Author Topic: Mars Terraforming discussion  (Read 57476 times)

Offline Robotbeat

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Re: Mars Terraforming discussion
« Reply #40 on: 01/09/2014 09:41 pm »
I'm aware of absolutely no scientific finding that suggests humans need nitrogen in the air to live. Our bodies get fixed nitrogen through our diet.

I don't think it's really been researched. Yes, our bodies get nitrogen through protein, but who's to say it wouldn't get leeched out from a non-nitrogen atmosphere. We've evolved in this atmosphere, and I don't recommend living long-term in something different from this atmosphere - because otherwise, you're a human guinea pig who may end up finding out unpleasant things the hard way.

Actually I'm pretty sure it HAS been extensivly researched :) We've had people living in pure oxygen envirionments for months at a time since the 1920s IIRC. I KNOW the US and Russians researched pure O2 closed environments during the space race, at partial pressures and full pressures. The biggest downside to a pure O2 atmosphere is that pretty much everything burns unders those conditons if it gets ignited.

Randy
The last point is only really true for partial pressures higher than oxygen levels in, say, Breckenridge, Colorado.
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Offline Andrew_W

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Re: Mars Terraforming discussion
« Reply #41 on: 01/09/2014 10:32 pm »

[snip]

Sublimating the CO2 ice at the Martian poles and part of the survice CO2 ice could result in an increase from 0.6kPa to over 20kPa, most of it would be CO2, some estimates even state 30kPa ...

[snip]

Link please.

« Last Edit: 01/09/2014 10:40 pm by Andrew_W »
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Offline KelvinZero

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Re: Mars Terraforming discussion
« Reply #42 on: 01/09/2014 10:33 pm »
The last point is only really true for partial pressures higher than oxygen levels in, say, Breckenridge, Colorado.
Rats, couldn't find it.

I started a thread on this site a while ago, basically asking what the most sensible air pressure/oxygen partial pressure would be for people living away from earth.

There were some great contributions, likely as not you were on it, but I thought one of the claims was that pure oxygen increases fire risk even at low pressure. Got a reference to the contrary?

(edit: I think this is the thread, but couldnt find the quote I was thinking of)
http://forum.nasaspaceflight.com/index.php?topic=24049.0
« Last Edit: 01/10/2014 02:41 am by KelvinZero »

Offline Andrew_W

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Re: Mars Terraforming discussion
« Reply #43 on: 01/09/2014 10:53 pm »
Hop's comment on this thread?

http://forum.nasaspaceflight.com/index.php?topic=26898.msg814693#msg814693

His links not working for me.
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Offline faramund

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Re: Mars Terraforming discussion
« Reply #44 on: 01/10/2014 12:52 am »
This is a little bit OT, or at least long term. I've heard the Earth gains about 100 000t of mass each year from meteors (and also loses about 100 000t of volatiles, but anyway). Has anyone heard any equivalent figures for Mars?

I'm thinking.. if that was constant.. how long would it take for Mars to grow to a more interesting mass (say half of Earth). I'm guessing thousands of billions of years (note the if constant proviso).

Offline Robotbeat

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Re: Mars Terraforming discussion
« Reply #45 on: 01/10/2014 01:56 am »
The last point is only really true for partial pressures higher than oxygen levels in, say, Breckenridge, Colorado.
Rats, couldn't find it.

I started a thread on this site a while ago, basically asking what the most sensible air pressure/oxygen partial pressure would be for people living away from earth.

There were some great contributions, likely as not you were on it, but I thought one of the claims was that pure oxygen increases fire risk even at low pressure. Got a reference to the contrary?
i haven't seen the case made very well that the risk is significantly higher if you use an O2 partial pressure at significantly lower than Sea level.
Chris  Whoever loves correction loves knowledge, but he who hates reproof is stupid.

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Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #46 on: 01/10/2014 03:11 pm »
This is a little bit OT, or at least long term. I've heard the Earth gains about 100 000t of mass each year from meteors (and also loses about 100 000t of volatiles, but anyway). Has anyone heard any equivalent figures for Mars?
“Lunar impact rate: On average, 33 metric tons (73,000 lbs) of meteoroids hit Earth every day, the vast majority of which harmlessly ablates (“burns up”) high in the atmosphere, never making it to the ground. The moon, however, has little or no atmosphere, so meteoroids have nothing to stop them from striking the surface. ”
http://www.nasa.gov/centers/marshall/news/lunar/program_overview.html#link1
So 33 times 365 is 12,045 tons. So probably is between 10,000 and 20,000 tons per year allowing for error and normal variability. Though  in variability, I mean the small stuff. One rock hitting earth can easily exceed 100,000 tons. So the 12,045 tons is what has been observed rather allowing for 100 or 1000 year events which can so massive they bump up the "average yearly".
So for example something the size of Mars moon Deimos has hit earth over a long enough time period. Demos mass is 1.4762×10^15 kg
http://en.wikipedia.org/wiki/Deimos_%28moon%29
So 10^15 kg is 1 trillion tonnes. Or 10 million 100,000 tons.
So we don't get a Deimos size impact every 10 million years, it's more like every 100 million years, but the bigger ones would significantly increase the average yearly amount if included.
So I would say your 100,000 tones per year may be about the right amount.

It's generally thought that Mars gets about twice the impactor as Earth due to Mars location nearer the Main Asteroid belt, or Jupiter is thought to be large factor in causing a constant flow of space rocks coming into the inner planets, and Mars gets first shot at hitting them. Plus I would think that Mars elliptical orbit helps it hit a lot of them. So according to this general idea, Venus would get less impactors than Earth.
Though this generally based upon dating and counting impact craters which I wouldn't say is very precise.
Quote
I'm thinking.. if that was constant.. how long would it take for Mars to grow to a more interesting mass (say half of Earth). I'm guessing thousands of billions of years (note the if constant proviso).
Well, Mars moons could impact Mars at some point. But anyways, let's say it's 200,000 tons per year.
Mars mass is 0.64174 10^24 kg
Mass (10^24 kg) 0.64174 [Mars]   and 5.9726 [Earth]  with ratio of  Mars mass to Earth of  0.107
http://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html

So Mars is 6.4174 x 10^23 kg. Or 641,740,000 trillion tonnes.
Or 641,740,000 trillion tonnes divided by 200,000 tonnes is
3208.7 trillion years. After which it would make Mars have ratio of about .2 or 2/10th the mass of Earth.
« Last Edit: 01/10/2014 03:27 pm by gbaikie »

Offline RanulfC

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Re: Mars Terraforming discussion
« Reply #47 on: 01/10/2014 05:15 pm »
The last point is only really true for partial pressures higher than oxygen levels in, say, Breckenridge, Colorado.
Rats, couldn't find it.

I started a thread on this site a while ago, basically asking what the most sensible air pressure/oxygen partial pressure would be for people living away from earth.

There were some great contributions, likely as not you were on it, but I thought one of the claims was that pure oxygen increases fire risk even at low pressure. Got a reference to the contrary?
i haven't seen the case made very well that the risk is significantly higher if you use an O2 partial pressure at significantly lower than Sea level.
I should have been more specific yes :) I recall that Marshall Savage in The Millennial Project had quite an extensive set of references for supporting the idea of using pure O2 at partial pressures and several "experts" taking him to task for it. IIRC an experiment on the Shuttle proved him right and them wrong. As far as I know the danger DOES increase at higher pressures.

Most often I see the Apollo-1 fire cited as the main reason not to use pure O2, but rarely does anyone mention that the majority of the materials in the cabin were found to be highly flamable even in a "normal" atmosphere. I may be missremembering but I seem to recall that a full (sea-level) pressure atmosphere of pure O2 actually has to MUCH oxygen and can be dangerous?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #48 on: 01/10/2014 11:35 pm »
Quote
Regardless of what gases you add to the Martian atmosphere, a key thing for human survivability is atmospheric pressure. We need pressure suits to withstand environments with too low pressure. One of the three key metrics therefore is, whether you can get pressure high enough to allow for a non-pressurized suit environment. For humans, the key survivable limit of pressure is the Armstrong limit or 6.3kPa. At that level of pressure water boils, which kills a human being. This means the atmosphere needs to be severely thickened."

It not being able to breathe is what kills a human being. Armstrong limit is "The altitude is variously reported as being between 18,900–19,350 meters (62,000–63,500 feet, or about 12 miles (10 nmi))."
http://en.wikipedia.org/wiki/Armstrong_limit

You need pressure suit at and above about 45,000 feet:

"Above approximately 34,000 ft (10,000 m) oxygen-rich breathing mixture is required to approximate the oxygen available in the lower atmosphere, while above 40,000 ft (12,000 m) oxygen must be under positive pressure."
http://en.wikipedia.org/wiki/Pressure_suit
If breathing with positive pressure, eyeballs could be boiling but that kind of stuff is not the life threatening aspect as compared to not getting oxygen to your lungs.

Quote
Increasing pressure won't do us any good, if a 30kPa environment still involves current temperatures at Mars. The good thing is, melting the Martian CO2 ice is always related to also increasing the average temperature. It currently is 55 degrees C below 0 with large fluctuations from -150 degrees C to above 0. Fluctuations would be smoothened out by an increased CO2 atmoshpere and the overall temperature would likely increase significantly, but nowhere near Earth's average 13 degrees C.

Or if just add CO2 it freeze at the poles. Increasing pressure would increase rate CO2 deposits on Mars pole. And therefore merely adding few degrees will not change this.

Quote
The most viable method of heating up Mars I have read about are plants that put out flurine composits on Mars. Such gases, such as CFCs, have a warming factor several thousand times the one of CO2 (CF3SCF3, CF3OCF2OCF3, CF3SCF2SCF3, CF3OCF2NFCF3, C12F27N) and could over a period of decades warm up Mars significantly. We are also not talking about utopian quantities of fluorine composits, but only several times the amounts put into the Earth's atmosphere from the 70s to the early 90s (when they were banned).
There is no evidence that CFC put into Earth atmosphere, caused any amount of measurable warming.
Those consider that greenhouse gases can cause significantly amount warming, believe that the increase of amount CO2 in the atmosphere was the greenhouse gas which was mostly responsible for much warming over the last century, and such total of such warming is probably at most about .8 C.
Or CFC would caused less than .8 C warming. The amount of CFC emitted during 1970 to 1990 was about
couple tens of millions of tons. So even if put a 100 million tonnes of CFC or five times as much as done on earth, it's unlikely it cause more than 1 C increase in Mars global temperature- or not make noticeable difference.
Quote
Atmospheric composition

Even if you are able to increase average temperatures on Mars significantly and add all the CO2 ice, you end up with a somewhat cold, 30kPa 99% CO2 atmosphere. I believe the question was whether you could convert the CO2 into an O2 atmoshpere. The best way to start that is probably using some genetically manipulated live forms that use up CO2 and emit O2. But that would take quite some time. The current Marsian atmoshpere weights 25 teratons and at 30kPa it would weight above 1000 teratons. Even if 2/3rds of the Martian soil would be covered with genetically manipulated phytoplankton or other organism, that each km˛ needs to convert 10 million tons of CO2 (1000 teratons = 1000 trillion tons of CO2, 2/3rds of Mars equals 100 million km˛). Or 1m˛ of organism needs to filter 10 tons of CO2. That takes some time. A square meter of organism can only convert a few grams of CO2 per day, if not less. So we are talking hundreds, if not thousands of years.
Right. But in addition the colder atmosphere will have bad effects for anyone living on Mars. And waiting for the oxygen, is pointless for anyone spending trillions dollars terraforming.

It much better not terraforming the planet and instead one terraform a region.
And you do this with water.
So 10 meter of water depth on Earth give 1 atm of pressure. 10 meter of water on Mars give 1/3 atm.
So in swimming trucks and air mask someone out breathe 10 meter under water. Or you live in plastic bubble under 10 meters on water and keep dry.

Per ton water would cheapest think to produce on Mars other than melting frozen CO2. So it seems a 100 million tons of water would cheaper than 100 million ton of CFC.
A 100 million tons of water is 1/10th of cubic km of water. Or square km by 100 meter deep.
Since one only needs 15 meter of water depth, that's 6.6 square km at about 15 meters deep of water.
So thousands of people could live, without pressure suits in such region under water.

Offline Andrew_W

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Re: Mars Terraforming discussion
« Reply #49 on: 01/11/2014 03:29 am »
gbaikie:
Quote
Per ton water would cheapest think to produce on Mars other than melting frozen CO2. So it seems a 100 million tons of water would cheaper than 100 million ton of CFC.
A 100 million tons of water is 1/10th of cubic km of water. Or square km by 100 meter deep.
Since one only needs 15 meter of water depth, that's 6.6 square km at about 15 meters deep of water.
So thousands of people could live, without pressure suits in such region under water.

Nobody lives under water on Earth, why would it be so appealing on Mars?

I confess that in 1901 I said to my brother Orville that man would not fly for fifty years.
Wilbur Wright

Offline rockinghorse

Re: Mars Terraforming discussion
« Reply #50 on: 01/11/2014 12:29 pm »
Nobody lives under water on Earth, why would it be so appealing on Mars?

Living under water protects from radiation. It is also safer as structural failures probably do not lead into catastrophic compromise of life support.

addition: as living under water is much safer, structures can be made lighter, because they do not need to withstand large pressure differences. Therefore it is possible to construct under water larger habitats with less materials.
« Last Edit: 01/11/2014 12:55 pm by rockinghorse »

Online Mark K

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Re: Mars Terraforming discussion
« Reply #51 on: 01/11/2014 12:41 pm »
Living under water is much more difficult than living under low pressure. Even a few meters of depth leads to a lot of issues with pressure. any structural failure is much more catastrophic.

Under low pressure the pressure vessel is acting as balloon and the internal pressure can give structural support to overhead shielding. a leak and you patch and repressurize. Under water, look out. Read any of the design docs for any underwater habitats and you will see the issues with overpressure. There is a reason nobody lives underwater for any length of time.

Offline Andrew_W

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Re: Mars Terraforming discussion
« Reply #52 on: 01/11/2014 02:25 pm »
I used to be an advocate of habitable clear ice domes a few meters thick, then I discovered that, no matter how pure water is it will absorb light, especially at the red end of the spectrum, so if you're looking to use natural light at 10 or more meters down, forget it.
 On Mars melting out ice caves might be useful, but no more so than piling dirt over your habitat.
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Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #53 on: 01/11/2014 03:35 pm »
Nobody lives under water on Earth, why would it be so appealing on Mars?

Living under water protects from radiation. It is also safer as structural failures probably do not lead into catastrophic compromise of life support.

And structural factors are different on Mars vs Earth. A cubic meter of air has buoyancy force of around 1 ton
under water on Earth. On Mars it's a 1/3 ton of buoyancy. Of course all things weigh less, so the same 1 ton stone would be 1/3 ton on Mars, but the rope between them would need to be less strong. And on Mars one need to go 3 times the distance under water to get same effect from the "bends".
So structurally, a submarine goes 3 times deeper on Mars. And something like dome under water requires
less structural strength than on Earth.
So on Earth at 30 meters [98.4'] under water you at 3 atm- and Mars 1 atm.
Say have cylinder say 10 meter diameter and 5 meters tall on the bottom 30 meters deep, and going up top of cylinder is 25 meter from surface.
Let's start with steel and make it very strong and give it gives it some weight so less buoyant.
Have 1/2" steel walls and air at 3 atm.
So, it about 4 cubic meter of steel weighing 31 tons.
And displaces 392.5 cubic meter of water. Net buoyancy of 392.5  minus  31 is 361.5 tons.
So you add 361.5 tons dirt or lead or anchor to bottom which will weigh more 361.5 tons.
So dirt with density of 2 needs a bit more 2 meters deep, giving less than 3 meter height
to this very large room- 3 meter 9.8 feet. So gives more than standard 8 foot ceiling.
So if weight [ballast] it works same on Mars as Earth. If anchoring it, you need less cable strength.

Now, let's change it. Let's give it a basement. And going put structure 10 meters from the bottom and 1 meter curtain of 1/2" steel. This will be the airlock. So filled with about 1 foot of air, rest filled with water
and put hole in the middle of floor with ladder. To bottom of curtain attach 4 posts that 9 meters long and sit on bottom. So it's resting on bottom on the posts. Allowing person to exit thru bottom hole and swim somewhere. If in spacesuit, they go to surface of water on Mars. Or without spacesuit go to other "buildings" underwater.
In terms square footage this house has 844 square feet- with dirt floor or some other ballast material.

Now, we want a window. So 30 meter deep water, 10 meter from bottom and ceiling 5 meter above that
so top is 15 meter from the surface. And we need enough air pressure to stop water from coming up the hole, so that's 20 meters depth pressure. On Earth that's 2 atm. And Mars it's 1/3 of this. Or 9.8 psi.
So if want window in ceiling it has to withstand the difference of pressure of the 5 meter plus 1 foot
water depth pressure.
Earth is 14.7 psi per 10 meter and on Mars it is 1/3 of this. And 5 meter is half of that. So around 2 1/2 psi.
Office building on Earth have deal with about 2 psi. So glass has to be a bit stronger than glass used
on office buildings on Earth. So if dome shape and one probably make it out plastic this would not require very thick material. And could replace this cylinder shape for hemisphere dome. So keep metal floor and replace the rest with a dome. But make easier to transport from Earth it can be sectional rather one solid piece.
And could constructed under water- so without spacesuits. So, it has metal frame which adds structural strength, and the panels don't have to be very strong- depending on how big the panes are.

So you living in something that looks like a greenhouse underwater. Same thing could be done on Earth, but it requires 3 times the structural strength. Of course if smaller it has less buoyancy and does not require as much strength.
Oh, to give more usable room, the dome could put on top of say 1 or 2 meter high cylinder wall. And also dome shape is less total volume as compared to the cylinder shape [less buoyancy].
And this can extended to actual greenhouses to grow plants. And generally it's thought plants don't need as much pressure as humans need so plant greenhouse could be bit closer to surface of water.
And consistency of water temperature will make growing plants easier/safer. You also don't need 8 foot high ceiling, 4 foot would work. 

Edit: in terms of radiation, the above would same levels as on Earth. You might not be able to get a sun tan, though you can use tanning lights.
 
« Last Edit: 01/11/2014 03:57 pm by gbaikie »

Offline RonM

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Re: Mars Terraforming discussion
« Reply #54 on: 01/11/2014 03:54 pm »
The underwater scenario isn't worth the effort. It adds complexity without any real benefit. When you leave your frozen over lake, you would still need a spacesuit to explore and use the rest of Mars. It would be simpler and cheaper to colonize Mars as is.

The key is to raise the atmospheric pressure of the planet.

Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #55 on: 01/11/2014 04:13 pm »
gbaikie:
Quote
Per ton water would cheapest think to produce on Mars other than melting frozen CO2. So it seems a 100 million tons of water would cheaper than 100 million ton of CFC.
A 100 million tons of water is 1/10th of cubic km of water. Or square km by 100 meter deep.
Since one only needs 15 meter of water depth, that's 6.6 square km at about 15 meters deep of water.
So thousands of people could live, without pressure suits in such region under water.

Nobody lives under water on Earth, why would it be so appealing on Mars?

No one living under water, yet. It's still the beginning of 21 century. But you go to restaurant underwater:
http://conradhotels3.hilton.com/en/hotels/maldives/conrad-maldives-rangali-island-MLEHICI/index.html

Main problem, I would say are transportation issues.

Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #56 on: 01/11/2014 04:37 pm »
I used to be an advocate of habitable clear ice domes a few meters thick, then I discovered that, no matter how pure water is it will absorb light, especially at the red end of the spectrum, so if you're looking to use natural light at 10 or more meters down, forget it.
 On Mars melting out ice caves might be useful, but no more so than piling dirt over your habitat.

You lose a lot of red light below 10 meters. And red portion of sunlight is a substantial amount of wavelength of the solar flux. Or wiki says:
"With increasing depth underwater, sunlight is absorbed, and the amount of visible light diminishes. Because absorption is greater for long wavelengths (red end of the visible spectrum) than for short wavelengths (blue end of the visible spectrum), the colour spectrum is rapidly altered with increasing depth. White objects at the surface appear bluish underwater, and red objects appear dark, even black. Although light penetration will be less if water is turbid, in the very clear water of the open ocean less than 25% of the surface light reaches a depth of 10 m (33 feet)."
http://en.wikipedia.org/wiki/Underwater

But keep in mind the clouds block a lot light on Earth.
120,000 lux    Brightest sunlight
1,000 - 2,000 lux    Typical overcast day, midday
http://en.wikipedia.org/wiki/Daylight
So those poor people who live in Seattle, most of time only get about 1% of the sunlight.
And if want red light, it's not beyond our capability to make red light.

One relevant question, if 75 % of the sunlight doesn't reach 10 meter, where does that energy
actually go?
« Last Edit: 01/11/2014 05:37 pm by gbaikie »

Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #57 on: 01/11/2014 05:14 pm »
As to a question.
Wiki:
"A solar pond is simply a pool of saltwater which collects and stores solar thermal energy. The saltwater naturally forms a vertical salinity gradient also known as a "halocline", in which low-salinity water floats on top of high-salinity water. The layers of salt solutions increase in concentration (and therefore density) with depth. Below a certain depth, the solution has a uniformly high salt concentration.

There are 3 distinct layers of water in the pond:

    The top layer, which has a low salt content.
    An intermediate insulating layer with a salt gradient, which establishes a density gradient that prevents heat exchange by natural convection.
    The bottom layer, which has a high salt content."
And:
"The temperature gradient alone causes a density gradient that decreases with depth. However the salinity gradient forms a density gradient that increases with depth, and this counteracts the temperature gradient, thus preventing heat in the lower layers from moving upwards by convection and leaving the pond. This means that the temperature at the bottom of the pond will rise to over 90 °C"
http://en.wikipedia.org/wiki/Solar_pond

Now what does 90 C do to an egg?
90 C equals 194 F
To fry eggs on a sidewalk the magical number is 158 F.  And people have problems trying to see if they
can fry eggs on a sidewalk. It's sometimes called myth that one could ever "really" do this.

Say at 12,000 feet. What is boiling point of water?
Answer:
12,000' (3657.6m)    189.8°F (87.6°C)
Do you think you could boil an egg if at 12,000 feet, without a pressure cooker?
A pressure cooker would be a faster way to boil an egg, but question is could
get a hard boiled egg, without pressure cooker at 12,000 ft?
People going to Mars probably should be familiar with pressure cooker if
they want boil food in water. So like if they want spaghetti or boiled eggs.
So pressure at 12,000 feet is about 9.3 psi
Anyways it seems to me you can boil an egg at 90 C, but not sure about a potato:
" as described in Charles Darwin's The Voyage of the Beagle (chapter XV, March 21st, 1835 books.google):

    Having crossed the Peuquenes [Piuquenes], we descended into a mountainous country, intermediate between the two main ranges, and then took up our quarters for the night. We were now in the republic of Mendoza. The elevation was probably not under 11,000 feet [...]. At the place where we slept water necessarily boiled, from the diminished pressure of the atmosphere, at a lower temperature than it does in a less lofty country; the case being the converse of that of a Papin's digester. Hence the potatoes, after remaining for some hours in the boiling water, were nearly as hard as ever. The pot was left on the fire all night, and next morning it was boiled again, but yet the potatoes were not cooked."
http://en.wikipedia.org/wiki/High-altitude_cooking
« Last Edit: 01/11/2014 05:31 pm by gbaikie »

Offline KelvinZero

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Re: Mars Terraforming discussion
« Reply #58 on: 01/11/2014 10:41 pm »
Living under water is much more difficult than living under low pressure. Even a few meters of depth leads to a lot of issues with pressure. any structural failure is much more catastrophic.

Under low pressure the pressure vessel is acting as balloon and the internal pressure can give structural support to overhead shielding. a leak and you patch and repressurize. Under water, look out. Read any of the design docs for any underwater habitats and you will see the issues with overpressure. There is a reason nobody lives underwater for any length of time.

But on Mars, under 30 meters of water you would be earth sealevel pressure. A bubble probably is no good for long term survival, you probably need tens of meters of material to stop the cosmic rays, though some people suggest the risks of low level radiation have been greatly overestimated.

This idea is a favorite of mine:
http://forum.nasaspaceflight.com/index.php?topic=26678.0
I mention going kilometers down, but ignore that. Consider it just an example for the maths. Here is a more practical example:
http://forum.nasaspaceflight.com/index.php?topic=33069.msg1109011#msg1109011

It has big advantages and some obvious disadvantages. IMO it has enough advantages that if you can't think of exploiting the principle in some way you are just not trying, but of course it doesnt solve everything. It's not an end-to-end solution.




« Last Edit: 01/11/2014 10:51 pm by KelvinZero »

Offline gbaikie

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Re: Mars Terraforming discussion
« Reply #59 on: 01/12/2014 01:29 am »
The problem with any kind of terraforming is costs.
To colonize Mars one needs water to be low cost.

Edit: There is a similar requirement for the Moon.
With Moon one has to be able to make rocket fuel cheap enough
so it's cheaper to make rocket on the Moon than cost of shipping
it from Earth. Otherwise little value to explore or go to Moon.
Likewise, for Mars settlement one needs water to be low cost.

So NASA should explore the Moon to determine whether there minable lunar water.
And NASA should explore Mars to determine whether living on Mars can be affordable.
Which is largely to do with being able to get usable water at a low cost.

So have low cost of having dwellings on Mars, low cost of producing food, low cost
transportation to and from Mars, and low cost of Mars water.
For staying for more than decade on Mars- cost of water will most important.
Farming requires a lot of water. Human living in city consume a lot of water,
but the food they eat requires water. Or expensive water, no farming.
If one has access to low cost water, on Earth, and you will get farming in most
areas.
So Mars is significant because it's a place one could farm. And the US is a superpower
because it is a place to farm. The US is obviously doing more things than farming, but
farming is necessary aspect. And having cheap water in US is necessary aspect of
whether there is farming or not.

So to start the ball going, the Moon requires that you make cheap rocket fuel.
And for Mars it require cheap water- not necessarily water to make rocket fuel.
But rather water which is not poisonous to life is required for humans and plants and
other animals. So, cheap non-poisonous water is needed on Mars
With the Moon water could be highly posionous- it does not matter that much-
as it's mostly about rocket fuel.

So once one develops market for Lunar rocket fuel, eventually this will lead
to lower cost of the water used to make rocket fuel. So lunar water
could start at $500 per lb, and within couple decades lower to $100 per lb
or less. Or if there is trillion lbs of water minable on the moon, one should
not think that if it starts at $500 per lb, that there is 500 trillion dollars of water
on the Moon. It's more like 1 trillion dollars of water.  Meaning by time
1/2 trillion lbs could be mined, lunar water could likely around $1 per lb,
and this might take over a century to get to this point. Or it may never
be mined because by that time, water could mined cheaper elsewhere
and imported to the Moon.
With Mars for there to be settlements water could be as high as $500 per lb,
but likewise the costs will lower over time. And it seems with Mars, one will
get to a point sooner of water being less than $1 per lb, as compared the the Moon.

Because cost of Mars water would be critical to Mars. Or a lot water is needed.
And if we assume water is available to harvest, then this will drive water to a
lower price.
Or on the Moon there may be demand for thousands of tons of
water per year, with people living on Mars, the demand could millions of tons
of water- if cheap enough per ton.
Or 50 years after lunar mining begins, you might see a swimming pools on the
Moon, on Mars over same time period after the beginning of settlements,
you might see lakes of water.

[So snipped the rest of my post and put it another thread post:
http://forum.nasaspaceflight.com/index.php?topic=33104.msg1119603#msg1119603 ]
« Last Edit: 01/12/2014 02:44 pm by gbaikie »

Tags: Chemistry