Pack for a day trip to mars!

[Geronimo]

Originally posted by Spiffor
Low pressure can have important reverse effects for people, even ones that are very well acclimated. Professional alpinists can't stay long at the summit of mount Everest, despite their oxygen and water reserves, because of the ill effects of pressure alone. And pressure at the Everest Summit is ca 33% of the one at sea level. Mars's pressure is 1%

it aint healthy certainly, but it kills you very slowly.

[The Mad Monk]

...and Mars will kill you less slowly.

[Geronimo]

Originally posted by The Mad Monk
...and Mars will kill you less slowly.

it might take a few hours if you prepare properly. AFAIK nobody in good health has died on everest exclusively from pressure effects from just a few hours exposure. Mars may have an average pressure 30 times lower than everest but it can be quite a bit warmer. I guess the main issue would be whether or not it would be possible to breath oxygen delivered at the minimum necessary partial pressure needed for gas exchange to function properly in the lungs under the highest possible atmospheric pressure found on mars and I suspect it might not be. In any case Mars's low pressure and indeed the vacuum of space are not the ultra lethal effcient killers they are made out to be. The degree of lethality of very low ambient pressure is vastly overstated by most people.

[Spiffor]

Originally posted by Geronimo
it aint healthy certainly, but it kills you very slowly.

Yep, but we're talking about a day trip here. It's true one may survive for a few seconds (probably even one or two minutes) in Mars with minimum equipment - but I don't think a minimal equipment makes much difference in comparison with going there naked.

With excellent equipment that cares for all problems but pressure (oxygen reserves, water, heat), and an excellent training, the day-traveller to Mars would still need acclimataion to 1 kPa pressure if he wanted to last more than a few minutes.

And considering that even the best trained humans cannot last very long in a 30 kPa environment, I don't see how the day-traveller to Mars would sustain the several hours of acclimatation that are required to reach 1 kPa.

(Mars' pressure is equivalent to Earth pressure at 35,000 m of altitude - it is recommanded to climb less than 1m/second to acclimate. The acclimatation would then last more than 9 hours and a half)

[Blake]

Actually landing at a low altitude spot is a good point. Find a, ah, mohole, i think thats a good as word as any, a natural shaft, hole or crevice deep into Mars crusts, on Mars theres no water action to fill them in so they could easily exist. The pressure at the bottom would be a bit higher, and if deep enough, there would even be some heat from Mars core. Pack a torch.

But you don't want to go to mars and spend all the time in the deepest hole you can find. A better idea might be a big transparent plastic bubble, it could be reinforced with chain mesh (on the outside of the bubble) to help withstand the pressure and protect against pointy rocks. To get in and out a strong circular steel trapdoor would suffice, with a good seal designed for low pressure and extreme cold, it should open inwards so air pressure will keep it firmly sealed when you go for a roll on the martian surface.

I'm sure you can't get a chain mesh reinforced plastic bubble off the shelf (as not many civilians need equipment designed for low pressure enviroments, altough the trapdoor would be standard pressure/vacuum chamber/submarine stuff as used scientists), but you could get one made to order, and rolling around the surface of mars in a big bubble would be well worth it.

I also believe the pressure on Mars is high enough that you only need a sealed, airtight helmet for breathing, for the rest of your body a skin-tight reinforced fabric suit would do the trick (as in, theres very little air trapped between your body and the suit), you'd need heating tho. The combination of getting a strong enough fabric, heating for the entire body including gloves, flexible enough to still be mobile and precision made to fit your form probably puts this outside the scope of civilians.

edit: I didn't read the part about walking on Mars. But you can walk in the bubble making the bubble roll so you could travel around the surface at a pretty good pace. And the bubble would be way more comfortable than a suit. And besides the topology of a pressure suit is identical to that of a bubble.

[Geronimo]

Originally posted by Spiffor

Yep, but we're talking about a day trip here. It's true one may survive for a few seconds (probably even one or two minutes) in Mars with minimum equipment - but I don't think a minimal equipment makes much difference in comparison with going there naked.

With excellent equipment that cares for all problems but pressure (oxygen reserves, water, heat), and an excellent training, the day-traveller to Mars would still need acclimataion to 1 kPa pressure if he wanted to last more than a few minutes.

And considering that even the best trained humans cannot last very long in a 30 kPa environment, I don't see how the day-traveller to Mars would sustain the several hours of acclimatation that are required to reach 1 kPa.

(Mars' pressure is equivalent to Earth pressure at 35,000 m of altitude - it is recommanded to climb less than 1m/second to acclimate. The acclimatation would then last more than 9 hours and a half)

from the USAF's flight surgeon guide I guess I would have to agree. It suggests that it is impossible to function without a pressure suit even with pressurized oxygen available when ambient pressure drops below 47 mm Hg. So much for the bubble free day trip, unless there are times in the deepest valley on mars when the pressure reaches 47 times average ambient pressure which I can't imagine ever occuring.

Oh well, the important thing I want people to understand is that exposure to low pressure or even vacuum is a fairly inefficient way to get killed, especially compared to popular misconceptions of boiling blood, bursting eyeballs and similar assorted nonsense.

[Spiffor]

BTW, since Mars is extremely dry, you'd need a good water supply. A good ol' solid gourd should be enough to store water at its usual pressure. But since the pressure in the gourd and the external pressure are completely different, I'd imagine the water would splash upon opening, like a shaken bottle of coke.

Edit: or for a better comparison, like a high-pressure cleaner: the pressure of the water in these things is 100 times the atmospheric pressure on earth.

[Spiffor]

Originally posted by Geronimo
from the USAF's flight surgeon guide I guess I would have to agree. It suggests that it is impossible to function without a pressure suit even with pressurized oxygen available when ambient pressure drops below 47 mm Hg. So much for the bubble free day trip, unless there are times in the deepest valley on mars when the pressure reaches 47 times average ambient pressure which I can't imagine ever occuring.

Well, 47 mm Hg is only about 6 times superior to Mars' normal pressure IIUC (1 kPa = 7,6 mm Hg). So it's not completely out of the imaginary to find such a pressure on Mars. But then, the place is likely to be quite shady, and thus cold

[Dr Strangelove]

Could you use the high altitude flight suits used by the pilots of the U-2 and SR-7? IIRC the SR-7 often cruised at 100,000 feet. Does anyone know the atmospheric pressure at that altitude?

[Spiffor]

Originally posted by Dr Strangelove
Could you use the high altitude flight suits used by the pilots of the U-2 and SR-7? IIRC the SR-7 often cruised at 100,000 feet. Does anyone know the atmospheric pressure at that altitude?

Similar to Mars, from what I read.

[MikeH]

No spacesuits? I'd have a submarine to live in.

[Pax]

The answer seems to be a pressure suit or a mechanical pressure suit that is heated. Some pressure suits are available for commericial purchase. These probably won't be able to withstand the requirements of mars but heated pressure suits sound cheaper than the current space suits. The price of a single space suit is about 1-2 million dollars. If you could make a pressure suit that would do the job for 100,000 that would be significantly better.

Methods for heating could be filaments, heated liquid running through a system through the suit, or anything.

My second question is could we make a habitat for the day traveller to sleep in so that he can extend his stay. Once again using items that are commercially available or at least relatively cheap.

[KrazyHorse]

Originally posted by Spiffor
If you often scuba-dive, I take it you have the habit of stopping your swim-up at regular intervals (so that your lungs can progressively adapt to the new, lower pressure without exploding).
The differences of pressure between deep water and surface are enough to kill you if you don't go progressively enough. And yet, the difference of pressure is faaar inferior to the difference between Earth and Mars. If you get out of a pressurized vehicle and were confront to Mars's tiny pressure, you'd die as surely as if you swam up from the most extremes depths of sea to the durface in one second.

If you don't wish to play the bubble-man on Mars, maybe the "outside the box" possibility would be to use your monthes-long trip to progressively adapt the cabin pressure to 1 kPa (Mars's pressure). But I absolutely don't know if the human body could live under this pressure at all, regardless of the transition time.

Spiffor, do you mind explaining to me how you're going to breathe when the partial pressure of oxygen is 1kPa?

[KrazyHorse]

Originally posted by Pax
I'm disappointed in the inability of most of you to think outside the box. I guess it's too easy to be negative.

It's easy to be right, actually.

"Thinking outside the box" indeed.

It might be possible, as Dan said, to wear a skintight suit which would, by its elasticity, provide sufficient, even pressure across the entire body. No such suit exists, AFAIK. The technical requirements to fit such a suit exactly and to have it provide even pressure under large expansions (such as breathing) are far greater than those required for a simple pressurised suit.

[Spiffor]

Originally posted by KrazyHorse
Spiffor, do you mind explaining to me how you're going to breathe when the partial pressure of oxygen is 1kPa?

I can't. When I wrote it, I still hadn't read about the pressure requirements of respiration, which is why I didn't know if such a low pressure was viable for a human body at all, even with acclimatation time.