question about mars

[Third Eye Open]

The atmospheric pressure of mars is much lower than that of earth.
Is it so much lower that it would instantly kill a human outside without a space suit, such as the famous scene from the movie 'Total Recall'?

Would it be possible to stand on mars with nothing but an oxygen tank and mask? To dig in the dirt with my bare hands?

 

[R.Mackey]

Surface conditions on Mars would be fatal for a variety of reasons.

You wouldn't be able to hold an oxygen mask on your face with the nearly 15 PSI differential. Surviving there without a suit would be like surviving in a balloon lofted to about 30 km altitude -- not feasible. If somehow you did, exposed skin would rapidly freeze.

Mars is susceptible to solar radiation storms, enough so that a sufficiently bad one would kill you without shielding.

What atmosphere Mars has is about 95% CO₂. Any exposed water -- say your eyes, your open mouth -- would have a hard time deciding whether to freeze, evaporate, or absorb CO₂ to produce carbonic acid.

Having said all this, Mars is closer by far to habitable conditions than any other known non-terrestrial environment. I hold out some hope that radical extremophiles could live there, and indeed may live there as we speak. As for you and I, though, not going to happen any time soon.

 

[uk_dave]

I hold out some hope that radical extremophiles could live there, and indeed may live there as we speak. As for you and I, though, not going to happen any time soon.

NEWSFLASH- "NASA scientist says Martians exist!!"

 

[Trent Wray]

I recently came upon some CT's claiming the martian "sky" is actually blue to blue-grey and not tinted red as most would think. The idea was that NASA color corrected the images to reflect a red sky, when in actuality it would be much different. Any truth to this or not?

And somewhat o/t --- would it be possible to station a long-term habitable ship orbiting Saturn and use Titan more or less for harvesting fuel to power the ship's resource needs?

 

[shadron]

You might notice that on top of every lander we've dropped onto Mars is a color wheel in view of the cameras. That color wheel is used to correct the various filter coefficients so that they are properly represented in the final renderings.

When the first Viking lander landed on Mars in July of 1976 The first panorama it sent back had a nice blue sky shown. That was followed about a day later by a corrected print with the pink/orange sky we've grown to love, and apologies from the imaging team for the confusion. Ever since then the sky has been pink, the result of orange dust in the atmosphere. Presumably, then, the color of the sky would differ depending on the amount of dust present. It might actually be blue when viewed straight upwards.

 

[Trent Wray]

You might notice that on top of every lander we've dropped onto Mars is a color wheel in view of the cameras. That color wheel is used to correct the various filter coefficients so that they are properly represented in the final renderings.

When the first Viking lander landed on Mars in July of 1976 The first panorama it sent back had a nice blue sky shown. That was followed about a day later by a corrected print with the pink/orange sky we've grown to love, and apologies from the imaging team for the confusion. Ever since then the sky has been pink, the result of orange dust in the atmosphere. Presumably, then, the color of the sky would differ depending on the amount of dust present. It might actually be blue when viewed straight upwards.

Yeah I started to read about the color wheel on the cameras, but then the article I was perrussing (sp?) started going into color theory and how we perceive color and so on and so forth and the drooling from my mouth commenced and I figured I didn't care that much afterall

But the overall thing was that originals with the blue sky were incorrect (i.e. the color wheel revealed the inconsistencies with how we perceive color on earth)? And so the Total Recall coloring was the real deal, given the amount of dust present at the lower levels in the atmosphere? Is this correct?

I thought Quade had finally melted the ice caps so we could all grow flowers there now, and that NASA was covering it up ...

 

[Jack by the hedge]

But the overall thing was that originals with the blue sky were incorrect (i.e. the color wheel revealed the inconsistencies with how we perceive color on earth)? And so the Total Recall coloring was the real deal, given the amount of dust present at the lower levels in the atmosphere? Is this correct?

I don't think it was anything to do with inconsistencies in the way we perceive colours, it was just that the colour balance hadn't been calibrated. The first pictures were issued with an inaccurate colour balance which showed a familiar looking blue sky, but when the colour chart was photographed it became clear that there was really more red light and less blue. So the corrected images show what we would see if we were there; the sky is pinkish-grey.

 

[Mark6]

I recently came upon some CT's claiming the martian "sky" is actually blue to blue-grey and not tinted red as most would think. The idea was that NASA color corrected the images to reflect a red sky, when in actuality it would be much different.

First, it is nonsense.

Second, ask the CT's what would be the purpose of this particular deception? I do not expect a convincing answer, but possibly an entertaining one.

 

[Mark6]

The atmospheric pressure of mars is much lower than that of earth.
Is it so much lower that it would instantly kill a human outside without a space suit, such as the famous scene from the movie 'Total Recall'?

I never saw the movie so can't tell, but people in vacuum do not explode, and do not die instantly. In vacuum a person would remain conscious for 10-15 seconds, and would die about a minute later (The famous scene in "2001: Space Odyssey" where Bowman enters airlock without a helmet is actually possible). Mars air is close enough to vacuum as to make no difference.

Would it be possible to stand on mars with nothing but an oxygen tank and mask?

Not for long. Even if your mask were secured well enough to stand up to 15 psi pressure difference, you would suffer severe bends within minutes.

To dig in the dirt with my bare hands?

Oddly enough, yes. Volunteers had spent as much as 30 minutes with both hands in a vacuum chamber, with no worse effects than some swelling. So if your space suit had airtight cuffs, then yes you could stick your hand into dirt on Mars. Or on the Moon.

 

[Trent Wray]

First, it is nonsense.

Second, ask the CT's what would be the purpose of this particular deception? I do not expect a convincing answer, but possibly an entertaining one.

If I remember it was:

* to keep "us" from understanding how habitable life on mars actually was
* they faked the martian rover expeditions on earth and accidentally leaked the photos showing this
* NASA is a conspiracy agency in general, yada yada yada

 

[Ziggurat]

The atmospheric pressure of mars is much lower than that of earth.
Is it so much lower that it would instantly kill a human outside without a space suit, such as the famous scene from the movie 'Total Recall'?

Would it be possible to stand on mars with nothing but an oxygen tank and mask? To dig in the dirt with my bare hands?

Bad things can happen to the human body if the ambient pressure drops too fast. In particular, you can develop decompression sickness, commonly referred to as "the bends". But the bends doesn't resemble that Total Recall scene. You aren't going to get anything even remotely resembling that. Note, though, that the problem is the rate of change in pressure. If given time to adapt, the human body can tolerate pressures well below 1 atmosphere. I'm not sure what would happen at Mars pressures, which are only about 1% of Earth's atmosphere. Even 100% oxygen at that pressure would provide you with only 5% of the oxygen than we normally get in each breath, so you might have trouble breathing just due to oxygen deprivation (though it's more complex than just oxygen levels since getting rid of CO₂ is part of the equation, and that gets easier at low pressure). But the pressure differential won't pop your eyes out, even if you don't take any time to acclimate to the pressure differences. People have undergone bigger absolute pressure changes than that, and even in cases where decompression sickness is fatal, it doesn't look anything like Total Recall.

Which, BTW, was a stupid movie. If you want to keep it ambiguous whether or not the situation is real or only in his head, then you only show what he directly experiences. By including scenes where he isn't present, and in fact never even learns of, the movie confirms an external reality to events. Its attempts to go back to ambiguity at the end aren't interesting, they're a cheap gimmick that the movie itself has already discounted.

 

[ben m]

You wouldn't be able to hold an oxygen mask on your face with the nearly 15 PSI differential. Surviving there without a suit would be like surviving in a balloon lofted to about 30 km altitude -- not feasible. If somehow you did, exposed skin would rapidly freeze.

Yep. The thing that matters for respiration is oxygen partial pressure. On the Earth's surface, your body gets about 2.9 psi of oxygen mixed with nitrogen and whatnot. If you're climbing Everest with an oxygen mask, you can breathe yourself about 2.9 psi of oxygen almost all by itself---with only 1 psi or so of nitrogen diluting it---so in principle you can maintain sea-level-like respiration. Reinhold Messner, climbing Everest without a gas mask, is surviving---probably just barely---on 0.8 psi of oxygen (20% of a 300 mbar atmosphere). So perhaps we can call that a lower limit.

Mars' surface pressure is about 0.1 psi, so if you were holding an ambient pressure gas mask (like scuba gear) feeding you pure oxygen, you'd be a factor of 8 short of the Everest-without-gas lower limit.

Suppose you could crank the gas mask pressure up to 0.8psi and have it (lightly) strapped onto your face. There, now you're getting as much pure oxygen as Reinhold Messner. With this setup, without a pressure suit, your lungs are holding air at a somewhat higher pressure than the outside environment---this means they want to expand, and it's hard work to exhale. Every breath you take would feel like you're blowing bubbles through a hose whose end is 1.5 feet underwater. Try it! It's not going to make your lungs pop, but it's a good amount of work on every breath.

So the answer, I think, is MAYBE JUST BARELY. If you had Reinhold Messner's red-blood-cell-count, and you're able to do a good amount of work per breath, and you have an 0.8 psi overpressure oxygen mask---yes, you'll be able to breathe on Mars without a pressure suit.

I bet that a very low-grade pressure suit----a handful of rubber straps around the chest, at the level that'd make it difficult to inhale on Earth---would take a lot of the load off of breathing. Maybe you could get up to 1.0 or 1.2 psi.

 

[phunk]

Oddly enough, yes. Volunteers had spent as much as 30 minutes with both hands in a vacuum chamber, with no worse effects than some swelling. So if your space suit had airtight cuffs, then yes you could stick your hand into dirt on Mars. Or on the Moon.

Maybe, but that dirt is unlikely to be a comfortable temperature.

 

[geni]

When the first Viking lander landed on Mars in July of 1976 The first panorama it sent back had a nice blue sky shown. That was followed about a day later by a corrected print with the pink/orange sky we've grown to love, and apologies from the imaging team for the confusion.

And thats where the conspiracy comes from. The actual issues with the colour are more complicated:

http://en.wikipedia.org/wiki/Extraterrestrial_skies#The_color_of_the_Martian_sky

 

[AdMan]

So if your space suit had airtight cuffs, then yes you could stick your hand into dirt on Mars. Or on the Moon.

Maybe, but that dirt is unlikely to be a comfortable temperature.

Or comfortable period. Lunar dust is so abrasive that it partially wore through the Apollo astronauts' gloves

 

[Mikemcc]

This is what MIT has been working on:

http://mvl.mit.edu/EVA/biosuit/index.html

I would expect that it would also need some sorted of electrical or water heating too. It seems pretty close to what Kim Stanley Robinson called 'walkers'.

Wish my professors had looked like that...

 

[dasmiller]

<supporting data snipped>
So the answer, I think, is MAYBE JUST BARELY. If you had Reinhold Messner's red-blood-cell-count, and you're able to do a good amount of work per breath, and you have an 0.8 psi overpressure oxygen mask---yes, you'll be able to breathe on Mars without a pressure suit.

You know, I'd pondered things along those lines, but you actually had facts & numbers. That's one of the coolest things I've read in a while. Thanks!

 

[I Ratant]

The instant recovery from the wild contortions and distortions on Ahnold upset me when seeing that.
Do that to anyone's face, and man, the pain and bruising and tearings of the muscles and skin would be awful, worth a few months in the hospital.

 

[Jack by the hedge]

You know, I'd pondered things along those lines, but you actually had facts & numbers. That's one of the coolest things I've read in a while. Thanks!

Seconded. It makes it seem like an intriguing possibility instead of movie fantasy.

I had just been thinking, by the way, that the transition would not necessarily be from 15 psi to near-vacuum. Whatever vessel brought you to Mars may well be built to contain a low pressure, oxygen rich atmosphere. I don't know what pressure of atmosphere spacecraft generally contain, but I'm sure I remember reading of space suits operating at about 5 psi.

 

[Ziggurat]

The instant recovery from the wild contortions and distortions on Ahnold upset me when seeing that.
Do that to anyone's face, and man, the pain and bruising and tearings of the muscles and skin would be awful, worth a few months in the hospital.

It's worse than that. Water isn't very compressible OR expandable, which means any noticeable volume changes due to pressure dropping would have to be in the form of gas bubble formation inside the body. That will tear more than just muscle and skin, that will tear blood vessels. All over the place. You'd be hemorrhaging like mad internally (including in the brain) to get that sort of effect. You wouldn't just be in a hospital for a few months, you'd be dead in a few seconds. Of course, to get that much bubble formation, you'd have to acclimatize a body to pressures FAR higher than 1 atmosphere before dropping them to near-vacuum. You'd essentially have to "carbonate" them (though not with carbon dioxide, since that would be fatal in its own right).