Author Topic: Boeing's CST-100 capsule updates & discussion  (Read 281252 times)

Offline mmeijeri

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1200 on: 03/24/2013 08:10 AM »
Also, at the elevation airplanes fly at, pure oxygen is sufficient for human survival for short periods. At the elevation spaceships travel, pure oxygen isn't sufficient and your blood would boil without a pressure vessel of some sort.

I've read the blood boiling is a myth. Work is being done on flexible spacesuits that aren't airtight and mainly serve to keep the heat in and to keep the astronaut from swelling up. See Space activity suit and BioSuit.
« Last Edit: 03/24/2013 08:56 AM by mmeijeri »
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Online Nomadd

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1201 on: 03/24/2013 12:27 PM »

I've read the blood boiling is a myth. Work is being done on flexible spacesuits that aren't airtight and mainly serve to keep the heat in and to keep the astronaut from swelling up. See Space activity suit and BioSuit.
Skin is not going to maintain any appreciable pressure in the body for long. Blood will start boiling in a very short time in a vacuum. The dissolved O2 will bubble out first, followed by the liquid itself. What do you think "swelling up" means? It's the gasses bubbling out of blood and tissues and the liquid boiling.
 Those suits are also nonsense. Keeping the body pressurized by mechanical pressure on the skin isn't remotely practical. There will always be some area that won't have equal pressure being applied by the suit, and you're back to air pressure taking up the slack.
« Last Edit: 03/24/2013 03:06 PM by Nomadd »

Offline mmeijeri

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1202 on: 03/24/2013 12:32 PM »
Read the references.
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Offline JasonAW3

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1203 on: 03/24/2013 01:24 PM »

I've read the blood boiling is a myth. Work is being done on flexible spacesuits that aren't airtight and mainly serve to keep the heat in and to keep the astronaut from swelling up. See Space activity suit and BioSuit.
You need to learn the difference between science and nonsense. Skin is not going to maintain any appreciable pressure in the body. Blood will start boiling in a very short time in a vacuum. The dissolved O2 will bubble out first, followed by the liquid itself. What do you think "swelling up" means? It's the gasses bubbling out of blood and tissues and the liquid boiling.
 Those suits are also nonsense. Keeping the body pressurized by mechanical pressure on the skin isn't remotely practical. There will always be some area that won't have equal pressure being applied by the suit, and you're back to air pressure taking up the slack.

Personally, I think a mechanical counter pressure suit is quite feasible, so long as some form of conformal mechanical counter pressure system can be comfortably be applied to those regions of the anatomy that would other wise be at risk.

     The solution is surprisingly simple, and I'm rather surprised that no one has thought of it before.  Aerogel padding and padding, cast or formed into those areas that would otherwise require difficult and impractical feats of mechanical design.  Those areas could likewise utilize limited  pressurization, similar in principle to the air bladders found in G suits. Coolant can likewise be laced through the aerogel for comfort, as could a system for 'wicking' away built up moisture as needed.

Just a thought...

Jason
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Offline woods170

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1204 on: 03/24/2013 01:47 PM »
Nomadd thinks he knows better than MIT, NASA and the medical community.

Heck, even I know that most of what he states about the exposure of a human body to a vacuum is incorrect.

By training I'm a biologist. I know from my education that it has been confirmed since the 1970's that exposure to a vacuum does not cause the blood to boil. Skin-, muscle- and connective tissue are very much capable of keeping sufficient pressure on the major bodily fluid systems (blood, lymph and cellular fluid) to prevent those liquids from boiling. Only localized liquid-to-gas expansion occurs in the epidermis. And although that is sufficient to cause extensive damage to the epidermis, it won't kill you. It will not cause your blood to boil. The one thing that will kill you in a vacuum is the effects of suffocation. That is something the crew of Soyuz 11 found out the hard way.
Swelling of tissues occurs because of lack of ambient pressure. The swelling is almost entirely the result of expansion of gas already present in tissue, and not because liquid turns to gas. Side-effects of this gas expansion is localized rupture of capillaries and connective tissue, causing bruising and intense pain.

But, this thread has now gone OT far enough people. Let's stop this discussion about vacuum exposure effects and return to the topic of this thread: Boeing's CST-100 capsule. I'm quite sure Boeing will have a very sturdy and reliable pressure cabin for it's spaceship.
« Last Edit: 03/24/2013 01:50 PM by woods170 »

Online Robotbeat

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1205 on: 03/24/2013 01:55 PM »
Also, at the elevation airplanes fly at, pure oxygen is sufficient for human survival for short periods. At the elevation spaceships travel, pure oxygen isn't sufficient and your blood would boil without a pressure vessel of some sort.

I've read the blood boiling is a myth. Work is being done on flexible spacesuits that aren't airtight and mainly serve to keep the heat in and to keep the astronaut from swelling up. See Space activity suit and BioSuit.
I was referring to the embolism, which is the swelling you're referring to. And you're right the "blood boiling" is a misnomer, but that's kind of what the swelling/embolism is... Air bubbles released from the blood because of the reduce in pressure (like the bends or opening a can of soda), though the vascular pressure helps keep the blood from boiling in the literal sense. But regardless, you can't survive without a pressure suit of some sort, you'll go unconscious very quickly (your blood out-gasses through your lungs, so it's much worse than just holding your breath at sea level).
« Last Edit: 03/24/2013 05:54 PM by Robotbeat »
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Online Nomadd

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1206 on: 03/24/2013 03:04 PM »
 I realize it's popular to try and throw the last word in and declare the topic is drifting.  I never said the blood would boil while the subject was alive. I'm familiar with the jackasses who liked to subject chimps to vacuum to see what would happen. Mengele would have been proud. And, the published ones didn't run for more than 2 1/2 of minutes.
 I was pointing out that the body is a lousy long term pressure vessel, and is going to lose containment before freezing solid. As soon as blood pressure is lost, the blood in the lung tissues will bubbling out CO2. The pressure from that gas will be the main thing keeping those vessels from boiling for a time.
 A suit that could maintain perfect pressure on every square inch of the body and allow movement is not simple by a longshot. Surrounding the body with a layer of gas is far simpler in almost every respect.
 
 Sorry about that cheap shot mmeijeri. You were referring to bad sci-fi movies and  survival in vacuum, and were completely correct. I should have said I was talking about long term, after it didn't really matter to the subject. Obviously, once the body has lost pressure containment, the issue has long since ceased to matter to the vacuumee.
« Last Edit: 03/24/2013 03:14 PM by Nomadd »

Offline mmeijeri

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1207 on: 03/24/2013 03:15 PM »
No problem Nomadd. But let's take this discussion to a new thread since it has little to nothing to do with CST-100, let alone CST-100 updates:

Mechanical counterpressure suits
« Last Edit: 03/24/2013 03:17 PM by mmeijeri »
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Offline Chris Bergin

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1208 on: 03/24/2013 04:03 PM »
I can't split posts into a thread started after the off topic posts started, so use that thread from now on or the posts will be removed.

Online vulture4

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1209 on: 04/01/2013 12:28 PM »
Also, at the elevation airplanes fly at, pure oxygen is sufficient for human survival for short periods. At the elevation spaceships travel, pure oxygen isn't sufficient and your blood would boil without a pressure vessel of some sort.

I've read the blood boiling is a myth. Work is being done on flexible spacesuits that aren't airtight and mainly serve to keep the heat in and to keep the astronaut from swelling up. See Space activity suit and BioSuit.
Blood boiling or "ebulism" most definitely occurs; the skin provides some counterpressure and the blood doesn't boil like water in a kettle, but bubbles form spontaneously in all the major veins and cause the heart pump to become ineffective. In dogs circulation totally stops and the animal loses consciousness.
You can demonstrate this with a beaker of water in a bell jar, Don't use your dog.

Flexible suits have been tested for many years but maintaining uniform counterpressure over the irregularly shaped body is difficult, the tightness of the fabric restricts movement, and wearing a pressure suit continuously for more than a few hours is impossible. The uniqueness of the Soyuz decompression incident (once in over 50 years, and due to an error in design and an extremely improbable event) suggests that it simply isn't feasible. Safety will be better served by simple and reliable pressure cabin systems.
« Last Edit: 04/01/2013 12:32 PM by vulture4 »

Offline docmordrid

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1210 on: 04/01/2013 12:53 PM »
The word is "embolism", not "embulism." It's anything that can block a vessel from a gas bubble to a fat globule, clump of cells or clot. Any intravascular mass.
DM

Offline Patchouli

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1211 on: 04/01/2013 11:34 PM »

Hmm. Tell that to the crew of Soyuz 11.

Remember Soyuz has separate it's orbital module for reentry this is one extra thing that can go wrong.

What failed was a pressure equalization valve between the DM and OM modules.

Ironically the shuttle probably did not really needs suits for reentry since it did not under go configuration changes for reentry.
There were not many scenarios where the vehicle could have lost pressure or would need to be abandoned at altitude that were still survivable.
The CST-100 should have even less such failure modes.

But things could still go wrong during docking operations and a pressure suit can be made to double as an ocean survival suit as the shuttle ACES suit did.

« Last Edit: 04/01/2013 11:46 PM by Patchouli »

Online Robotbeat

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1212 on: 04/02/2013 07:39 PM »
Shuttle, however, had lots of room and having pressure suits was probably a good idea anyway, since Shuttle started out life needing them (first couple flights had ejection seats, which although of limited value perhaps, needed pressure suits to be developed to be at ALL useful).

Just because Shuttle never had a situation where pressure suits during ascent/reentry made a difference between survival and non-survival on any flight doesn't mean it would've never occurred. Shuttle only flew ~150 times.

Also, what in case Shuttle had started to lose pressure in the middle of a mission? the crew would've definitely needed pressure suits for the emergency reentry. Which brings up a question: how long to don the ACES suit in an emergency?
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Offline Patchouli

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1213 on: 04/02/2013 07:49 PM »
Shuttle, however, had lots of room and having pressure suits was probably a good idea anyway, since Shuttle started out life needing them (first couple flights had ejection seats, which although of limited value perhaps, needed pressure suits to be developed to be at ALL useful).

Just because Shuttle never had a situation where pressure suits during ascent/reentry made a difference between survival and non-survival on any flight doesn't mean it would've never occurred. Shuttle only flew ~150 times.

Also, what in case Shuttle had started to lose pressure in the middle of a mission? the crew would've definitely needed pressure suits for the emergency reentry. Which brings up a question: how long to don the ACES suit in an emergency?

The shuttle had a fairly large pressurized volume about 74.3 cubic meters so catastrophic depressurization on orbit within minutes would be highly unlikely.

Instead it most likely would take several hours for the shuttle to leak down esp considering the ECLSS tanks can make up lost gases.

The CST-100 has a smaller volume so a loss of atmosphere would happen faster but again lost cabin air can be replaced to a point.
Perhaps Beoing is planning on carrying extra large O2 and N2 tanks and maybe self sealing walls as their safety margin.

The Soyuz DM pressurized volume is even smaller so a small leak can become dangerous much faster.

The Soyuz 11 crew tried to turn a manual valve to stop it but there just wasn't time.
« Last Edit: 04/02/2013 08:09 PM by Patchouli »

Offline erioladastra

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Re: Boeing's CST-100 capsule updates & discussion
« Reply #1214 on: 04/03/2013 01:29 AM »
Shuttle, however, had lots of room and having pressure suits was probably a good idea anyway, since Shuttle started out life needing them (first couple flights had ejection seats, which although of limited value perhaps, needed pressure suits to be developed to be at ALL useful).

Just because Shuttle never had a situation where pressure suits during ascent/reentry made a difference between survival and non-survival on any flight doesn't mean it would've never occurred. Shuttle only flew ~150 times.

Also, what in case Shuttle had started to lose pressure in the middle of a mission? the crew would've definitely needed pressure suits for the emergency reentry. Which brings up a question: how long to don the ACES suit in an emergency?

Think about the likely failures and you will see that more often than not the suit doesn't help and in certain cases (e.g., water landing) can hinder your survival.  Careful study doesn't really support them and they may only prolong the inevitable.  This is VERY much a case of an emotional reaction vice technical.

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