Terraforming Venus

[modest]

Originally Posted by Moontanman

Actually the loss of water can be atributed to the lack of a magnetic feild. Loss of water means that all the planets CO2 is in the atmosphere. this accounts for the greenhouse effect, pretty straight forward to me. oh yeah slow rotaion probably accounts for the lack of a magentic feild which could have been caused by a giant impactor that hit in the dead wrong orieintation to it's original rotation.

So what you're saying is that a planet with no water but with a magnetic field may well look like Venus.

[CraigD]

Originally Posted by modest

Why would Venus have it's Oxygen stripped off and not it's Nitrogen? Oxygen is heavier.

This is a good question, and not for which my understanding of the physics involved is adequate.

Via the recent (2006) Venus Express probe, we have for the first time precise, reliable observations that, at present, Venus is venting hydrogen, oxygen, and helium at a ratio (by count of atoms) of about 1.9:1:0.07, and essentially no nitrogen. (source: The loss of ions from Venus through the plasma wake). Note that, since the density of escaping atmosphere is small compared to that of the solar wind, there is an assumption that nearly all escaped atmosphere is ionized into plasma state, and that neutral molecules and atoms are little effected by the solar wind compared to ionized ones.

For so much of oxygen to be escaping, and for the H:O ratio to be so close to water’s 2:1, something other than simple Jean’s escape (in which the lightest elements, having the highest average velocity and thus the greatest number of molecules exceeding escape velocity) is responsible. The observed ratios suggest it’s related to water.

My best guess is that the dominant factor is how the Venusian atmosphere is segregated by altitude, resulting in a lot of O+ ions and hardly and nitrogen high up in the ionosphere where it can be stripped by collision with the solar wind. Speculating way over my head, I think a major mechanism for this may be the photochemical reaction of UV light with Venus’s atmosphere’s ubiquitous to produce and singlet , driven by oxygen’s slightly lower ionization energy than nitrogen and the Venusian atmosphere’s complicated convection patterns.

Somehow, something is putting a lot of O+ into Venus’s ionosphere, where it’s knocked into space by the solar wind. Why the H+:O+ ratio is so close to 2:1 mystifies me.

Originally Posted by Moontanman

… maybe the oxygen didn't get stripped from the atmosphere but it reacted with the surface and other chemicals to form the sulfer dioxide and sufuric acid seen in the atmosphere. I'm not sure but I think it would also form nitric acid as well.

Although there’s a lot of chemistry going on in the Venusian atmosphere, in terms of significant quantities of elements, it’s pretty much just 96.5% and 3.5% . Even it’s , the next most abundant compound and main constituent of its thick clouds, comprise only about 0.015% of the atmosphere. So, compared to its quantity of atmospheric , I don’t think atmospheric nitrogen compounds are very significant.

Originally Posted by Moontanman

One thing is sure oxygen would not be stable in the atmosphere of Venus with out a contuinous source of resupply. On the earth plants do that. I don't think Venus has much in the way of plant life.

I agree. Another important terrestrial carbon-cycle mechanism is the uptake of by seawater into carbonic acid (), which, having no oceans, Venus also lacks.

Artificial carbon-fixing schemes for Venus are popular hard science fiction subjects. For example, In the fictional universe of Steven Baxter’s 2004 novel “Exultant”, humans seed the Venusian atmosphere with artificially engineered “bugs” in tiny water droplets, which make more of themselves and form carbon-oxygen-polymer shells that fall out of the atmosphere to form a hundred-meter thick layer of chalk, not to terraform Venus, but because of the engineering value of such a large amount of carbon, resulting in Venus coming to be commonly known only as “the carbon mine”.

Not every planet-scale engineering project need have as an end making human-friendly worlds.

[CraigD]

Originally Posted by Moontanman

Actually the loss of water can be atributed to the lack of a magnetic feild.

Because atmosphere loss, whether for Venus, with a magnetopause averaging only 0.3 planetary radii above its surface, or for Earth, with a magnetopause averaging 15 radii, is due to losses from the outermost layers of their atmospheres, Venus’s smaller magnetosphere (note that despite its lack of an internally-generated magnetic field, Venus still has a magnetosphere) can’t be the direct cause of loss of water, because water is not found in either planet’s upper atmosphere.

Venus clearly appears to lack much water. Although its thick atmosphere (93 time the mass of Earth’s, and 92 times its surface pressure) has more of most compounds and elements than Earth’s, at a mere 0.002% water vapor, vs. Earth’s average of about 1%, it has less than 1/5th Earth’s water vapor, and apparently no liquid water. Venus is very hot, and very dry.

The scientific consensus, as I read it, is that Venus’s lack of water is due simply to its temperature, which despite its immense atmospheric pressure, remains well above the boiling point of water. A strong greenhouse gas, the vaporization of effectively all of Venus’s ancient water set in motion an evolution that resulted in the atmosphere we presently observe.

In short, I think the physics and evidence indicate that temperature, not magnetic field, is the dominant cause of the transformation of a once liquid-water rich, Earth-size planet like Venus into its present condition. Even if Venus had a magnetic field as strong or stronger than Earth’s, it wouldn’t have evolved much differently. If Earth were heated as strongly as Venus, despite its magnetosphere, it would evolve similarly to Venus. For this to happen as it did with Venus, the Sun would have to be roughly times its current brightness.

[Moontanman]

Originally Posted by modest

So what you're saying is that a planet with no water but with a magnetic field may well look like Venus.

Yes if it is close enough to the sun, too far away the CO2 will freeze out in high clouds that will reflect even more sunlight and the CO2 will snow out on the surface as Frozen CO2 much like Mars! CO2 stays because it isn't easy to break down by solar radiation as water is. actually to be precise loosing hydrogen is what messed up venus.

[Moontanman]

Originally Posted by CraigD

Because atmosphere loss, whether for Venus, with a magnetopause averaging only 0.3 planetary radii above its surface, or for Earth, with a magnetopause averaging 15 radii, is due to losses from the outermost layers of their atmospheres, Venus’s smaller magnetosphere (note that despite its lack of an internally-generated magnetic field, Venus still has a magnetosphere) can’t be the direct cause of loss of water, because water is not found in either planet’s upper atmosphere.

Venus clearly appears to lack much water. Although its thick atmosphere (93 time the mass of Earth’s, and 92 times its surface pressure) has more of most compounds and elements than Earth’s, at a mere 0.002% water vapor, vs. Earth’s average of about 1%, it has less than 1/5th Earth’s water vapor, and apparently no liquid water. Venus is very hot, and very dry.

The scientific consensus, as I read it, is that Venus’s lack of water is due simply to its temperature, which despite its immense atmospheric pressure, remains well above the boiling point of water. A strong greenhouse gas, the vaporization of effectively all of Venus’s ancient water set in motion an evolution that resulted in the atmosphere we presently observe.

In short, I think the physics and evidence indicate that temperature, not magnetic field, is the dominant cause of the transformation of a once liquid-water rich, Earth-size planet like Venus into its present condition. Even if Venus had a magnetic field as strong or stronger than Earth’s, it wouldn’t have evolved much differently. If Earth were heated as strongly as Venus, despite its magnetosphere, it would evolve similarly to Venus. For this to happen as it did with Venus, the Sun would have to be roughly times its current brightness.

Actually newer research seems to indicate the biosphere of the earth could maintain a much more equitable temperature on the earth even with the extra radiation. Probably too hot for much in the way of complex life but not the hot house Venus is today. As long as the oceans do not boil away CO2 is sequestered in the rocks. Higher temps do cause the atmosphere to puff out from the surface higher where solar radiation can strip hydrogen from water. Without a magnetic field this happens much faster than it does on the Earth. There is no doubt that lack of a magnetic field will accelerate the loss of volatile compounds from a planets atmosphere. There is no reason to assume Venus didn't have as much water the earth does. It simply lost it to space by loosing hydrogen to the solar wind. When I say radiation I am not talking about electromagnetic radiation alone. I am also talking about the solar wind. The solar wind will blow away the lighter elements of a planets atmosphere, Hydrogen especially. There is also no doubt that higher temps would allow more water vapor into the planets atmosphere which would put more water in harms way so to speak. Venus is not so close to the sun it's surface temperature would automatically be higher than the boiling point of water. The Earth average temperature isn't very high, we forget that sometimes because most of us live where the temps stay well above freezing most of the time. Venus wouldn't have ice caps but it could maintain oceans if not for its lack of hydrogen. A magnetic field of suitable strength will slow this process down by orders of magnitude. For hydrogen to be stripped from water it doesn't have to be at the edge of the atmosphere but extra heating will cause the atmosphere to be larger than it is in a lower temperature environment. The earth is loosing hydrogen as well just at a much slower rate than Venus. At some point the Earth will loose enough of it's hydrogen i.e. water for CO2 to start coming out of the rocks at a much higher rate than it is being put back. When this happens the CO2 level will begin to rise accelerating this effect by raising temps and puffing out the Earth atmosphere, run away greenhouse is what results. But as long as the Earth has a significant magnetic field this will still be a slower process than it was on Venus without a magnetic field. Of course as the Earth cools and it looses it's molten core it will also loose it's magnetic filed as well. The Moon will also slow the Earth's spin accelerating this process somewhat. So many feed back mechanisms I loose track!

[Moontanman]

Originally Posted by CraigD

This is a good question, and not for which my understanding of the physics involved is adequate.

Via the recent (2006) Venus Express probe, we have for the first time precise, reliable observations that, at present, Venus is venting hydrogen, oxygen, and helium at a ratio (by count of atoms) of about 1.9:1:0.07, and essentially no nitrogen. (source: The loss of ions from Venus through the plasma wake). Note that, since the density of escaping atmosphere is small compared to that of the solar wind, there is an assumption that nearly all escaped atmosphere is ionized into plasma state, and that neutral molecules and atoms are little effected by the solar wind compared to ionized ones.

For so much of oxygen to be escaping, and for the H:O ratio to be so close to water’s 2:1, something other than simple Jean’s escape (in which the lightest elements, having the highest average velocity and thus the greatest number of molecules exceeding escape velocity) is responsible. The observed ratios suggest it’s related to water.

My best guess is that the dominant factor is how the Venusian atmosphere is segregated by altitude, resulting in a lot of O+ ions and hardly and nitrogen high up in the ionosphere where it can be stripped by collision with the solar wind. Speculating way over my head, I think a major mechanism for this may be the photochemical reaction of UV light with Venus’s atmosphere’s ubiquitous to produce and singlet , driven by oxygen’s slightly lower ionization energy than nitrogen and the Venusian atmosphere’s complicated convection patterns.

Somehow, something is putting a lot of O+ into Venus’s ionosphere, where it’s knocked into space by the solar wind. Why the H+:O+ ratio is so close to 2:1 mystifies me.Although there’s a lot of chemistry going on in the Venusian atmosphere, in terms of significant quantities of elements, it’s pretty much just 96.5% and 3.5% . Even it’s , the next most abundant compound and main constituent of its thick clouds, comprise only about 0.015% of the atmosphere. So, compared to its quantity of atmospheric , I don’t think atmospheric nitrogen compounds are very significant.I agree. Another important terrestrial carbon-cycle mechanism is the uptake of by seawater into carbonic acid (), which, having no oceans, Venus also lacks.

Artificial carbon-fixing schemes for Venus are popular hard science fiction subjects. For example, In the fictional universe of Steven Baxter’s 2004 novel “Exultant”, humans seed the Venusian atmosphere with artificially engineered “bugs” in tiny water droplets, which make more of themselves and form carbon-oxygen-polymer shells that fall out of the atmosphere to form a hundred-meter thick layer of chalk, not to terraform Venus, but because of the engineering value of such a large amount of carbon, resulting in Venus coming to be commonly known only as “the carbon mine”.

Not every planet-scale engineering project need have as an end making human-friendly worlds.

I agree but wouldn't Titan make a better carbon mine than Venus? Lower gravity, higher in the suns gravity well? Bring carbon in from Titan would be easier than bringing it out from Venus wouldn't it?

[Moontanman]

So much speculation, so little time!

[modest]

Originally Posted by CraigD

Via the recent (2006) Venus Express probe, we have for the first time precise, reliable observations that, at present, Venus is venting hydrogen, oxygen, and helium at a ratio (by count of atoms) of about 1.9:1:0.07, and essentially no nitrogen.

Very interesting. And, quite the puzzle considering your next post.

Very good info indeed.

-J

[Boerseun]

Haven't read all replies, so excuse me if I repeat a point:

Terraforming Venus is a useless effort. Whether it can me done mechanically or biologically, won't help at all.

And it's all about Venus' rotation period.

Say you get the atmosphere to simulate Earth's, a nice and homely nitrogen/oxygen atmosphere befitting us two-legged beasts of pollution.

Won't help.

And simply 'cause however nice you make the atmosphere, a day lasting in excess of a hundred Earth days will make the one side unbearably hot for months on end, and the other side frozen over.

No plants can survive conditions like that (save some very extreme extremophiles, I guess). And, no plants, no agriculture, no humans.

If you've got the atmopshere sorted, you're gonna have to speed that ball of rock up some. By quite a bit. So, forget Venus, in my honest, albeit a bit negative, though thoroughly realistic, opinion.

[Ahmabeliever]

Awww

And I was so enjoying the discourse

Certainly is great food for sci-fi.