Terraform Moon With Earths Excess Co2

[CaptainPanic]

yes, but that doesn't matter.

 

to have liquid water be a possibility you need certain conditions. the bare minimum conditions for liquid water are its triple point which is 0*C and 611Pa

 

so you need that sort of pressure before liquid water is possible.

 

Ok... time for thermodynamics.

I seem to be the only one who disagrees with some basic principles here, so correct me if you feel I'm wrong.

 

Main question:

Why would the CO2 pressure be of ANY relevance at all for water?

 

As insane_alien points out, the triple point of water is 0*C and 611Pa... but that's 611 Pa of WATER vapor pressure... not total pressure. Evaporation is related to the PARTIAL pressure of that particular component in the gas phase, not the total pressure. You can put 3 atmosphere of CO2 on a flask, and the triple point of water will not change... At 0 deg C, it will still evaporate until the partial pressure of water reaches 611 Pa.

 

The total pressure only influences whether the water will just evaporate normally, or boil. If the total pressure is lower than the vapor pressure, the liquid will boil. If the total pressure is higher than the water pressure, the liquid will just evaporate until the vapor pressure is reached.

 

http://en.wikipedia.org/wiki/Vapour_pressure_of_water#Table_of_Water_Vapour_Pressures

[Moontanman]

Ok... time for thermodynamics.

I seem to be the only one who disagrees with some basic principles here, so correct me if you feel I'm wrong.

 

Main question:

Why would the CO2 pressure be of ANY relevance at all for water?

 

As insane_alien points out, the triple point of water is 0*C and 611Pa... but that's 611 Pa of WATER vapor pressure... not total pressure. Evaporation is related to the PARTIAL pressure of that particular component in the gas phase, not the total pressure. You can put 3 atmosphere of CO2 on a flask, and the triple point of water will not change... At 0 deg C, it will still evaporate until the partial pressure of water reaches 611 Pa.

 

The total pressure only influences whether the water will just evaporate normally, or boil. If the total pressure is lower than the vapor pressure, the liquid will boil. If the total pressure is higher than the water pressure, the liquid will just evaporate until the vapor pressure is reached.

 

http://en.wikipedia.org/wiki/Vapour_pressure_of_water#Table_of_Water_Vapour_Pressures

 

 

CO2 pressure is relevant for water because the moon has no atmosphere, on the moon water cannot be a liquid, it is either frozen or a gas. if you are adding an atmosphere (in this case we are proposing an atmosphere of CO2 removed from the earth) unless the pressure of this CO2 atmosphere is high enough water will still not be able to be a liquid at the temps on the surface of the moon. The trillion tons of CO2 is not enough to raise the gas pressure on the moon to a point where water could be a liquid at the temps on the moon.

[CaptainPanic]

CO2 pressure is relevant for water because the moon has no atmosphere, on the moon water cannot be a liquid, it is either frozen or a gas. if you are adding an atmosphere (in this case we are proposing an atmosphere of CO2 removed from the earth) unless the pressure of this CO2 atmosphere is high enough water will still not be able to be a liquid at the temps on the surface of the moon. The trillion tons of CO2 is not enough to raise the gas pressure on the moon to a point where water could be a liquid at the temps on the moon.

And I maintain that this is not true.

 

You can only have liquid water if your system fulfills two criteria:

1. Temperature is above zero degrees Celsius (but below the critical temperature of water)

2. The partial pressure of water in the gas phase is at its vapor pressure

 

If you fail point 1 (temperature is below zero degrees Celsius) then water can only exist in solid and vapor.

If you fail point 2 (partial pressure of water is below its vapor pressure) then regardless of the state of water (liquid or solid), it will evaporate (or sublimate).

 

The only alternative is the earth situation, which is never in equilibrium, but in a cycle. The partial pressure of water is often below its vapor pressure, which means that water constantly evaporates. But, in other locations (namely high up in the clouds) the partial pressure reaches or even exceeds the vapor pressure, so you get condensation. If the temperature is below zero, this same phenomenon occurs, but now you get ice (directly) from vapor.

 

On earth, you could theoretically remove all nitrogen and oxygen, and we would still have the ice caps at the poles. We would still have our oceans. Water would still evaporate, and condensate. Only difference is probably that phenomena like wind would be different... and clouds would have buoyancy problems... but that is a completely different topic than what we discuss (don't use it to hijack this thread).

 

In summary, I maintain that CO2 is completely irrelevant to the presence of liquid water on the moon.

[insane_alien]

Evaporation is related to the PARTIAL pressure of that particular component in the gas phase, not the total pressure. You can put 3 atmosphere of CO2 on a flask, and the triple point of water will not change... At 0 deg C, it will still evaporate until the partial pressure of water reaches 611 Pa.

 

The total pressure only influences whether the water will just evaporate normally, or boil. If the total pressure is lower than the vapor pressure, the liquid will boil. If the total pressure is higher than the water pressure, the liquid will just evaporate until the vapor pressure is reached.

 

http://en.wikipedia.org/wiki/Vapour_pressure_of_water#Table_of_Water_Vapour_Pressures

 

quite true. BUT the presence of the CO2 DOES change a few things. If the system is a vacuum, the evapouration of the water is going to be heat limited, as in it'll evapourate however fast it can extract heat out the system which will be high.

 

with the atmosphere of CO2, assuming there isn't much movement of the atmosphere, is going to be diffusion limited instead. which will be much slower.

 

case and point, if you put a beaker of liquid water into a compartment filled with dry nitrogen with zero humidity, the water will not flash boil. if you put it into a vacuum, it will flash boil.

 

it is still going to evapourate i have no problem accepting that, but the point is, it will exist for more than a breif period.

Edited December 30, 2010 by insane_alien

[Cyclonebuster]

quite true. BUT the presence of the CO2 DOES change a few things. If the system is a vacuum, the evapouration of the water is going to be heat limited, as in it'll evapourate however fast it can extract heat out the system which will be high.

 

with the atmosphere of CO2, assuming there isn't much movement of the atmosphere, is going to be diffusion limited instead. which will be much slower.

 

case and point, if you put a beaker of liquid water into a compartment filled with dry nitrogen with zero humidity, the water will not flash boil. if you put it into a vacuum, it will flash boil.

 

it is still going to evapourate i have no problem accepting that, but the point is, it will exist for more than a breif period.

 

Since it is more heavy than water won't it stay on the moon longer than water? We already know water exists on the moon.

[Moontanman]

Since it is more heavy than water won't it stay on the moon longer than water? We already know water exists on the moon.

 

Yes water exists on the moon, in the form of ice inside craters that are in perpetual shadow. No liquid water can exist on the moon. Further more the temps on the moon, due to the long day night cycle, are so extreme that the idea of very low pressure liquid water would still not work. Day temps can rise above the boiling point of water at the pressure of the Earth surface and night time temps dip far below zero. it would take more than the minimum pressure to insure liquid water on the moon. The "trillion" tons of CO2 would not provide enough pressure for water to exist as a liquid on the moon...

[CaptainPanic]

Yes water exists on the moon, in the form of ice inside craters that are in perpetual shadow. No liquid water can exist on the moon. Further more the temps on the moon, due to the long day night cycle, are so extreme that the idea of very low pressure liquid water would still not work. Day temps can rise above the boiling point of water at the pressure of the Earth surface and night time temps dip far below zero. it would take more than the minimum pressure to insure liquid water on the moon. The "trillion" tons of CO2 would not provide enough pressure for water to exist as a liquid on the moon...

Have you even read what I wrote earlier?

 

Why do you persist that the CO2 pressure is so relevant? The only difference that it will make is that with CO2 pressure, water will merely evaporate, and without CO2 it will boil. But in both cases, regardless of whether it's liquid or solid, it will keep evaporating/sublimating until the partial gas pressure of water is equal to the vapor pressure at the temperature of the liquid/solid water. For this discussion, it is very important that you understand this.

 

The only reason that ice exists on the moon is that it's so damned cold in those craters that it only evaporates really (really!) slowly.

[Cyclonebuster]

Have you even read what I wrote earlier?

 

Why do you persist that the CO2 pressure is so relevant? The only difference that it will make is that with CO2 pressure, water will merely evaporate, and without CO2 it will boil. But in both cases, regardless of whether it's liquid or solid, it will keep evaporating/sublimating until the partial gas pressure of water is equal to the vapor pressure at the temperature of the liquid/solid water. For this discussion, it is very important that you understand this.

 

The only reason that ice exists on the moon is that it's so damned cold in those craters that it only evaporates really (really!) slowly.

 

 

 

 

Like over a million years?

[insane_alien]

Why do you persist that the CO2 pressure is so relevant?

 

It is important. the question was, how much would it take for liquid water to exist on the surface of the moon, timescales weren't included for one

 

and an atmosphere adds a lot of resistance so the local partial pressure of water COULD reach equilibrium locally.

 

i'd also like to point out that there are few places on earth where the relative humidity is 100% yet bodies of liquid water exist in these areas.

[Cyclonebuster]

It is important. the question was, how much would it take for liquid water to exist on the surface of the moon, timescales weren't included for one

 

and an atmosphere adds a lot of resistance so the local partial pressure of water COULD reach equilibrium locally.

 

i'd also like to point out that there are few places on earth where the relative humidity is 100% yet bodies of liquid water exist in these areas.

 

Really really slowly means over a million years right? It does that faster on Earth doesn't it?

Edited January 1, 2011 by Cyclonebuster

[Mr Skeptic]

It is important. the question was, how much would it take for liquid water to exist on the surface of the moon, timescales weren't included for one

t bodies of liquid water exist in these areas.

 

In that case, couldn't we do that now, using rapid enough heating that the boiling water will provide enough pressure to keep the rest from boiling, at least for a few seconds? Rather pointless to terraform if you don't end up with a terraformed planet, I would think.

[Cyclonebuster]

Life may already be here on our moon,the extra Co2 may help it along. Ever hear of Methane eating bacteria here on earth?

 

Lunar Impact Uncovered More Than Just Moon Water

 

Oct. 21, 2010: Nearly a year after announcing the discovery of water molecules on the moon, scientists have revealed new data uncovered by NASA's Lunar CRater Observation and Sensing Satellite, or LCROSS, and Lunar Reconnaissance Orbiter, or LRO—and it's more than just water.

The missions found evidence that lunar soil within shadowy craters is rich in useful materials. Moreover, the moon appears to be chemically active and has a full-fledged water cycle. Scientists also confirmed that 'moon water' was in the form of mostly pure ice crystals in some places.

 

These results are featured in six papers published in the Oct. 22 issue of Science.

 

The twin impacts of LCROSS and a companion rocket stage in the moon's Cabeus crater on Oct. 9, 2009, lifted a plume of material that might not have seen direct sunlight for billions of years. As the plume traveled nearly 10 miles above the crater’s rim, instruments aboard LCROSS and LRO made observations of the crater and debris and vapor clouds. After the impacts, grains of mostly pure water ice were lofted into the sunlight in the vacuum of space.

 

"Seeing mostly pure water ice grains in the plume means water ice was somehow delivered to the moon in the past, or chemical processes have been causing ice to accumulate in large quantities," said Anthony Colaprete, LCROSS project scientist and principal investigator at NASA's Ames Research Center.

 

In addition to water, the plume contained "volatiles." These are compounds that freeze in the cold lunar craters and vaporize easily when warmed by the sun. The suite of LCROSS and LRO instruments determined as much as 20 percent of the material kicked up by the LCROSS impact was volatiles, including methane, ammonia, hydrogen gas, carbon dioxide and carbon monoxide.

 

"The diversity and abundance of volatiles in the plume suggest a variety of sources, like comets and asteroids, and an active water cycle within the lunar shadows," says Colaprete.

 

The instruments also discovered relatively large amounts of light metals such as sodium, mercury and possibly even silver. Scientists believe the water and mix of volatiles that LCROSS and LRO detected could be the remnants of a comet impact. According to scientists, these volatile chemical by-products are also evidence of a cycle through which water ice reacts with lunar soil grains.

 

LRO's Diviner instrument gathered data on water concentration and temperature measurements, and LRO's Lunar Exploration Neutron Detector mapped the distribution of hydrogen. This combined data led the science team to conclude the water is not uniformly distributed within the shadowed cold traps, but rather is in pockets, which may also lie outside the shadowed regions.

The proportion of volatiles to water in the lunar soil indicates a process called "cold grain chemistry" is taking place. Scientists also theorize this process could take as long as hundreds of thousands of years and may occur on other frigid, airless bodies such as asteroids; the moons of Jupiter and Saturn (including Europa and Enceladus); Mars' moons; interstellar dust grains floating around other stars and the polar regions of Mercury.

 

"The observations by the suite of LRO and LCROSS instruments demonstrate the moon has a complex environment that experiences intriguing chemical processes," said Richard Vondrak, LRO project scientist at NASA's Goddard Space Flight Center. "This knowledge can open doors to new areas of research and exploration."

By understanding the processes and environments that determine where water ice will be, how water was delivered to the moon and its active water cycle, future mission planners might be better able to determine which locations will have easily-accessible water. The existence of mostly pure water ice could mean future human explorers won't have to devise complicated processes to retrieve water out of the soil in order to use it for valuable life support resources. In addition, an abundant presence of hydrogen gas, ammonia and methane could be exploited to produce fuel.

 

"NASA has convincingly confirmed the presence of water ice and characterized its patchy distribution in permanently shadowed regions of the moon," concludes Michael Wargo, chief lunar scientist at NASA Headquarters in Washington. "This major undertaking is the one of many steps NASA has taken to better understand our solar system, its resources, and its origin, evolution, and future."

 

 

http://science.nasa.gov/science-news/science-at-nasa/2010/21oct_lcross2/