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View Full Version : Could life have origionated on Venus



Michael Noonan
2007-Sep-05, 09:29 AM
Now I don't want to defend this as ATM as I really don't know, but given the sun was cooler say 500 million years ago could it have been hypothetically possible?

The reason I ask is there have been a couple of very interesting ATM and other ideas, I just would like to know given the 'right conditions' or is it a case of it simply can't be done.

Michael Noonan
2007-Sep-05, 10:35 AM
Two views in an hour and one of them mine. Oh well I didn't think it could be done.

I suppose the follow up question would be has anyone calculated the runaway greenhouse effect for earth and what atmospheric pressure would be at the surface with all the gases that are available?

And if the earth got to the present temperature of Venus what atmospheric make up would the earth have at that temperature?

Essan
2007-Sep-05, 10:43 AM
Can't see any reason why life might have originated on Venus - if it could emerge there it could surely just as likely emerge independently on Earth.

As for runaway greenhouse - doesn't look likely to happen on Earth. There are thought to have been massive releases of methane hydrates in the past, giving rise to amongst other thing, the P-T Extinction event (or, at least contributing to it) and the Paleocene-Eocene Thermal Maximum. In both cases CO2 levels eventually returned to 'normal'. It's been speculated that CO2 levels at times in the Cretaceous could have been up to 4,000ppm (compared with current 385ppm). Oceans, life and plate tectonics all work to remove CO2 from the atmosphere and maintain an equilibrium. We'd need to switch those mechanism off in order to get a runaway greenhouse like Venus.

mfumbesi
2007-Sep-05, 11:47 AM
Outside Barberton in South Africa the are rocks with fossils which are believed to be ~3.2 billion years. Earth has had life for a long time, as Essan stated above life could have independently emerged on Earth.
Here is link:http://en.wikipedia.org/wiki/Chert

jlhredshift
2007-Sep-05, 11:56 AM
IIRC it is conjectured that Venus may have had water very early on; within the first billion years or so. However, what I find even more interesting is the amount of carbon and oxygen on Venus. The total mass of the atmosphere of Venus and Earth respectively is 4.8 x 1020 and 5.1 x 1018 kilograms, 96.5% of which is CO2 on Venus. That is a 100 times more massive atmosphere on Venus, and correspondingly the surface pressure is 92 bars versus 1.014 bars respectively. That is a lot of carbon and oxygen by mass, whereas the moon is virtually devoid of carbon and we have a little by comparison. Why did Venus accumulate this disproportinate share?

Michael Noonan
2007-Sep-05, 02:45 PM
IIRC it is conjectured that Venus may have had water very early on; within the first billion years or so. However, what I find even more interesting is the amount of carbon and oxygen on Venus. The total mass of the atmosphere of Venus and Earth respectively is 4.8 x 1020 and 5.1 x 1018 kilograms, 96.5% of which is CO2 on Venus. That is a 100 times more massive atmosphere on Venus, and correspondingly the surface pressure is 92 bars versus 1.014 bars respectively. That is a lot of carbon and oxygen by mass, whereas the moon is virtually devoid of carbon and we have a little by comparison. Why did Venus accumulate this disproportinate share?

Thank you jlhredshift it was something that had me curious.

I had wondered if all the locked in carbon say the carbon in coral, plants and rock was released on earth due to global warming. Then would it with water vapour be able to react to produce heavier gases like the sulphuric acid venusian atmosphere causing a higher atmospheric pressure?

I didn't realise just how much more carbon dioxide Venus had, that is a lot.

jlhredshift
2007-Sep-05, 03:10 PM
Thank you jlhredshift it was something that had me curious.

I had wondered if all the locked in carbon say the carbon in coral, plants and rock was released on earth due to global warming. Then would it with water vapour be able to react to produce heavier gases like the sulphuric acid venusian atmosphere causing a higher atmospheric pressure?

I didn't realise just how much more carbon dioxide Venus had, that is a lot.

You are welcome. I probably should have given a source in my prior post so here (http://burro.astr.cwru.edu/stu/advanced/venus.html) it is.

korjik
2007-Sep-05, 07:30 PM
IIRC it is conjectured that Venus may have had water very early on; within the first billion years or so. However, what I find even more interesting is the amount of carbon and oxygen on Venus. The total mass of the atmosphere of Venus and Earth respectively is 4.8 x 1020 and 5.1 x 1018 kilograms, 96.5% of which is CO2 on Venus. That is a 100 times more massive atmosphere on Venus, and correspondingly the surface pressure is 92 bars versus 1.014 bars respectively. That is a lot of carbon and oxygen by mass, whereas the moon is virtually devoid of carbon and we have a little by comparison. Why did Venus accumulate this disproportinate share?

do you know how much CO2 is bound up in limestone? I am wondering if that could be most of the mass in carbon required for Earth's atmo to become like Venus' atmo

jlhredshift
2007-Sep-05, 07:55 PM
do you know how much CO2 is bound up in limestone? I am wondering if that could be most of the mass in carbon required for Earth's atmo to become like Venus' atmo

No, and I also do not know what the current global sedimentation rate is. There are specific locations that are known, and extrapolations can be made, but no precise knowledge. Also, CaCO3, calcium carbonate, has only one atom of carbon per molecule. Therefore, limestoneis mostly calcium and oxygen by mass. The seafloor is mostly basalt with a film, geologically speaking, of organic deposits and the continents are igneous basalts covered in SiAl, silicon and aluminum that are oxidized, sand, and a film of organic debris. The continental shelf is the primary production site for limestone and therefore is only a fraction of the Earth's surface. So,best guess, there is nowhere near enough carbon to duplicate the atmosphere of Venus.

(and my darned space bar is sticking again)

And I need to add all the sedimentary rocks from all ages on the continents that contain calcium carbonate.

galacsi
2007-Sep-05, 08:31 PM
In fact there is roughly the same amount of C02 on Earth and on Venus.

From the url below :
On Earth, atmospheric CO2 is absorbed by precipitation- --by rain---and forms a very weak solution of carbonic acid, a very mild form of acid rain. This acid rain falls on surface rocks, many of which contain calcium, and the carbonic acid dissolves a tiny bit of the calcium. Eventually the water, containing both carbonic acid and calcium ions, washes down to the ocean. In our oceans tiny plants and animals, plankton, incorporate the calcium and carbonic acid into shells of calcium carbonate. When the animals die, their calcium carbonate exoskeletons drift to the ocean floor. When enough of these carbonate deposits build up, they form carbonate rocks, such as limestone, which are composed of the skeletons of trillions of dead plankton. In short, the action of water removes CO2 from the atmosphere and puts it into the crust of the Earth. The Earth has roughly the same amount of CO2 as does Venus, but it is nearly all locked up in the crust as carbonate sediments.

http://www.phys.lsu.edu/faculty/cjohnson/climate.html

EvilEye
2007-Sep-05, 08:37 PM
Why not just look at all 3 planets as the same at different stages of life?

Venus as the baby, Earth as the adult, and Mars as elderly?

jlhredshift
2007-Sep-05, 08:41 PM
In fact there is roughly the same amount of C02 on Earth and on Venus.

From the url below :

http://www.phys.lsu.edu/faculty/cjohnson/climate.html

The carbon cycle is described very nicely on that web page and I was hoping that there would be a reference for the calculation of equivalancy of the mass of carbon.