Minimum Terraformation - When can we ditch the pressure suits?

Ian Flint · 2003-11-25 11:24:52

I'm sure someone has answered this somewhere but I can't find it.

What is the minimum atmospheric pressure the human body can withstand?

How long would it take to get Mars' pressure up to that level?

~Eternal~ · 2003-11-25 16:21:24

Ehh I'm not for sure but I think its 100-300 mb :b.
And I say with Release of locked Nitrogen, CO2 Import and PFC release, and Other terraformation efforts, 40-60 years.

Rxke · 2003-11-26 09:32:35

There's just a lot of calculating going on in the 'rapid terraforming' thread about these questions.

Interesting read. Esp. RobertDyck's comments on page 5, Nov. 25 2003, 14:37; where he discusses the minimal pressures needed in order to keep our lungs functioning.

mbastion · 2004-05-31 01:14:19

Hi,

If we can't walk around naked afterwards (assuming you'd want to) then it's not terraforming. Terraforming is making a planet like earth, not making a planet habitable in presure-suits.

http://www.geocities.com/alt_cosmos/ind … index.html

Michael

karov · 2004-06-03 07:47:47

We can not walk around naked almost nowhere here on Earth, too. We need clothes, sun glasses... and other uncountablee means of phenotype augmentation. I understand you dogmatical attitude towards the term "terraforming", but considering the vast spectrum of very hostile environments even here on the mother/home planet, we have to allow much broader deffinition of terraforming. For example such, generalised to cover any environment production or modification allowing full-life cycle habitation by standart human biological unit, even less. The canonical full-scale "geological terraforming" is unachievable ideal even here on Earth -- it was and comperativelly soon shall be practically uninhabitable by the present "human condition" units. If we blindly stick on the terms that will lead to functional taboo on using the term "terraforming" or/and to endless unusefull coinage of pseudo-greco/latin terms. Let say that the "terraforming" is just an ONE WORD slang for modifing or constructing an environment towards full or partial human compatibility. The descriptive term in that light should be "standart human life supporting artificial ecology construction".

About the human breathable-floid presure endurance limits:
For breathing gasses the lowest level is the boiling point of body tissue water -- it evaporates at human body temperature of 36-37 degrees centigrade at 0.07 Athmospheres ( but at least 0.15 Atm of oxigen presure are necesarry for breathing, so this is the lower limit); the upper is 80-100 Atm. for hydrogen mixture with traces of oxigen (no smoking!!! - although the mixture is not explosive); even bigger for liquid breathing -- water, fluorides...

World water ocean saturated replenishingly with enough oxigen concentration for human liquid breathing is "terraformed", isn`t it?

Or high-mountain environment with one sixth of the sea level presure of pure oxigen?

Dook · 2004-06-03 08:27:00

Ehh I'm not for sure but I think its 100-300 mb :b.
And I say with Release of locked Nitrogen, CO2 Import and PFC release, and Other terraformation efforts, 40-60 years.

Where did you come across a reference that says there is nitrogen locked in the soil of mars?

Shaun Barrett · 2004-06-03 21:22:49

Yes, Dook. A good question concerning the availability of nitrogen on Mars.
Over at "Water, not CO2", here in Acheron Labs, I have been involved in a critique of new member MB's assessment of the 'terraformability' of Mars. If he had waded into the argument with expressions of doubt about whether Mars has sufficient nitrogen ever to be truly terraformed, I think he would have had a much better case.
To me, the lack of a handy 150 to 300 millibars of accessible nitrogen in the martian volatile inventory is the most obvious impediment to making Mars truly Earth-like (i.e. producing a practical and breathable atmosphere).

This leads on to the question of the minimum pressure needed by the human body, which I think Karov has answered very well. (A warm welcome to you, Karov, by the way! )

The question of how much pressure is required to prevent the water in a human body boiling away has been addressed here at New Mars before. I don't remember now exactly what figures were cited but Karov's estimate of 0.07 Atmospheres (~ 70 millibars) seems about right. Then there's the bare minimum physiological requirement of 0.15 Atmospheres (~ 150 millibars) of oxygen partial pressure, Karov mentions.
Robert Dyck, who has graced these pages with numerous intelligent and highly informative posts, brought the problem of dehydration at low atmospheric pressure to our attention elsewhere at New Mars.
This suggests that, although you could breathe a pure oxygen atmosphere at 150 millibars of pressure (just! ), and although your bodily fluids wouldn't explosively boil away, your eyes and lungs would quickly dry out and become extremely uncomfortable.

O.K. So what about a 350 millibar pure O2 atmosphere for Mars? (I know it isn't strictly what this thread was started for but it's in the same ballpark and I think it's a pertinent corollary to the main point.) In the absence of appreciable amounts of nitrogen, or another suitable 'mixer' gas, this may be the best we could achieve on Mars if we wanted a breathable atmosphere. But, as we've discussed in the past, there may be spontaneous combustion problems.

What I'm trying to say here is that asking what the minimum survivable ambient pressure might be for an unprotected human is a question of only academic interest. There are other parameters which cannot be ignored if you want to design a practical atmosphere.

Without being at all sure of the consequences for plant-life and various other potential problems, I think an atmosphere with 200mb of O2 and 150mb of N2 (350mb in total) may prove to be the practical minimum - with appropriate low levels of CO2, of course.
An ideal atmosphere for Mars might be 500 millibars, with partial pressures of 200mb O2 and 300mb N2.

But that brings us back to the question about nitrogen availability again!
???

mbastion · 2004-06-04 01:23:51

Hi,

>Let say that the "terraforming" is just an ONE WORD slang for
>modifing or constructing an environment towards full or partial
>human compatibility.

No thanx. That's not what it means.

Michael
http://www.geocities.com/alt_cosmos/ind … index.html

karov · 2004-06-04 08:59:36

mbastion,

The resistence is futile!
Give up!
Accept the notion of "terraforming" as understood by all the others in this forum and abroad.
The semantics belong to the realm of the internal subjective human cosmos, which also possesses deep imanent infinities, the same way the outer objective one.
Don`t try to set artificial limits on discourse, which leads you in unending regress of the word-flood.
Every word means what the people agree to put in it.
The language is conventional.
Like mathematics it doesn`t have proof for existence out of its own realm.

If you don`t agree this as usual, post a vote and you`ll see the results.

MarsDog · 2004-06-04 12:19:51

Even the Earth is far from ideal and conditions evolve that could end life. For geologically short periods we will be able to create habitable places elsewhere. The guesswork is enjoyable and mbastion's objections need to be examined further.

karov · 2004-06-04 15:22:32

Yes. I do not agree with the semantics juggling of mbastion, but it is scientifically mandatory every objective to be checked, the same way as every argument pro terraforming feasibility.

Generally, on the topic of the thread about 'minimum terraformation': the minimums of habitability depend entirelly on the parameters of endurance of human body in different environments. They practically are far narrow over the overall field between the extremes -- temperature, pressure, gravity, atmosphere content... Partial terraforming could mean not direct livability of the environment but just permiting lighter body protection: masks, etc.

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#1 2003-11-25 11:24:52

Re: Minimum Terraformation - When can we ditch the pressure suits?

#2 2003-11-25 16:21:24

Re: Minimum Terraformation - When can we ditch the pressure suits?

#3 2003-11-26 09:32:35

Re: Minimum Terraformation - When can we ditch the pressure suits?

#4 2004-05-31 01:14:19

Re: Minimum Terraformation - When can we ditch the pressure suits?

#5 2004-06-03 07:47:47

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#6 2004-06-03 08:27:00

Re: Minimum Terraformation - When can we ditch the pressure suits?

#7 2004-06-03 21:22:49

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#8 2004-06-04 01:23:51

Re: Minimum Terraformation - When can we ditch the pressure suits?

#9 2004-06-04 08:59:36

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#10 2004-06-04 12:19:51

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