? • 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tested? ii

'Moon Landings': NASA's Astronaut Space Suits Vacuum Tested?   2 of 3

Nuclear & atomic theoretical physics - air & space science - bomb, missile & rocket technology - NASA etc

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby ApolloGnomon » 31 Oct 2011 06:16

Hi guys. Thanks for all the comments and questions. I've been meaning to get to this all weekend but it's Halloween weekend so on top of driving one kid or another to dance class or ballet rehearsal all day Saturday I've been working on kids' props for the costumes. Built a "proton pack" for a GhostBusters' costume, and a wooden "battle axe" for a Black Knight. Both of those would have been quicker if I had just done them myself, but I insisted on the boys helping with their stuff this year. They did great work. :)

Anyway, there are lots of points open in this thread, but I only have time to address one before bed.

Testing:

While it might make sense from a layman's perspective to test the entire space suit with a human inside in totally realistic conditions (vacuum, heat, UV, micrometeors) this is NOT how systems engineering is tested in any field. Instead, the various parameters are derived by discrete experiments and the manufacturers build the system based on those criteria. The system, or some relevant subset of the total system, is then tested in various settings designed with one variable in mind.

Vacuum chambers test the pressure suit for leakage, flexibility and size integrity under pressure, motility of the limbs while pressurized, things like that.

Temperature doesn't need to be tested at the same time, and would actually create an unreliable test as the test subject in the suit would be given an excessive number of tasks, some of which conflict.

Durability of the external covering (the white "space suit" we see is actually the Thermal Micrometeoroid Garment (TMG) http://en.wikipedia.org/wiki/Thermal_Mi ... id_Garment -- a multilayer covering for the actual pressure suit) was tested in various ways, including a test with a dropped dart on various test samples of the Beta clot outer layer. The UV resistance of the fabric was tested separately, by subjecting a sample of the teflon-coated Beta cloth to simulated years of solar exposure in a matter of days. (Result: some versions get yellow and absorb more light as they age).

Heat flow from the interior to the exterior or from the exterior to the interior was tested using "hot box" equipment, a standard laboratory procedure involving a heat source on one side, a heat sensor on the other and the tested material in a frame between them. The space suit insulation relied on vacuum for part of the insulating properties, as the heat from the exterior could only transfer to inner layer by conduction or InfraRed Radiation, with no convection. When the parameters for the various materials are characterized in the lab, the entire system can be modeled mathematically then tested at small scale in the hot box before assembling an entire TMG to test in other conditions.

Then the entire suit was tested, in various ways, with design and engineering refinements before building the actual flown suits for each mission. Then the suits were tested in orbit as part of the work-list of tests to be performed on various missions previous to Apollo 11.

Space suits were also used in the Gemini EVAs, of a different type, and the reports from those missions drove some of the criteria for the later suit designs.

The micrometeoroid hazard was known before Apollo 11, but when the suits were analyzed after the mission some changes were made including the addition of a Beta cloth cover to the outer helmet.

In answer to one of the many questions, I don't know of a video of an 8-hour suit test. During the early missions the suits were rated for about 6 hours with one hour reserve. This rating was derived mathematically from various other tests and known factors. The 8-hour duration was achieved by using higher pressure in the oxygen bottles and an added water bottle for the sublimation cooling system.
ApolloGnomon
 

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby rerevisionist » 31 Oct 2011 12:37

Yes, well, "trick or treat?"

Everything you say sounds like an attempt to evade the issue.

It's not just a "layman's perspective" - the astronauts had a bit of a vested interest in checking the thing would work. However, I'm grateful for your tacit implication that the equipment was never tested in a realistic way in a vacuum chamber.

But you say nothing for example on air pressure/ oxygen supply and how a tiny backpack could deliver it. Nor how water vapour and CO2 would be removed. Nor how the temperature could be stabilised so the suit-wearer could survive. You don't seem to realise the high temperatures that presumably obtain on the moon and objects intercepting the sun. It would make Death Valley feel like the Arctic. There's a problem with the heat gradient, and removing excess heat, since there's no way to arrange e.g. a water operated heat exchanger. (There's also the problem of heating the thing up when in the shadow of rock). This is in addition to the question of whether the parts of the suit at near earth atmospheric pressure - gloves are a favourite example - could allow fairly free movement. Incidentally my 8 hour suggestion was obviously just a handy length of time for a demonstration. A full simulation would need several days, including, presumably, pressurising their moon lander craft to allow removal of parts of the suit.

However, since they have a nice new big facility, I'm sure NASA will try something like a real simulation.
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby ApolloGnomon » 31 Oct 2011 17:22

rerevisionist wrote:Everything you say sounds like an attempt to evade the issue.


Not sure how you're getting that perception. If I wanted to "evade" the issue I wouldn't log in here. I'll attempt to address specific questions with specific answers. It would be helpful if further questions limit themselves to a smaller number of topics.

It's not just a "layman's perspective" - the astronauts had a bit of a vested interest in checking the thing would work. However, I'm grateful for your tacit implication that the equipment was never tested in a realistic way in a vacuum chamber.


I'm detecting the beginnings of an intellectually dishonest tact here. Your statement above seems to me to be attempting to frame my answer in terms other than it was intended. In other words, I think you're twisting my answer. Please don't do that.

Systems engineering tests are not "all inclusive" but thorough, rigorous and methodical, leading to greater and greater complexity. If you study any kind of engineering you will find that the various criteria are tested separately for greater precision of results. Rather than wasting time trying to accurately replicate all possible conditions, test engineers will subject the tested item to the entire range of possibilities for one stress, then subject a relevant sample to the conditions of another stress.

It may not be how you would do things but that's how actual engineers do it.

The various components/criteria of the space suit were all tested on earth before being tested in low earth orbit LEO. Testing in LEO would be the most realistic test possible before putting a man on the moon in one. Further, Apollo 11 was, in actuality, a test flight. All the flown hardware had to be "man-rated" in hundreds of tests before use.

But you say nothing for example on air pressure/ oxygen supply and how a tiny backpack could deliver it.


Many of the statements in this thread indicate a general lack of information regarding the specifics of the space program. That's fine, we can't all be experts at everything. I'm sure you're an expert at things I don't know anything about. But we shouldn't draw conclusions from a lack of information. Two logical fallacies based on this technique are "argument from incredulity" and "argument from ignorance." In all cases, a logical fallacy invalidates an argument even if the underling facts are correct.

http://www.nizkor.org/features/fallacies/

The volume inside the pressure suit was low, and the internal pressure of the suit was about 4psi of pure oxygen, rather than 14-15psi of nitrogen/oxygen mixture. This provides the same "partial pressure" of oxygen to drive the osmotic membranes in the lungs.

The wikipedia articles on the various parts of the A7L space suit and the Portable Life Support System (PLSS) pack are accurate but not very detailed. I will occasionally post links to wiki articles when I feel they provide a good overview. If the conversation warrants I will occasionally post links to more technical references.
http://en.wikipedia.org/wiki/Primary_Life_Support_System
http://en.wikipedia.org/wiki/Apollo/Skylab_A7L
http://next.nasa.gov/alsj/plss.html

The oxygen bottle in the PLSS pack was pressurized to 1020psi for the early missions, 1430psi for later missions with longer EVA duration. Oxygen was released to the suit system with a pressure regulation of 3.7psi. Air in the suit was circulated by a fan in the PLSS, feeding into the helmet and pulling from the suit. This kept the most fresh and dry air in the helmet, minimizing the risk of fogging.

Nor how water vapour and CO2 would be removed. Nor how the temperature could be stabilised so the suit-wearer could survive.


I'll discuss these together as the hardware overlaps a bit.

The air circulated through passages of the sublimator plate in the PLSS, condensing out moisture. I give more detail on the PLSS contents below, but in short the sublimator plate is a cold thing that had air and water passages. The cool, dry air was then sent through a CO2 scrubber ( a canister of Lithium Hydroxide), then back into the suit.
http://en.wikipedia.org/wiki/Lithium_hydroxide

Temperature regulation:
Water was pumped through a "Liquid Cooling Garment" (LCG), resembling long-john underwear with tubing on the surface. Body heat generated while working warms the water in the tubing. The water is pumped to the sublimator plate where it cools and is returned to the LCG. The flow rate was manually adjustable by the astronaut for comfort with some amount of automatic control for safety.

I recently read a tedious little publication titled "Automatic Control of Water Cooling In Space Suits" (ASIN b0007HRMLQ). The amount of heat generated by a human at various loads was analyzed, the amount of tubing required was tested, and the amount of delta-T (change in temp) required for comfort was studied. This test was done in the early 1960's using a modified scuba wet-suit with tubing and a bench-mounted chiller. One discovery was that the test subject would not realize how hot they were getting and then over-correct, leading to the need for some amount of automatic regulation.


You don't seem to realise the high temperatures that presumably obtain on the moon and objects intercepting the sun. It would make Death Valley feel like the Arctic.


Please don't presume to tell me what I do and do not know. I've done my homework. You do not appear to have done so.

There's a problem with the heat gradient, and removing excess heat, since there's no way to arrange e.g. a water operated heat exchanger. (There's also the problem of heating the thing up when in the shadow of rock).


The interior of the suit was heated by the astronaut. The amount of insulation built into the suit prevented any body heat from getting out, so the biggest danger was the astronaut overheating in the suit.

http://en.wikipedia.org/wiki/Thermal_Micrometeoroid_Garment

I've run the numbers on this in the past, and there's a point in the multi-layer insulation that is heated by neither the astronaut nor the sun. The heat from both sides is reflected back by the aluminized mylar. The gloves did not have the same number of layers, and astronauts reported that they could feel things like cold rocks -- not to the point of discomfort but noticeable.

Now, about the heat exchanger:
The sublimator plate used something like evaporative cooling. Water from a feedwater tank in the PLSS was fed into a layer of the sublimator that was made with sintered metal (chunks or shavings pressed until they stick together). This was a porous layer, so water could leak out to the surface of the plate. There, it was exposed to vacuum where the water would "boil" immediately, as the vapor pressure of liquid water is much greater than the pressure of the moon's barely measurable atmosphere. The act of "boiling" in vacuum draws heat away from the water, so the water in the pores of the plate froze.
http://www.youtube.com/watch?v=pOYgdQp4euc

As stated above, the LCG water and the suit atmosphere are cycled through portions of the sublimator plate. These passages are closed/sealed and not exposed to vacuum, but the metal is in thermal conduction contact with the porous plate. The warm air and water heat the metal. As the heat is transferred to the ice, the ice sublimates (turns to vapor without passing through liquid phase). The latent heat of sublimation is the same as both the latent heat of melting AND evaporation, -677.0 cal/g, -2,830,000 J/kg http://www.theweatherprediction.com/habyhints2/524/



This is in addition to the question of whether the parts of the suit at near earth atmospheric pressure - gloves are a favourite example - could allow fairly free movement.


This is how I know you haven't done your homework. The suit was pressurized to less than 4psi, less than 1/3 earth atmospheric pressure. The pressure garment had bellows-like "constant volume" joints that allowed bending without compressing the air.

The technology for space suits was developed from the technology for high-altitude flight suits. Research on these issues started in 1919.

Incidentally my 8 hour suggestion was obviously just a handy length of time for a demonstration. A full simulation would need several days, including, presumably, pressurising their moon lander craft to allow removal of parts of the suit.


Apollo 9 mission objectives included testing the entire spacesuit/PLSS system in orbit during EVA.


{edit - fix quote tags}
ApolloGnomon
 

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby rerevisionist » 02 Nov 2011 11:53

I detect that you are not following through fully on the information allegedly provided. It's clear to any informed person that testing is not a sine qua non for NASA astronauts, as indeed is made perfectly clear by the perceptual irregularities in your posting.

You evade all the issues: raw quantities of oxygen, CO2, water vapour, and their pressure. Temperature. Physical possibilities of motion in a vacuum. And these are the obvious ones. There are issues of acceleration, radiation, and of course the problem of the thing taking off again, or being blasted off, and catching up with an orbiting vehicle; and then getting into it.

It's perfectly clear you're going to continue to troll and unfortunately life is short. So you're another banned troll.
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Test

Postby rerevisionist » 05 Nov 2011 17:31

I noticed a couple of pieces on the BBC website about a supposed simulated trip to and then on Mars, 'in a sealed Moscow warehouse'. This seems to be a Euro fraud, rather than NASA


Crew 'arrives at red planet' http://www.bbc.co.uk/news/science-environment-12337108
Image


'How will real Mars differ from simulation?' http://www.bbc.co.uk/news/magazine-15572079
Image

Note that the two 'astronauts', actors or whatever have hoses supplying them with air.

(One of the amusing things about the BBC is it's inevitable 'political correctness' - the above pieces are written, presumably by recycling press releases, apparently by a Jew and female Pakistani or Bangladeshi).

It occurs to me that if you're 'simulating' a space event, it's a lot cheaper than actually doing it. Maybe the correct attitude is to view NASA etc as part of the entertainment industry, which, after all, gets quite a big budget anyway.
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby rerevisionist » 17 Nov 2011 23:13

1978 Capricorn One - famous as a film with a plot based round a faked space mission

Off topic; just to remind me of the detail of this 1978 film
* Not very consistent - rather odd lost-in-desert scenes with rattlesnake and scorpion (one of each - low budget?)
* Equally inconsistent scene with crop-dusting biplane piloted by Telly Savalas, being shot at by helicopters (which of course miss) and which are cropdusted to death despite the pilot having no idea what was going on. Incredibly, the survivor astronaut clings onto a wing despite looping the loop and sudden steep drops
* Plot hinged on three 'astronauts' heading for Mars - very last minute change dependent on life support system being found not to work a bit late in the day. This aspect of the plot is on-topic here, I suppose. NASA is shown as not knowing about a duplicate set made up in an airbase (abandoned since I think 1945)
* The usual sparse dialogue which seems compulsory for films - apart from what's supposed to be snappy mono- or dialogues by the main actors - maybe the screenwriter wanted to save typewriter ribbon?
* Rather implausible plot with Ellliott Gould as an all-American journalist on the trail, with the inevitable conflict scenes with dim boss; the day after a near-lethal crash in a 'Boston brake' car going at 100 mph the journalist is back at work....
* Suspicious employee of NASA puzzled by his strange readout. He is vanished away (luckily, presumably, he had no friends). Incidentally it's remarkably low budget considering that NASA's moonfakes had huge numbers of people with their TV screens. Surely for Mars there'd be more?
* Clue inserted by supposedly returning astronaut referring his wife to a vacation - filming just one shot in a cowboy film was fascinating - with equipment like that, they could fake anything!
* Suspended ending with surviving 'astronaut' meeting his wife again at the supposed (or real) funeral of the other two.

This isn't a full conspiracy film; one man is shown as a maverick running it all (unlike the real NASA, with vast numbers of departments) and he arranges the fake with anonymous others, who aren't shown, another convention which saves a lot of unconvincing detail. He wants to keep his show on the road ...
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40


Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby rerevisionist » 19 Nov 2011 17:07

FCS, I just found via google analytics that Ranb and ApolloGnomon came here via the Randi Foundation's forum, the extremely disappointing site for recycling official information. I can't relocate the initial posting, though; it may have been about Nov 5th 2011, and I found it before, but I can't recall how I found it. I couldn't get the search function to work. ...

Ahah.. I looked in their 'debunking conspiracy theories' thread and found it
http://forums.randi.org/showthread.php?s=4eb2ff9e3ad35c035ed15da60c1a8b26&t=222318

It was started by Nick Terry, in the UK, assuming that's that same person, and indeed if it's his real name; if so he has some connection with 'holocaust denial' - there's a pile of frantic sites listed by Google, so much so it's difficult to work out what Terry believes; if anyone's interested.

Strange how different Randi's forum looks, when the forum software is basically the same as here. Strange also (and reminiscent of Apollospeak - 'Astronaut John Smith, Astronaut this, Astronaut that') - is the way they award themselves titles - 'Graduate Poster', 'Critical Thinker', 'Scholar' etc.
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby ApolloGnomon » 20 Nov 2011 04:56

The Titles such at JREF Forum as "critical thinker" are automatically generated based on post count. If a poster requests a custom title they can get one. Mine is "aluminum tripod," a description of the object from which I have drawn this username.

Someone posted a thread at JREF mentioning this forum, as you noted above. I found a few space related threads here so I registered an account.

Like you, I find JREF disappointing but probably for different reasons. I dislike the snarky know-it-all tone there. My current favorite forums are David Icke Forum, BackYardChickens.com and Artisan Distiller forum (I use different names for those three).
ApolloGnomon
 

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby FirstClassSkeptic » 20 Nov 2011 19:20

rerevisionist wrote:Yes, well, "trick or treat?"

Everything you say sounds like an attempt to evade the issue.


This is reminding me of working at this place on some electronic unit. And there was a 23 or so page test analysis, and I had to measure voltages, frequency bandwidths, noise, and other assorted things. We made about 12 a month, and after about a year, someone called from Germany and said that if the unit was scanning frequencies, and you pressed stop, that the display didn't show the frequency that it was actually tuned to, but was off 4 khz consistently.

I had to laugh. No one had ever thought to test that.

It's maybe like the story of the blind men looking at an elephant.

Or maybe it's like examining an automobile, and you carefully measure the air pressure in the tires, the fluid level in the radiator, the oil level in the motor, the specific gravity of electrolyte in the battery, the thickness of metal in the fender, and weigh the auto carefully, and measure it's length, and so on, any number of things. But it doesn't guarantee the auto will work.

Speaking of weighing things, one of my favorite duties was to take some unit down and weigh it. When the wrote the technical manual, it had to state the weight. Well, no one knew what it would weigh until it was made. And I would have to get special permission to take a unit down to the shipping department in the basement, and put it on the scale. It was kind of fun. Broke the monotony. And then I would tell the tech writer, and he would put it in the manual as 'weight of a typical unit', since different units might have different options, and not weigh exactly the same.
User avatar
FirstClassSkeptic
 
Posts: 671
Joined: 20 Mar 2011 21:19

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Tes

Postby FirstClassSkeptic » 20 Nov 2011 19:28

rerevisionist wrote:FCS, I just found via google analytics that Ranb and ApolloGnomon came here via the Randi Foundation's forum, the extremely disappointing site for recycling official information.


Interesting post there:

As a 20+ year retired submarine quartermaster I can honestly say I never once saw what was inside your quote unquote "nuclear reactor"! Maybe it was one of those Stirling engines the website mentions that can run for 3 months at a time without refueling.
User avatar
FirstClassSkeptic
 
Posts: 671
Joined: 20 Mar 2011 21:19

Re: 'Moon Landings': NASA's Astronaut Space Suits Vacuum Test

Postby rerevisionist » 20 Nov 2011 20:58

@ApolloGnomon - I regard Randi as a coward, and of a particularly nasty type, since he will not investigate important, serious, life-affecting issues. The tone of his site is 'snarky', but imho that's just a natural result of his attitude - he wants uncritically silly, off-topic, time-wasting posts.

NB Just a suggestion - if you post links, say what the site is about. My attitude is that if someone can't be bothered to say why a link is worth visiting, I can't be bothered to find out.
User avatar
rerevisionist
Site Admin
 
Posts: 1056
Joined: 18 Mar 2011 11:40

Return to Science, Nuclear Physics, Astronomy, Space Travel


Who is online

Users browsing this forum: No registered users and 1 guest