[X] My Assistant

[Rem31]

Can you walk on Mars (without) protection spacesuit? I think it is possible because it is only my thought. Is this true?

[Guest_BruceMoomaw_*]

No. Before 1964, it was thought that this would be possible -- but in that year, ground-based measurements indicated that Mars' surface air pressure was less than 1% of Earth's (less than 1/10 of what it had previously been thought to be) -- and the next year Mariner 4 solidly confirmed this. It is impossible for a human to maintain consciousness in such a near-space environment without a full-scale pressure suit.

[mcaplinger]

Not currently, no. But I feel compelled to mention that in the 24-hour media blitz following the publication of "Observational Evidence for an Active Surface Reservoir of Solid Carbon Dioxide on Mars" by Malin et al, I made a remark to abcnews.com which they reported thusly:

Michael Caplinger of San Diego's Malin Space Science Systems points out that if the warming were to continue at the same rate (that's a big "if"), Mars could become a nearly inhabitable place for people within 5,000 years or so.

"Rather than wearing a spacesuit, you could get away with wearing just an oxygen mask and a thick parka," said Caplinger, who co-authored a study about the observations in this week's issue of Science. "It would be like standing on top of Everest."

--------------------

Well, OK, I said it, and the person from abcnews.com did the best job by far of reporting the story, but it wouldn't be that much like standing on Everest. If the atmospheric pressure went up 10X to, say,
60-90 millibars, that's still about 4-5 times thinner than the summit of Everest (which is at about 320 millibars.)

It's an interesting question if you could avoid skin hemorrhaging at this pressure. Would a spandex bodysuit under your parka be enough?

[Guest_BillyMER_*]

Not currently, no. But I feel compelled to mention that in the 24-hour media blitz following the publication of "Observational Evidence for an Active Surface Reservoir of Solid Carbon Dioxide on Mars" by Malin et al, I made a remark to abcnews.com which they reported thusly:

Michael Caplinger of San Diego's Malin Space Science Systems points out that if the warming were to continue at the same rate (that's a big "if"), Mars could become a nearly inhabitable place for people within 5,000 years or so.

"Rather than wearing a spacesuit, you could get away with wearing just an oxygen mask and a thick parka," said Caplinger, who co-authored a study about the observations in this week's issue of Science. "It would be like standing on top of Everest."

--------------------

Well, OK, I said it, and the person from abcnews.com did the best job by far of reporting the story, but it wouldn't be that much like standing on Everest. If the atmospheric pressure went up 10X to, say,
60-90 millibars, that's still about 4-5 times thinner than the summit of Everest (which is at about 320 millibars.)

It's an interesting question if you could avoid skin hemorrhaging at this pressure. Would a spandex bodysuit under your parka be enough?

I think you could possibly get some opposition about getting by with just an oxygen mask,like what is success in these circumstances,living for 10 seconds ? :-)

How about deep underground on Mars in a cavity you filled would with oxygen to over come the pressure problem ? That would be an experience to take the first breath on another planet un-aided and smell the aroma of another planets soil even though it not on the surface.

[Bob Shaw]

Mike:

There *have* been interesting experiments with Spandex-like garments as spacesuits (and no, I don't refer here to any UK Conservative MPS and their, ahem, 'hobbies'). The problem is not so much with your body as your head. The human body isn't likely to go bang as such if exposed to low pressures, but you are talking about bleeding and bursting problems at the head end of things (let's leave the bottom end out of this at the moment!). Another problem relates to the direction that oxygen will flow - it'll pass from the blood to the lungs at very low pressures, and you'd become unconscious even though nominally hyper-oxygenated. But, if you can keep the upper body properly sealed, the rest of the body is quite resilient - Spandex and a vapour barrier might well be enough. It does, however, all sound pretty uncomfortable! Temperature control might be fun, too...

Perhaps these sorts of technologies would be more appropriate in agricultural habitats on Mars, where you would have an unbreathable atmosphere of CO2 at (to you and I) low pressures. Such buildings, domes, tents or whatever might well be unsafe to work in without some sort of emergency personal life support (think of a yachtsman's life vest - just enough to get you to safety).

Titan, though...

Bob Shaw

[edstrick]

Open the Pod Bay door, please, Hal....

[mcaplinger]

There *have* been interesting experiments with Spandex-like garments as spacesuits...

Yes, I'm aware of those. But to clarify, I wasn't talking about current martian conditions, where clearly full spacesuits are required, I was talking about a hypothetical situation where the pressure had increased 10x to about 100 mbars. If I'm doing the calculations correctly, that's equivalent to an altitude on Earth of about 17 km or 56,000 feet. That's in the gray area of maybe not needing a full pressure suit -- see http://www.nasa.gov/centers/dryden/researc...ER-2/pshis.html

My thinking was clearly prejudiced by this quote from Heinlein's RED PLANET (1949):

"the colonials maintained about two-thirds Earth-normal pressure indoors for comfort and the pressure on Mars is never as much as half of that... Among the colonials only Tibetans and Bolivian Indians will venture outdoors without respirators and even they will wear the snug elastic Mars suits to avoid skin hemorrhages."

Of course on Heinlein's Mars there was enough oxygen in the atmosphere to be used after compression by his respirators. I assumed pure CO2, and I was off on the pressure by 3x, but it made good copy.

[ljk4-1]

But former US VP Dan Quayle said that Mars has canals, oxygen,
and water - so why shouldn't we be able to walk around on Mars
free as can please?!

http://www.quotationspage.com/quote/526.html

Our politicians know all; they'd never lie to us.

[tty]

But former US VP Dan Quayle said that Mars has canals, oxygen,
and water - so why shouldn't we be able to walk around on Mars
free as can please?!

http://www.quotationspage.com/quote/526.html

Our politicians know all; they'd never lie to us.

I think it was H. L. Mencken who when asked what a tautology is, explained that it means saying the same thing twice, for example "ignorant politician".

tty

[Bill Harris]

Full pressure suits... gone are the days of the innocence of youth.

Years ago one of the hot discussion topics was terr@forming Mars. Is that even a serious topic of nowadays? Besides the formidable task of importing an atmosphere and hydrosphere, can you imagine the chemical reactions that would take place and the amount of time it would take for the planet tosettle into equilibrium conditions?

--Bill

[Bob Shaw]

Full pressure suits... gone are the days of the innocence of youth.

Years ago one of the hot discussion topics was terr@forming Mars. Is that even a serious topic of nowadays? Besides the formidable task of importing an atmosphere and hydrosphere, can you imagine the chemical reactions that would take place and the amount of time it would take for the planet tosettle into equilibrium conditions?

--Bill

Bill:

Over Geological Time, it could be done in the blink of an eye and for minute cost; over Political Time, it'd take an infinite time, and cost at least as many $ (double that if an international effort!). Still, doubling something that's greater than infinity really leaves you with infinity, so that'd be a cost saving, I think. Let's see: potatoe. Yup, sounds right...

Bob Shaw

[Guest_BruceMoomaw_*]

Don't forget that the ultimate culmination of Kim Steanley Robinson's Mars Terraform epic -- after "Blue Mars" -- is the collection of short stories that might be called "White Mars", in which the process goes wrong and refreezes the planet (albeit with a thick atmosphere this time). At the end of that book, they're still trying to figure out how to straighten out the mess again.

[Bill Harris]

After I posted my earlier message I googled terraforming and came up with many hits; I'd say that it may still be a hot topic. However, with today's greater environmental/Green awareness I suppose most would be less hesitant to do that. Recall the agricutural experiment that terraformed the Aral Sea into a playa...

--Bill

[Rem31]

After I posted my earlier message I googled terraforming and came up with many hits; I'd say that it may still be a hot topic. However, with today's greater environmental/Green awareness I suppose most would be less hesitant to do that. Recall the agricutural experiment that terraformed the Aral Sea into a playa...

--Bill

What do i experience when i get out of my (hypothetical) Marslander (without) space(pressure)suit ,and only with my trouser and a t shirt or sweater and step on the Mars surface and begin to walk? Do i survive it?

[Bob Shaw]

What do i experience when i get out of my (hypothetical) Marslander (without) space(pressure)suit ,and only with my trouser and a t shirt or sweater and step on the Mars surface and begin to walk? Do i survive it?

Well...

...depending on the circumstances before you get out (pressure, oxygen content in the air within the lander), and assuming you remember to SCREAM to equalise pressure (just like submariners exiting their stranded vehicles are instructed to do), you might be conscious, but none to happy, for 30 seconds or so. You're unlikely to go bang, and you might well be reviveable for a few minutes after that, but with a massive lung oedema, likely leading to early death. 2001-style *brief* exposure to near zero pressure is no problem, but shut that door ASAP!

Speaking of doors, if experience on the Moon is anything to go by, it may take ages to decompress the cabin enough to open the door, in which case you'll have passed out before leaving the spacecraft.

Unsuited sprints on Mars bases from big, fast-opening airlocks to other, fast-closing ones are actually quite feasible, and could be great fun, unless they are not fun, in which case they'd be verrrrry little fun at all!

Oh, for Kemlo when you need him!

Bob Shaw

[Guest_BruceMoomaw_*]

Let's not forget that you'll come down with one hell of a case of hypothermia, given that the average surface temperature on Mars is -56 deg C -- and that you'll also come down with one hell of a case of sunburn even given Mars' greater distance from the Sun, since it has no ozone layer. Fun all around. Clearly Martian Streaking will be one of the major sports of the future Solar System-wide civilization.

[Rem31]

How long takes it before i die ,when i step on Mars without a pressuresuit? Is it painfull? And what about bloodboiling? I think that the blood in the body is going to boil when stepped (unprotected) on Mars. Can you explain this?

[Bob Shaw]

Let's not forget that you'll come down with one hell of a case of hypothermia, given that the average surface temperature on Mars is -56 deg C -- and that you'll also come down with one hell of a case of sunburn even given Mars' greater distance from the Sun, since it has no ozone layer. Fun all around. Clearly Martian Streaking will be one of the major sports of the future Solar System-wide civilization.

Bruce:

No, hypothermia won't be a problem - look at the fun and games that silly boys get up to at the south pole on Earth. You're talking about a few seconds of exposure in an environment where heat transfer is all about radiation (no wind to chill you) and, in any case, hypothermia is all about core body temperatures!

As for the UV... ...would 30 seconds worth of exposure burn you, especially if you'd splashed factor 20 sun blocker all over you?

I'd be more concerned about an allergic reaction to Martian dust, to be honest!

I *do* like the idea of Martian streaking, though. Or Lunar Streaking. Sorta puts a whole new light on how the unmanned spaceflight community should respond to the triumphal opening (by President-for-Life Dubya IV) of the 'Neil 'n' Buzz' theme park in 2069...

Oh, I'm gonna have nightmares now...

Bob Shaw

[Guest_BruceMoomaw_*]

How long takes it before i die ,when i step on Mars without a pressuresuit? Is it painfull? And what about bloodboiling? I think that the blood in the body is going to boil when stepped (unprotected) on Mars. Can you explain this?

No, your blood won't boil -- Arthur C. Clarke laid that cliche to rest in a story called "Take A Deep Breath" all the way back in the mid-1950s (which was later used as the basis for David Bowman's spacesuit-less return to his ship's airlock in "2001"). And as early as 1964, the Air Force did some vacuum chamber experiments on chimps (naturally) establishing that they could survive as long as 1-2 minutes in a vacuum without serious brain damage. (No word on how many chimps they killed or maimed while learning this.) But, while your blood certainly won't boil, it is fatal after a very short time -- and I imagine it's pretty painful.

Bruce:


I *do* like the idea of Martian streaking, though. Or Lunar Streaking. Sorta puts a whole new light on how the unmanned spaceflight community should respond to the triumphal opening (by President-for-Life Dubya IV) of the 'Neil 'n' Buzz' theme park in 2069...

Oh, I'm gonna have nightmares now...

Bob Shaw

Yes, particularly if I'm in them.

[Rem31]

Bruce:

No, hypothermia won't be a problem - look at the fun and games that silly boys get up to at the south pole on Earth. You're talking about a few seconds of exposure in an environment where heat transfer is all about radiation (no wind to chill you) and, in any case, hypothermia is all about core body temperatures!

As for the UV... ...would 30 seconds worth of exposure burn you, especially if you'd splashed factor 20 sun blocker all over you?

I'd be more concerned about an allergic reaction to Martian dust, to be honest!

I *do* like the idea of Martian streaking, though. Or Lunar Streaking. Sorta puts a whole new light on how the unmanned spaceflight community should respond to the triumphal opening (by President-for-Life Dubya IV) of the 'Neil 'n' Buzz' theme park in 2069...

Oh, I'm gonna have nightmares now...

Bob Shaw

But why are the apollo astronauts on the Moon not Sunburned? Strange that you get Sunburned on Mars in 30 seconds ,but on the Moon the astronauts where not getting Sunburned. Can you explain this?

[Bob Shaw]

But why are the apollo astronauts on the Moon not Sunburned? Strange that you get Sunburned on Mars in 30 seconds ,but on the Moon the astronauts where not getting Sunburned. Can you explain this?

Bruce and I have been discussing the prospects for (brief) Martian surface activity *without* spacesuits. He went so far as to bring up the subject of doing it without underwear, which got me started on sun cream.

The Apollo guys had underwear, as well as those big white things, with the helmets.

Bob Shaw

[Rem31]

No, your blood won't boil -- Arthur C. Clarke laid that cliche to rest in a story called "Take A Deep Breath" all the way back in the mid-1950s (which was later used as the basis for David Bowman's spacesuit-less return to his ship's airlock in "2001"). And as early as 1964, the Air Force did some vacuum chamber experiments on chimps (naturally) establishing that they could survive as long as 1-2 minutes in a vacuum without serious brain damage. (No word on how many chimps they killed or maimed while learning this.) But, while your blood certainly won't boil, it is fatal after a very short time -- and I imagine it's pretty painful.
Yes, particularly if I'm in them.

Why is it that your blood is not going to boil? Water is boiling too by the low pressure on Mars?

[Bob Shaw]

Why is it that your blood is not going to boil? Water is boiling too by the low pressure on Mars?

Because your blood is inside your body. Water will certainly evaporate from exposed skin, and any moist parts of the human body will tend to dry up, but in the short term there's more than enough water inside you to replace any that's lost at the surface.

People just don't go POP! when exposed to zero pressure, though they certainly don't survive for very long. They don't die at once, though, which gives rise to all sorts of fun and games (in theory).

Bob Shaw

[ljk4-1]

No, your blood won't boil -- Arthur C. Clarke laid that cliche to rest in a story called "Take A Deep Breath" all the way back in the mid-1950s (which was later used as the basis for David Bowman's spacesuit-less return to his ship's airlock in "2001"). And as early as 1964, the Air Force did some vacuum chamber experiments on chimps (naturally) establishing that they could survive as long as 1-2 minutes in a vacuum without serious brain damage. (No word on how many chimps they killed or maimed while learning this.) But, while your blood certainly won't boil, it is fatal after a very short time -- and I imagine it's pretty painful.
Yes, particularly if I'm in them.

Speaking of Mr. Clarke, he also wrote a story not too long ago about an
actual running race on the Moon. The main character wore a skin-tight
suit so that he could run faster.

Knowing how ACC tries to be as scientificially and technically accurate as
possible, does anyone who has the story handy have the details on how it
was made and how it kept the occupant pressurized? Thanks.

[Guest_BruceMoomaw_*]

Why is it that your blood is not going to boil? Water is boiling too by the low pressure on Mars?

Actually, water does NOT boil dramatically on Mars -- in fact, Mars' air pressure, low though it is, is very close to the level at which water CAN remain stable in liquid form on the surface. The University of Arkansas' Derek Sears, in fact, has been running some experiments recently to find out just how fast it WOULD evaporate on Mars, and has found that it evaporates at a rate as low as just a few millimeters per minute -- and slower than that if it's briny. (Another study has located a few low-altitude parts of Mars' surface on which water can actually stay liquid on Mars' surface for weeks at a time, before seasonal temperature changes make it either freeze or evaporate.)

The fact that Mars' air pressure is so close to the so-called "triple point" at which liquid water can exist may not be coincidence. One theory suggests that, just as Earth has a natural "carbonate thermostat" process that tends to keep its surface temperature in the range at which liquid water can exist, Mars may have a natural "carbonate air pressure regulator" -- that is, if its remaining low-intensity volcanoes belch out enough new CO2 to raise its air pressure to the point at which liquid water can exist, that liquid water tends to make some of the CO2 react with subsurface minerals and turn into carbonates, lowering the air pressure back to the threshold level again until more CO2 leaks out of the volcanoes. This theory, however, is still uncertain -- it may really BE coincidence.

And while water really does boil in the lunar vacuum, it's been pointed out -- by Arthur C. Clarke and others -- that the human body's skin and internal mucous membranes are really a pretty good pressure seal; internal gas leaks out of the human body fairly slowly even in a vacuum. Thus a vacuum will knock you unconscious in a few seconds -- and kill you in a minute or so -- but the internal pressure will never leak out of your body fast enough for the water in your blood to actually boil.

[Guest_BruceMoomaw_*]

Derek Sears' recent findings on the rate of liquid-water evaporation on Mars can be found at
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2112.pdf
http://www.lpi.usra.edu/meetings/lpsc2004/pdf/2159.pdf

I was wrong in saying that he reported evaporation rates of "a few millimeters per minute" -- it was actually just 1-2 mm PER HOUR. As I say, Mars is teetering on the very brink of having air pressure high enough for liquid water to exist stably there at the right temperature -- and, according to Robert Haberle, there are a few low-altitude places where seasonal temperature conditions do allow it to exist for weeks at a time: http://www.agu.org/pubs/crossref/2001/2000JE001360.shtml

[dvandorn]

I'd be more concerned about an allergic reaction to Martian dust, to be honest!

With all of those powerful oxidants (perhaps peroxides) so ubiquitous in Martian soils, I'm wondering what will happen the first time some of that dust hits the mucous membranes of a human being's nose and mouth.

At any rate, with all those sulphates around, the dust will likely stink to high heaven. If you want to colonize Mars, you better be able to get used to the smell of rotten eggs...

-the other Doug

[Bob Shaw]

I think a lot of the fluff around about water boiling away on the surface of Mars, or people's blood boiling if exposed to zero pressure, goes back to two things: bad early science-fiction, and that photograph (taken at Holloman AFB?) of the guy in the pressure suit in the evacuated chamber, holding a beaker of water which is furiously boiling. Right or wrong, those are the cultural memes which have infected us!

Bob Shaw

[paxdan]

Speaking of Mr. Clarke, he also wrote a story not too long ago about an
actual running race on the Moon. The main character wore a skin-tight
suit so that he could run faster.

Knowing how ACC tries to be as scientificially and technically accurate as
possible, does anyone who has the story handy have the details on how it
was made and how it kept the occupant pressurized? Thanks.

The story was "the hammer of god" and the character was 'Robert Singh'

it is a skin suit with a bubble helmet designed only for use at night... from p46.

'sheathed in two body-tight garments - one active, one passive. the inner one made of cotton, enclosed him from neck to ankle, and carried a closely packed network of narrow, porous tubes, to carry away perspiration and excess heat. Over that was the tough but extremely flexiable protective outer suit, made of a rubber like material, and fastened by a ring-seal to a helmet."

he gets frost bitten feet and is beaten at the last by Robert Steel (a robot).

Don't forget that the ultimate culmination of Kim Steanley Robinson's Mars Terraform epic -- after "Blue Mars" -- is the collection of short stories that might be called "White Mars", in which the process goes wrong and refreezes the planet (albeit with a thick atmosphere this time). At the end of that book, they're still trying to figure out how to straighten out the mess again.

The collection of short stories by KSR is called 'The Martians'. The culmination of that is a short called 'Purple Mars' in which the terraforming has been successfull.

'White Mars' was written by Brian Aldiss in collabaration with Roger Penrose and was very much a retort to KSR's mega terraforming.


Gregory Benford's "The Matian Race" contains a section where a character runs from a ruptured greenhouse to a Hab in Martian conditions. It was a highlight of the book.

[mcaplinger]

The collection of short stories by KSR is called 'The Martians'.

It's also not necessarily connected to the Mars trilogy. The novella "Green Mars" which is collected in THE MARTIANS is in something of an alternate universe from that of the trilogy, according to KSR.

[JRehling]

I don't know how many ghoulish incidents there are that have accidentally probed this issue for us, but I recall the incident in October 1999 in which a plane carrying golfer Payne Stewart and four others took off from Orlando, then apparently depressurized, killing them while the plane remained on autopilot until it ran out of fuel and crashed in South Dakota. Not much is known about the incident because the crash destroyed everything, but it seemed to be a case where sudden exposure to the atmosphere at 30,000 to 39,000 feet left the pilot without recourse to radio anyone on the ground before losing consciousness. Of course, he may have been distracted by other aspects of the situation and realized that calling the ground wasn't going to benefit the plane in the short run.

I read in a report on that incident that at 39,000 feet, the duration of one's consciousness is about 6-12 seconds. Once that last breath got pulled from your lungs, your streak across the surface of Mars might go sour pretty fast.

Another note: people have summited Everest without bottled oxygen. Now imagine you did have bottled oxygen; that would give you the same partial pressure as those climbers face at a pressure of only 70 millibars. And those climbers, of course, are doing something VERY HARD at the same time. It would seem to me that if you had 70 millibars of pure oxygen (or partial pressure thereof, and not enough CO2 to foul you up), you could go for a stroll, or maybe even a strenuous hike. When I say, "You", of course, I mean an elite high-altitude climber.

[dvandorn]

The research I've seen on this issue indicates that, even if you oxygenate your blood as well as possible (i.e., get yourself on the verge of hyperventilation), you can maintain consciousness in a vacuum or near-vacuum for anywhere from 15 to 30 seconds. Doing something strenuous that pulls the oxygen out of your blood faster (like running from one pressurized space to another) would tend to decrease your available time of consciousness.

So, in other words, the scene in 2001 *is* plausible, but sprinting on Mars for more than 20 or 30 feet probably isn't.

Someone should suggest this as a project for the Mythbusters, see if they can bust it or confirm it.

-the other Doug

[Bob Shaw]

Ooh. I'm not sure if I'd like to see somebody try to *seriously* stroll about on the surface of Mars without a spacesuit - I think you'd rapidly face a number of physiological brick walls, even if you were no couch potato. Even earache could be pretty disabling...

But, a quick sprint...

22-year-old Jamaican Asafa Powell broke the 100-metre record in Athens in 2005, doing the run in 9.77 seconds. And, perhaps of more interest to the UMSF crew, in 2004 Philip Rabinowitz entered the Guinness Book of World Records by clocking 30.86 seconds over 100 metres, demolishing the previous record of 36.19 set by the Austrian Erwin Jaskulski. Of course, both these athletes were 100-year-olds!

So, let's assume that nobody going to Mars will be able to equal the running ability of a top athlete - but could we match a centenarian? Far from 20-30 feet being doable, I think 20-30 metres is quite feasible for a reasonably healthy person, especially when it's in a 1/3G environment. Athletes should do even better.

If you're up and running as the big loading bay airlock door flips up then all the biological price/performance curves are still in the green - you're oxygenated, you're moving, and there's a chap with an oxygen bottle just a few yards away. Real show-offs will try to get ahead of the crowd by pole-vaulting (unless they're stopped in time by the Interplanetary Olympic Committee)!

Bob Shaw

[tty]

I don't know how many ghoulish incidents there are that have accidentally probed this issue for us, but I recall the incident in October 1999 in which a plane carrying golfer Payne Stewart and four others took off from Orlando, then apparently depressurized, killing them while the plane remained on autopilot until it ran out of fuel and crashed in South Dakota. Not much is known about the incident because the crash destroyed everything, but it seemed to be a case where sudden exposure to the atmosphere at 30,000 to 39,000 feet left the pilot without recourse to radio anyone on the ground before losing consciousness. Of course, he may have been distracted by other aspects of the situation and realized that calling the ground wasn't going to benefit the plane in the short run.

I read in a report on that incident that at 39,000 feet, the duration of one's consciousness is about 6-12 seconds. Once that last breath got pulled from your lungs, your streak across the surface of Mars might go sour pretty fast.

That kind of accident is typically NOT caused by explosive decompression, which is a pretty dramatic thing, but rather by a slow loss of pressurization. Slow hypoxia is very insidious and there have been any number of accidents where aircrew have lost consciousness without being aware of what was happening.
There was a recent case where a cypriot B737 took off with the automatic pressurization off and the crew and all passengers lost consciousness (the aircraft ultimately crashed). Admittedly the crew must have been pretty inept since they must both have skipped a checklist item and misunderstood or disregarded a pressurization warning during the climbout, but it shows that the symptoms are not obvious.

tty

[Guest_BruceMoomaw_*]

In fact, a former Air Force pilot recently sent a letter to our local newspaper proposing that, if we really want to carry out the death penalty (which he opposes) as humanely as possible, then using either a gradual vacuum chamber or a nitrogen-filled chamber is the best way to do it, because such deaths produce absolutely no pain or warning sensations of any kind -- our suffocation reflex is triggered by excessive CO2, not by inadequate oxygen. (Just before the first Space Shuttle flight, two pad technicians were tragically killed for just this reason -- they entered a chamber inside the Shuttle engine compartment that was flooded with nitrogen without their knowing it, and both quietly passed out and suffocated before they or anyone else knew what was happening.)

[JRehling]

or a nitrogen-filled chamber is the best way to do it, because such deaths produce absolutely no pain or warning sensations of any kind

Nitrogen, my old friend, after breathing 78% of you for all my life, you do me in now. Et tu, N2? Ack. Thud.

[MichaelT]

I always found the following NASA link very interesting:
Human Body in a Vacuum
There are also some references.

Though your blood will not boil this might still happen:
"The saliva on your tongue might boil, however."

So, if you have a tickling sensation on your tounge, beware!

Michael

[Rem31]

And what happens when you are trying to breath in on the Moon or on Mars (unprotected) without pressuresuit? And what is the pressure (in) a airplane during a passenger flight at 36,000 feet high? And what happens when decompression occurs then? (totally loss of pressure) inside the cabin of the airplane.

[Bob Shaw]

And what happens when you are trying to breath in on the Moon or on Mars (unprotected) without pressuresuit? And what is the pressure (in) a airplane during a passenger flight at 36,000 feet high? And what happens when decompression occurs then? (totally loss of pressure) inside the cabin of the airplane.

Breathing does sound iffy, I agree - if you have a mask over your mouth and nose and have an internal pressure of a few pounds then your ears and eyes would give you absolute hell. Perhaps an eye-band with sealed goggles and pressure-blanced earplugs would work, but it still doesn't sound like much fun, and if it went at all wrong it'd be crippling. A proper Flash Gordon bubble helmet, though, might just work (and could solve the UV problem). Add rubber swimming-trunks (don't ask me to spell out why that might be a *good* idea), and we're heading for comic-book heaven!

As for the questions you raised, most of them are answerd on the NASA site mentioned in the post before this one. The pressure in a 36,000 feet actual altitude aeroplane cabin can vary, but 10,000 feet is probably about right (it actually depends as much on the flight profile as anything). Total decompression then would result in ambient air pressure being the norm, and breathing being assisted via those little drop down cup masks they tell you about but never let you play with. You don't go BANG! You don't bleed from every orifice! You don't fall over dead!

Bob Shaw

Attached thumbnail(s)

 

[tty]

And what is the pressure (in) a airplane during a passenger flight at 36,000 feet high? And what happens when decompression occurs then? (totally loss of pressure) inside the cabin of the airplane.

The pressure is about equal to being at 10,000 feet altitude. The reason it is kept at this level and not at sealevel pressure is to save power and decrease the strain on the pressure shell (which is very considerable). This altitude (10,000 feet) is normally quite safe for any reasonably healthy person (though I have seen people get altitude sickness at 11,000-12,000 feet).

If You have an explosive decompression there is one hell of a bang and the cabin fills with fog (since the thin air can't suspend nearly as much water vapour). The emergency oxygen masks should drop down, and usually they do. The crew (which have a separate, better and rather more reliable oxygen system) initiates an emergency descent. Normally this is fast enough to avoid casualties even if the oxygen system does not deploy. It is very rare for fatalties to occur in decompression accidents.
As a matter of fact in the case of the B737 accident I mentioned in an earlier post apparently most of the people were still alive but unconscious when the plane crashed and this was after a long flight at high altitude without pressurization.

tty

[MichaelT]

the cabin fills with fog (since the thin air can't suspend nearly as much water vapour).

It's a widely believed myth that air has a holding capacity for water vapor (even widely tought!). Due to the depressurisation the pressure of the air drops and, thus, the temperature of the gas water vapor. This finally leads to condensation.
For a thorough explanation go to the Bad Meteorology Page.

Michael

[Spacely]

Hey, guys. Long time lurker, first time poster.

This thread caught my eye and I thought I'd jump in with this "What if..."

Let's say you're wearing a parka, thick pants, goggles, ear plugs, an oxygen mask, and lying flat on your back in the Hellas Basin in mid-summer. Could you conceivably lay their all day (10AM to 5PM) without ill effects, or are the UV rays/solar radiation, etc. going to make you sick within hours?

[edstrick]

You die pretty fast. You're blood's above the boiling point, at any rate. Even with pressures high enough your blood doesn't boil, and with 100% oxygen, if the oxygen content in the air you breathe is too low, you pass out and die anyway.

There has to be documentation on "stay-concious" 100% oxygen pressure limit and "not die" pressure limit and it should be pretty findable, but it's above any plausible geologically recent martian surface pressure, i'm pretty sure. (not including transient atmospheres after major impacts or eruptions, etc.)

[Bob Shaw]

Let's say you're wearing a parka, thick pants, goggles, ear plugs, an oxygen mask, and lying flat on your back in the Hellas Basin in mid-summer. Could you conceivably lay their all day (10AM to 5PM) without ill effects, or are the UV rays/solar radiation, etc. going to make you sick within hours?

You forgot the rubber underpants.

Bob Shaw

[Rob Pinnegar]

You die pretty fast. You're blood's above the boiling point, at any rate. Even with pressures high enough your blood doesn't boil, and with 100% oxygen, if the oxygen content in the air you breathe is too low, you pass out and die anyway.

Hmm. So if your blood is above the boiling point, that means your lungs can't get any oxygen into your bloodstream?

[RNeuhaus]

Hmm. So if your blood is above the boiling point, that means your lungs can't get any oxygen into your bloodstream?

As I understand is, since the Mars has very low atmosphere presure, about 6-7 milibars comparing to around 1000 milibats at the see level (depending to the sessons) and the blood will evaporate and hence, the lung won't get any oxygen. I am not accounting the influence of low temperature to hold a little further the boiling point.

Rodolfo

[tty]

Have a look at this:

http://www.dsls.usra.edu/meetings/bio2001/pdf/140p.pdf

That Buck Rogers suit might be possible after all....

tty

[Bob Shaw]

Yes - very interesting, it's good to get some real figures on the physiology front rather than the physics!

The test subject does, however, look rather too pleased with himself for my liking - like a big boy who has *finally* been given the birthday present he should have had when he was eight!

Yup, that's me: jealous!

Bob Shaw

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[deglr6328]

One can scarcely imagine the unspeakably ghastly horrors which await the tailoring of these suits to the current American populace. *shudder*

[Guest_BruceMoomaw_*]

As I understand is, since the Mars has very low atmosphere presure, about 6-7 milibars comparing to around 1000 milibats at the see level (depending to the sessons) and the blood will evaporate and hence, the lung won't get any oxygen. I am not accounting the influence of low temperature to hold a little further the boiling point.

Rodolfo

Even in a pure vacuum, the blood won't boil -- the body's tissues (even on exposed mucous membranes) serve as a pretty good pressure seal -- but the oxygen will diffuse out of it VERY fast into the vacuum, which is why an oxygen mask alone isn't enough to allow survival in such an environment. But Mars' air pressure -- tiny though it is -- is very close to the level at which liquid water CAN survive; Derek Sears' tests at the U. of Arkansas suggest an evaporation rate as slow as 1 mm/hour! So, presumably, you could survive distinctly longer on Mars than in a pure vacuum -- but we're still talking about oxygen diffusing out of the blood into that thin air very fast. I can't see any human being able to survive in such an environment (even unconscious) more than a few minutes.

[Spacely]

Even in a pure vacuum, the blood won't boil -- the body's tissues (even on exposed mucous membranes) serve as a pretty good pressure seal -- but the oxygen will diffuse out of it VERY fast into the vacuum, which is why an oxygen mask alone isn't enough to allow survival in such an environment. But Mars' air pressure -- tiny though it is -- is very close to the level at which liquid water CAN survive; Derek Sears' tests at the U. of Arkansas suggest an evaporation rate as slow as 1 mm/hour! So, presumably, you could survive distinctly longer on Mars than in a pure vacuum -- but we're still talking about oxygen diffusing out of the blood into that thin air very fast. I can't see any human being able to survive in such an environment (even unconscious) more than a few minutes.

Fascinating. Everyone talks about the likes of Titan being a strange world, but imagine how strange it would be to walk on Mars during noon on summer day, see a puddle of liquid water, measure temperatures of 50F, and yet, still know that if you take off your suit, you're dead in minutes. Hell, as is, seeing rover pics of a dry desert Mars doesn't make it seem all that inhospitable! It's the deadliest cozy spot in the solr system.

[edstrick]

The triple point of water where ice, liquid and vapor are in equilibrium, is at 6.3 or 6.7 millibars pressure. That's ICE-WATER. So a beaker full of ice water won't boil in the lowlands but will boil on the Tharsis plateau. However, blood is normally quite a bit above freezing.... nominally 98.6 F. So a bucket-of-blood (Is this another cheapo mars skiffy movie?) will boil anywhere on Mars unless it's had time to chill down.

What is the "ketchup-count" on this thread, anyway?

[lyford]

That Buck Rogers suit might be possible after all....

Despite all the worry about Moon dust ruining the outside of suits and needing an airlock to prevent dust entering the capsule, the mind reels at the prospect of the dangers presented by the INSIDE of these skin tight pressure suits after a hard day's work on Mars. Phew!

Though there are some advantages to a skin tight pressure suit, as this other research program from the 1960's demonstrated:

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[Bob Shaw]

With a little effort, and the unknowing assistance of Michelin, I have simulated the appearance of a circumferentially-challenged space traveller in a skinsuit.

Be warned: Before you Luke, a pretty sight it is not, oh no.

Bob Shaw

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