exoskeleton Robotic Suit .Posted Oct 13, 2010 by Video Blogger

Raytheon's second-generation exoskeleton (XOS 2), essentially a wearable robotics suit, was unveiled for the first time recently during an event at the company's Salt Lake City research facility. XOS 2 is lighter, stronger and faster than its predecessor, yet it uses 50 percent less power, and its new design makes it more resistant to the environment.

Military exoskeletons uncovered: Ironman suits a concrete possibility


http://www.army-technology.com/features … ity-5.html

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#4 2013-12-01 10:45:11

GW Johnson
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Re: Powered Spacesuits

I think the exoskeleton idea would be great for stuff like loading dock and heavy construction work.  In that sense,  the sci-fi movies got it right. 

I think we really do need an MCP suit,  but I think the concept should be revised to "vacuum-protective underwear" with a pure O2 breathing helmet and tidal volume bag,  rather than the traditional "everything for any use" idea.  You wear whatever outer clothing is appropriate to the job you are doing,  over your "vacuum-protective underwear" MCP suit.  Every job is different,  just like here at home.  In fact,  the outer clothing can be exactly what we wear here at home,  boots and all. 

I have some body-compression/breathing-pressure requirements for MCP designs analyzed and posted (that include the water vapor displacement effect) over at http://exrocketman.blogspot.com,  in an article dated 1-21-2011,  and titled "Fundamental Design Criteria for Alternative Space Suit Approaches".  These compression recommendations are surprisingly low to some (but not me),  they ignore the nitrogen-blowoff decompression often required from higher-pressure habitation atmospheres,  but they do fall within the reach of MCP compression garments made with materials available since 1969. 

I based this analysis on effective wet-lung partial pressure of O2 equivalent to that at 10,000 feet altitudes here at home.  Even-lower values would work,  but not very effectively for unacclimatized flatlanders.   There has to be a habitation atmosphere compatible with no-decompression MCP suit use at these lower compression levels,  and with health safety for inhabitants that are reproducing successfully.  I just don't know what it is.  Yet. 

There's not much time left to prove out these ideas,  if the first trip will really take place circa 2030.  The smart thing to do is establish a base on that first trip.  The commercial guys will follow quickly,  once that is done. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#5 2013-12-01 22:34:50

JoshNH4H
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Re: Powered Spacesuits

To anyone proposing these exosuits: What benefits do these have compared to operating an equivalent machine from a control booth with live audio-video feed, either inside or outside the hab?

I love the idea of Mechanical Counter Pressure vacuum underwear with coats and heating elements over it.  Does anyone have any idea how difficult it would be to put on this MCP underwear?


-Josh

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#6 2013-12-04 12:49:45

GW Johnson
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Re: Powered Spacesuits

Exoskeleton suits:  there are lots of jobs better done by remote teleoperated equipment.  There are some jobs where eyes on site with full field of view works better -- and that's where an exoskeleton suit comes in handy when the forces exceed what a human can do.  Hard to name specifics,  but you have to be prepared for both eventualities,  since unplanned things have such a nasty habit of happening. 

Vacuum-protective underwear (MCP done "right"):  this frees up people physically to do a lot more,  both in terms of agility,  and in terms of fine motor skills.  For one thing,  you can doff the compression gloves and work barehanded for many minutes,  as long as thermal injury is not an issue.  Human applied force levels can be higher,  when unimpeded by a resistive gas balloon suit.  Done with stretch fabrics,  it would be difficult to don,  as it was in the late 1960's,  but you can leave it on whether inside or outside.  All you have to remove going inside is the helmet,  oxygen backpack,  and your outerwear.  You sweat right through it for cooling.  I am assuming we can do a better job now of garment design than the 1969 model. 

GW


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#7 2013-12-04 16:08:20

RobertDyck
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Re: Powered Spacesuits

I have talked to one person who was test subject for an MCP glove. He said it hurt, until he put his hand in the vacuum glove box. Mechanical Counter Pressure is an extremely tight girdle. So tight that it restricts blood flow unless you have the same pressure all over your body. So no, you can't just take off outwear, helmet and back pack. Donning and doffing is an issue because it's so tight.

One year the Spacesuit Taskforce organized a symposium as one track at a Mars Society convention; they invited Dr. Paul Webb. Actually, I had suggested they invite Dr. Webb because that year was his 80th birthday; I was worried he would soon suffer effects of age. But they didn't just invite him, they invited major researchers from Hamilton Sundstrand and ILC Dover. They hoped for knowledge, but the young contractors were more interested in pitching their stuff. Anyway, he had original video of his original 1960s test. That paper was written in December 1966, although it was published in 1967.

His 1960s design used multiple layers, adding up to the required pressure. His 1972 paper used stronger elastic fabric, fewer layers. He added a vest bladder which acted as a counter lung (rebreather technology) as well eliminating difficulty breathing. He used a single layer of relatively weak elastic fabric over the chest under the vest. While his 1960s version worked in a chamber equivalent to 50,000 feet, the 1972 version worked in hard vacuum.

A suit you can wear without helmet, gloves or backpack? That would require a suit that can decompress. There have been some proposals. One idea is a strip of fabric make contractile polymer or shape memory alloy, which would relax to decompress arms, legs, and hips while the helmet and gloves are off. The strips would contract to provide pressure once they're on. I have raised concern about safety: I want to ensure power loss does not result in loss of pressure. So such a system would require power to relax, while removing power would contract. How do you do that?

Dr. Webb's 1972 design used pressurized boots with neoprene gasket at the ankles. This would allow something to provide air pressure when the suit pressurizes. Either a hose to the vest, or a solenoid with a cylinder like a bicycle pump.

Dr. Webb laid a thin bag filled with liquid silicone in the trough along the spine, to distribute force from the elastic. He found nothing but fabric was requires for underarms. Another bag in the crack of the but. And a bag over/around the genitals (male or female).

All this means the adjustable strip need only be along each arm from the collar to wrist, and each side from the ribs to ankle. Now the big question: how do you make a strip of fabric get wider when power is applied, then contract when power is removed? And ensure that fabric can move as the person walks and moves about?

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#8 2013-12-05 01:50:31

JoshNH4H
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Re: Powered Spacesuits

With regards to something that tightens when energy is applied, it's not too tough to imagine a suit with laces, like on a shoe, where instead of being tied in a knot (Not that this is necessarily impossible-- Worth investigating?  It would require a lot of string and the right knot but isn't necessarily impossible by any means) there could be a little electrical component to stretch an elastic part where needed.

Having said that, this is silly-- just use string.  Don't reinvent the wheel when the double knot I learned when I was five will suffice!


-Josh

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#9 2013-12-05 10:26:55

RobertDyck
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Re: Powered Spacesuits

When I was part of a medieval recreation society, I had a fancy costume made. The seamstress made the jacket a little too small. The jacket was a doublet, with laces in front. I couldn't get the laces even. It would always bulge in one place, but completely close in another. I expect the same if you try to use laces on an MCP suit.

Interesting. Looking at old suits. MCP was used by the air force for partial pressure suits, for high altitude pilots. They developed a capstain system. That means something along the same locations I listed, but this something would twist automatically to tighten and provide pressure. Later versions provided a vest, like Dr Webb's. So Dr. Webb's work is very much based on earlier work. This one doesn't have the vest, but does have a picture.
s2suit.jpg

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#10 2013-12-05 10:40:27

GW Johnson
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Re: Powered Spacesuits

Lace-up is slow but very effective.  That's what they used in the earliest pressure-breathing rigs (1940's) and partial-pressure suits of late 40's and early 50's (a real misnomer if ever there was one). 

In the more-developed partial-pressure suits of the mid-50's,  they went to an inflatable tube that tensioned and relaxed the non-elastic fabric.  The compression they achieved was very uneven,  and hands and feet were unprotected.  But it was good enough for a 10 minute fall bailing out from 70-80,000 feet.  Medically,  80,000 feet is hard vacuum. 

I would suggest combining that inflatable idea (but reversed) with elastic fabric.  Build it so that it requires inflation pressure to relax the elastic grip by increasing girth,  not decreasing it.  That way it is fail-safe when out in vacuum.  Relaxed grip should make donning and doffing much easier than the panty-hose problem of the late 60's. 

There is absolutely nothing wrong with the gel bag way of coping with otherwise-intractable anatomical geometries.  That's how you "tailor" the suit to fit its wearer,  more so than the suit itself.  Fit is essential to achieving even compression,  that's the downside with MCP.  There's genitalia,  breasts,  and small-of-the-back problems to address with gel bags. 

BTW,  if the suit tears,  you don't have to suffer much bruising at the tear location.  Just give the torn spot a tight wrap of "Mach 1" tape.  Any compression beats no compression at all. 

You know what they say about duct tape and bailing wire.  That's the band-aid kit you use until you get back to the shop. 

GW

Last edited by GW Johnson (2013-12-05 10:41:28)


GW Johnson
McGregor,  Texas

"There is nothing as expensive as a dead crew,  especially one dead from a bad management decision"

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#11 2013-12-05 15:52:43

JoshNH4H
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Re: Powered Spacesuits

RobertDyck- It seems possible that that was an artifact in part of engineering, and in part of the relatively small compression pressure.  For a properly designed suit at 30-40 kPa I would expect the body to be squeezed up against the suit so that the pressure ended up being equal everywhere.

With regards to laces, we would of course want something a bit better than a shoelace.  The big problem with laces as they're currently used in clothes is friction.  This will reduce the tension in the lace as you get farther from the point at which it's pulled.  This could be alleviated by running the lace through a series of small pulley wheels, so that the pull is more even.  I don't know about lubrication, since even Graphite doesn't work well in a vacuum, but I would think that something simple like polished metal on plastic for the bearing would have a low enough coefficient of friction to be workable.  I would think that ball bearings are too complicated (Keep It Simple, Stupid!), but I'm no expert.

Laces would also give the suit some degree of size tolerance.  By spacing the pulleys at different intervals, so that there are more per unit length when the body radius is larger, it will be possible to keep the pressure relatively even. 

My question is what level of pressure variance is acceptable?  If your suit pressure is 30 kPa, and you can keep the range of pressure variations down to 10% (e.g. +5%) of that, your pressure variation is 3 kPa.  Does anyone know just how tight corsets got?  3 kPa over a reasonably sized torso is a total force of 762 N (170 lb).  Given the rather extreme modifications to body shape that they did with corsets, I rather believe that this could have been the case.

Of course, we wouldn't allow such a large deviation over such a large area.  We have a relatively good idea of the shape of the human body, and with modern 3D imaging techniques it is far from impossible to design a program to output the optimal pulley spacing given ten or twenty minutes spent in a body imaging chamber.

Given proper spacing of pulleys, the tension in the laces can be arbitrarily low, but a reasonable value is whatever you can get wit ha good hard pull from a human arm.  Perhaps 300-400 N (75-100 lb)?  The suit could be designed with 2 sets of laces, one from the left ankle up the left leg, up past the rib cage, up to the armpit and then down the side of the left arm to the wrist with the pull cord at the wrist, and the same on the right side.  From there the helmet could contain straps that would pressurize the shoulders, and there would be gloves, boots, and of course air for the head and neck.


-Josh

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#12 2013-12-05 17:49:43

RobertDyck
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Re: Powered Spacesuits

I was thinking of recalculating hab pressure. The worst case scenario is a spacesuit leaks as soon as the astronaut steps outside. Since Apollo suits were designed for 10% pressure leak resulting in the same partial pressure O2 as the spacecraft/Skylab, I used that. So the design limit is 10% suit pressure loss. I use 3.0psi pure O2 for the suit, and 2.7 psi partial pressure for the habitat. So using 2.7 psi total suit pressure after a leak, and assuming it gets there immediately after leaving the airlock, that changes habitat N2. Now 2.7 * 1.2 = 3.24 psi partial pressure N2. Mars atmosphere measurements by Curiosity show more argon than Viking 2, so we don't have to stick with the 2.7:1.6 ratio of N2:Ar. We could use a 1:1 ratio of N2:Ar; the human body can withstand more Ar than N2, but why push it? So that gives 2.7 psi O2 + 3.24 psi N2 + 3.24 psi Ar = 9.18 psi total pressure. That is  0.624661 atmospheres. That's significant pressure! Argon causes voice pitch to drop; just as helium makes you sound like a munchkin, argon makes even a woman sound like a deep voice man. Too much?

Getting back to suits: this still requires 3.0 psi elastic pressure from an MCP suit. But Dr. Webb's work showed strong elastic over the chest and upper abdomen is not good. It restricts breathing. So he used an air bladder vest, and elastic fabric under the vest with only a fraction the force. That means we only need a closure that reaches just under the vest, so just to the waist. Not the hips, to a woman's waist, just above the pelvis.

So the S-2 suit used a pressure tube along the sides? The very short description called it "a modified capstan partial pressure suit". A nautical capstan can pull two ropes from different directions at once. Just wrap the ropes (or laces) together, one lace wrapped a half turn farther.
capstan.gif

Rather than a complicated vacuum pulley system, could multiple capstans pull the spandex tight? Shape memory alloy spring? Motor? Solenoid? Contractile polymer? Or just pneumatic? Some sort of a latch, hook, or zipper to hold it tight?

Last edited by RobertDyck (2013-12-05 21:39:35)

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#13 2013-12-05 20:53:14

JoshNH4H
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Re: Powered Spacesuits

It's interesting how different the Curiosity and Viking results are.  According to Curiosity, the Martian atmosphere is:

96% CO2
1.9% Ar
1.9% N2
0.2% Other stuff, primarily Oxygen and Carbon Monoxide.

They note in this paper that:

Mahaffy, et. al. wrote:

The most notable differences between the SAM measurements and previous data are in the relative abundances of Ar and N2 and in the isotopic compositions of Ar and CO2. The Ar/N2 ratio and the N isotopes provide important constraints to models for assessing the relative contributions of internal and atmospheric sources to gas inclusions in shock-produced glassy martian meteorites. The isotope data are important for constraining models of atmospheric evolution. Whereas Viking found nitrogen and argon to be the second and third most abundant atmospheric gases at 2.7 and 1.6% by volume, respectively, SAM determines nearly equal volume mixing ratios for these constituents. Ar is found to be 21% greater, whereas N2 is 30% lower than the Viking values. The resulting Ar/N2 ratio of 1.02 measured by SAM is ~1.7 times greater than the value reported from Viking measurement (4). Both Ar and N2 are noncondensable and practically inert gases on Mars, so their relative abundances are not expected to change considerably with time. We suspect that the difference from Viking results is due to different instrumental characteristics rather than some unknown atmospheric process, although seasonal variation in N2 is yet to be tracked. The use on Mars of a turbomolecular pumping system (33), as well as repeated SAM analyses are expected to produce a more accurate determination of the ratio of these gases than the previous Viking in situ measurements whose mass spectrometers employed small ion pumps.

Even assuming we go for a mix that is 17 kPa O2, 15 kPa N2, 15 kPa Ar, 2 kPa CO2, 1 kPa H2O (50% relative humidity) (total 50 kPa).  This is the pressure at an altitude of 1.25 km above sea level, equivalent to the oxygen content at (After going to the wikipedia article for nearly every major city I can think of) Salt Lake City, Utah, atomic weight of breathing gases won't be too different from what it is on Earth.  Here, it's a mean atomic weight of 29.  There, it would be 33.1.

This will make a difference that is perhaps noticeable but probably insignificant.

17 kPa is 2.5 psi, so we're more or less in-line there.  Modern spacesuits use 32 kPa of pressure, of which 21 kPa is Oxygen.  I'm not quite clear on the mechanism by which CO2 is removed-- is the air simply jettisoned and replaced by air with 100% Oxygen?  This seems quite wasteful to me.  It would be nice if there were a way to selectively scrub CO2 from the suit's air.  Regardless, we don't actually breathe all that much oxygen.  Pressurized in its pure form to 20 MPa (compared to 20 MPa in industry for a wide variety of compressed gases and in Scuba diving), and cooled to Martian Ambient of 230 K, the density of Oxygen is as high as 325 kg/m^3.  At this temperature it will still be a gas.  According to Atomic Rockets, the average person needs .8 kg of Oxygen per day.  Assuming you use the flush-out method of Oxygen replenishment and a suit pressure of 18 kPa O2, 2 kPa H2O, and 5 kPa CO2 it will be necessary to have about 5 times as much oxygen as will actually be used.  Assuming that a person will actually need 1.2 kg per day (Strenuous activity, or whatever really), twelve hours of air will have a volume of .009 cubic meters, or 9 liters.  Twelve hours of Oxygen would correspond to two cylindrical tanks, each of which is 15 cm in diameter and 25 cm tall.  Very reasonable.

With regards to elastic suits:

I would be willing to bet money that what inhibited breathing about elastic over the chest was not inherent to MCP but rather inherent to elastic materials, because they require energy to expand and contract.  Given this information, I would suggest a modification of the Lacesuit.  Instead of fixing the lace, it might be possible to allow the lace to move while still exerting a constant force on it at its end.  Admittedly, I'm not sure how this would be done.  Perhaps it would be possible to take advantage of fluid mechanics somehow.  I'll certainly spend some time thinking about it, but if you have reason to believe that it's impossible (I realize that I'm proposing a non-hookean structure) please let me know!

I don't agree that the pulley arrangement I'm suggesting is complicated, per se.  It simply involves the replication of a fairly large number of extremely simple parts.

I don't really understand what you're saying about capstans; What is the suit design you're proposing?


-Josh

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#14 2013-12-05 21:59:32

RobertDyck
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Re: Powered Spacesuits

Suits from Mercury through Shuttle used lithium hydroxide to absorb CO2. It wasn't ejected into space, it was absorbed into a solid. But starting with ISS, the lithium hydroxide has been replaced by silver oxide. That adsorbs CO2. Once the astronaut returns to the station, the silver oxide canister is moved from the PLSS backpack to an oven where the CO2 is baked out. That CO2 should be routed directly to the Sabatier reactor, but unfortunately the contractor who made it (Hamilton Sundstrand) didn't care about efficiency. The baked-out CO2 is released into ISS cabin air. The Russian life support system had to re-absorb the CO2. Now that Node 3 on the American side has life support, it absorbs CO2 which is then baked-out a second time to be routed to the Sabatier.

Yes, suits absorb/adsorb CO2 into a solid, and replace that CO2 with pure oxygen. The PLSS backpack includes tanks of pressurized pure oxygen. It's a rebreather.

Bottom line: suit CO2 is routed to a Sabatier which combines it with H2 to become methane and water. The water is routed to electrolysis, broken into H2 and O2. The O2 is released back into the cabin.

Capstans: don (put on a spacesuit) with suit fabric relatively loose. That makes it easy to don. Wear the suit without pressure while cabin pressure exists. When decompressing in an airlock, or in case of sudden cabin decompression, the capstans pull the elastic fabric tight. That provides suit pressure. The "tightening" strip runs along both arms from the vest above the shoulder to wrist; and along both sides from waist to ankle. Boots are hard, with air pressure. When capstans pull MCP fabric tight, a mechanism pressurizes air in the boots. Using Dr. Webb's boot design, a neoprene air dam at the ankles provides an air seal. Silicone liquid bags along the trough of the spine, and crack of the but, and over/around genitals. We don't need silicone over breasts because the air bladder vest will cover breasts.

Last edited by RobertDyck (2013-12-05 22:03:03)

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#15 2013-12-06 01:26:32

JoshNH4H
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Re: Powered Spacesuits

It sounds like your capstan proposal is the same as my pulley proposal in terms of effect, I'm just suggesting a different layout and design-- where you have capstans, I have little pulleys.  Correct?  Taken to their logical layout, these are not just similar but actually the same.

After a bit of thought, I have in fact designed a spring whose force does not change as its length changes.  See the diagram below:

27ysaw8.jpg

Each of the four springs in this diagram are the same spring, which is to say that they have the same spring constant and the same unstretched length.  However, one spring is stretched by a length e.  Using Hooke's Law, F=-kΔL, we find that:

F=-kΔL+k(ΔL+e)

So that:

F=ke

For all values of ΔL.  From an energy standpoint, the default position of the system is for the left spring to be as compressed as possible and for the right one to be as stretched as possible.  With an energy input (for example, the expansion of chest volume due to inhalation.  Like on Earth, the energy for this will be provided by the increase in volume of pressurized air in the lungs) the tether attached to the spring assemblies can be moved, but this motion will not result in significant variation in the force applied to the tether, maintaining the Lacesuit at the same pressure.

It's a very simple mechanical system that's not failure prone and gets the job done.  That's what we want, after all.

Edit: The mental image I hope I'm giving everyone is Robert Zubrin (Or someone else who you would normally expect to be dignified and worthy of respect) wearing a combination of this and this, with a daft punk helmet on his head.


-Josh

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#16 2013-12-06 02:16:24

RobertDyck
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Re: Powered Spacesuits

I don't have a smart phone, the digital camera is a pain to operate. The camera I bought doesn't work any more; the only "working" one was acquired free through recycling. The miniature joystick to select menu options don't work. So let me use text.

Instead of a lot of laces with a single actuator, rather use a lot of actuators. Use capstans all along the arms, each pulling fabric. Or a limited number of capstans, each pulling short laces. That way you don't have to worry about lacing bunching up, leaving a big gap.

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#17 2013-12-06 02:53:25

JoshNH4H
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Re: Powered Spacesuits

What do you intend to use as an actuator?


-Josh

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#18 2013-12-06 09:24:04

RobertDyck
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Re: Powered Spacesuits

I left it vague on purpose. The point is we don't need yet-to-be-invented contractile fabric.

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#19 2013-12-07 22:19:39

RobertDyck
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Re: Powered Spacesuits

Ok, no answer to my question. I said

Rather than a complicated vacuum pulley system, could multiple capstans pull the spandex tight? Shape memory alloy spring? Motor? Solenoid? Contractile polymer? Or just pneumatic? Some sort of a latch, hook, or zipper to hold it tight?

So what about this: Spandex MCP fabric, with a non-elastic band for lace holes. Then corset laces to pull it tight. Several actuators to pull the laces, each the size of a sewing machine bobbin. Rather than just one actuator for an arm, instead one every 6" or so. That would avoid laces bunching up. So one bobbin would pull tight laces 3" on either side. Ends of each lace sewn to the non-elastic strip. Once tight, the bobbin should latch closed, so no power is required to maintain pressure.
reload-bobbin-thread-sewing-machine-service.jpg
Do we add a zipper? So once laced tight, the zipper is redundant closure to hold the MCP fabric tight.

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#20 2013-12-08 13:24:06

JoshNH4H
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From: Pullman, WA
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Re: Powered Spacesuits

How does this deal with the increase in chest volume due to breathing?


-Josh

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#21 2013-12-08 15:51:33

RobertDyck
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Re: Powered Spacesuits

Air bladder vest, based on Dr. Paul Webb's design for his contractor report to NASA, November 1972. The vest has a constant exterior shape and volume. Interior surface of the vest moves with the chest and upper abdomen (stomach). The air bladder is the counter lung for the rebreather PLSS. That vest extends to the waist (men's waist, hips for women), and has an air hose connecting it to the helmet. To squish the vest from a cylinder to a body fitting shape, you will need a plastic chest plate. Use a type of plastic that can withstand the cold of space, and of Mars. To make the chest plate thin and light-weight, it requires fluting, like late medieval armour. Creases of a car's hood does the same job. Details of what those creases look like are not as important as their presence; might as well make them look good. So give every male spacesuit 6-pack ab's and pec's that look like Arnold Schwarzenegger. Every female like Dolly Parton. The air bladder will make every cup size several sizes larger. Of course the bladder will be covered by a thermal/scuff layer that looks and works like a parka, so you won't normally see it. But no one should worry about an MCP suit showing too much middle-age spread.

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#22 2013-12-08 17:56:19

Tom Kalbfus
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Re: Powered Spacesuits

What's really going to need a powered space suit would be one designed for Venus.

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#23 2013-12-08 18:21:11

RobertDyck
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Re: Powered Spacesuits

Yea, you want this discussion thread redirected back to powered suits. Yes, you will need one for Venus. Phil Nuytten invented the Newtsuit, a hard suit that maintains 1 atmosphere pressure inside while outside pressure gets extreme. He built it to dive up to 1,000 feet of ocean. Then the US navy asked him to redesign it with their fancy materials; he built one to dive 2,000 feet. What we need for Venus is equivalent to 3,000 feet; the same pressure. And Venus has 90% surface gravity, so basically the same weight.

250 pounds, so it will require power assist.
newtsuit-main.jpg

The same inventor came up with Exosuit: 500 to 600 pounds, depending on config, so even greater need for power assist.
exosuit-main1.jpg

::Edit:: Exosuit is the navy version.

The standard Exosuit is rated to 1,000 ft or 445 psi. Its crush depth is over 2,000 ft (890 psi). Nuytco intends to test each suit to 623 psi, equivalent to 1,400 ft. This lets the suit be certified as an A1 Submersible.

http://machinedesign.com/news/exosuit-d … underwater
Note: 890 psi = 61.363 bar, and Venus surface pressure is 92 bar.

The Exosuit is covered in an A356-T6 aluminium alloy skin cast to an average thickness of 0.375 in. Thicker ribs support high-stress areas of the suit. The suit is cast into molds that can also accommodate titanium alloys that withstand greater working depths.
...
The joints are machined from 6061-T aluminium stock and use silicon nitride bearings and PTFE seals. On some models, specially designed seals preserve joint integrity when pressure switches from being greater outside the suit to being greater inside or back the other way.

So it already uses silicon nitride bearings and PTFE (Teflon) seals. Both are immune to acid. Silicon nitride can withstand heat. PTFE can withstand the heat of direct sun in Low Earth Orbit or the Moon, but not Venus. It can withstand heat to +300°C, but Venus surface is +450°C. Kapton is said to retain good strength at +500°C for short time, and zero strength above +800°C. Aluminum alloy cannot withstand that much heat either, but the article already says the moulds work with titanium alloy. So titanium alloy with Kapton seals? ALON visor? Use vapour deposition to apply a titanium nitride coating to the titanium alloy? Titanium nitride is highly corrosion resistant, but also the gold colour you see on Iron Man in the movie. Cue music: "I am Iron Man".

More detail: inside the ALON visor, place a very thin, almost film visor of Kapton. Inside that more visors, each a rigid film. This forms a multi-pane window. Here in Canada we know the benefit of multi-pane windows. It's cold. Weather report says as I write this it's -23.7°C, but wind chill is -33°C. But one night in January 2005, weather reports at the time said the low was -41.0°C; real temperature, not wind chill. Weather statistics now say it only got -39.0°C, but close enough. We need multi-pane windows to keep in the heat. A Venus helmet would need a multi-pane visor to keep out heat.

Last edited by RobertDyck (2013-12-09 00:34:05)

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#24 2013-12-08 21:58:34

Tom Kalbfus
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Re: Powered Spacesuits

I think a Venus suit would also come with an umbilical cord connecting it with the lander, to pump coolant fluid through the suit which draws heat away from the suit and into the lander, the lander would also have radiator fins and a nuclear reactor to keep the lander cool and by extension the powered suit via the umbilical. The astronaut would then collect rocks and soil samples within the umbilical's radius of the lander, he might have a face plate constructed out of clear diamond. The astronaut would collect the rocks, place them in storage containers in the lander. And then he would back into and dock his suit to the lander, climb out of the suit into the cooled lander. The lander would then pump hydrogen into the ballast tank and then rise up into the atmosphere due to buoyancy. Once the temperature dropped sufficiently, a balloon would be inflated, and a propeller would drive the lander to the floating mother ship at an altitude of 50 km, the astronaut would then transfer to the mother ship climb into a small capsule on top of the ascent rocket bringing his rock samples with him. The ascent rocket is then drop launched from the mother ship, rinsing into orbit, where it is met by the interplanetary transfer vehicle to return the astronaut to Earth. The ascent rocket would require two to three stages to reach low Venus orbit. I think that is how I envision a manned mission to Venus. Probably there would be one lone astronaut on the surface due to weight limits to get out of the Venusian gravitational well, as the entire ascent rocket would have to be assembled in low Earth orbit one stage at a time, and then transferred over to Venus. One astronaut plus a limited sampling of Venus rocks would probably be all it could lift.

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#25 2013-12-08 22:45:05

RobertDyck
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From: Winnipeg, Canada
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Re: Powered Spacesuits

Venera landers, by the Soviet Union, used quartz windows. They worked. Venera only failed once coolant ran out. You could use ALON windows: Alumino-Oxy-Nitride. Developed under contract for the US army for windows of tanks. Quartz is crystaline silicon dioxide. Glass is amorphous silicon dioxide with dopants to add strength: soda, lime, etc. They're all immune to acid, but glass would melt on Venus. ALON will withstand the heat and acid, and it's stronger and more impact resistant. No need for diamond.

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