Wet Venus? 9
Porfiry writes "Researchers at Washington University in St. Louis, studying hydrous mineral decomposition rates at extreme temperatures, have concluded that hot and dry Venus may have been a wet planet in the past, like Earth and ancient Mars. The new evidence suggesting a wetter Venusian history comes from a series of experiments documenting the chemical stability of tremolite, a mineral that forms in the presence of water." This is a little bit similar to the Venus article we just posted, but still interesting.
Re:Life on Venus? (Score:1)
They live by oxidizing the minerals around them like Cr to Cr+2 (please pardon any possible chemistry mistake).
If people can connect to one another even the smallest of voices will grow loud.
This article is just askin' for it! (Score:1)
If that title isn't flamebait, then I don't know what is.
Re:Life on Venus? (Score:1)
yes, and the surface has turned itself inside out (Score:1)
Re:Life on Venus? (Score:1)
Who says that life has to use water and oxygen for metabolism? I wouldn't be surprised if there were lifeforms found that used other materials for existence, such as carbon dioxide, methane, sulphuric acid, etc.
Just because humans can't use it doesn't mean that there aren't other lifeforms that can.
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Re:Life on Venus? (Score:2)
I don't think we need to invoke magical "life using up resources" scenarios to explain climate changes on Mars and Venus. Their own structure and location does this well enough.
For Mars: Mars is large enough to hold a thick atmosphere for a while, but small enough that it won't hold it over geological time. It started with composition similar to most of the inner solar system, and lost its volatiles (including water and most of its atmosphere) over succeeding eons. Bacterial life may or may not have had time to evolve or be seeded before this, but atmosphere loss made it moot (for the planet's surface, at the very least).
For Venus: I personally have doubts about this planet ever being a nicer place than it currently is. The article doesn't claim that it is; it only presents a method to test for a more water-rich past. At any rate, the presence or absence of water on Venus doesn't change much. It's close to the sun, and doesn't have a big moon to strip away most of its atmosphere like Earth did. As soon as it had an appreciable atmosphere (probably always; it would have formed with the planet), runaway greenhouse effects took over. Water would actually have helped this happen.
Bacteria might exist on Venus. We don't know yet.
In both cases, the presence or absence of bacteria doesn't do much to affect the planetary climate.
Now, for the special case, Earth. Earth is the only planet that we know of where bacteria *did* play a big role in shaping the composition of the atmosphere. They didn't make earth more hospitable by doing it - on the contrary, they could only do it because Earth was so hospitable in the first place (thus leaving them billions of years to work in). Earth owes its wonderful climate to good positioning (just the right amount of sunlight), large mass (enough to keep an atmosphere over geological time), and and a large moon (to strip away most of the atmosphere early in Earth's history, preventing another "Venus").
Even the case for Earth's oxygen atmosphere being the result of the work of bacteria is an open question. Earth's gravity well is deep enough to hold on to heavy molecules like nitrogen and oxygen, but if free hydrogen ever forms, it can escape (albeit slowly). Photoionization of water and ammonia and methane in Earth's early reducing atmosphere would have liberated enough hydrogen to gradually change the composition of Earth's atmosphere to be dominated by other elements.
Today, in Earth's later years, life has an important role regulating the transport of carbon from rocks to the atmosphere and back, but the lion's share of the work was done without life's help.
Life on Venus? (Score:2)
Re:Life on Venus? (Score:2)
One branch of this theory indicates that the probability was very large that the original seeds for this life would come from "somewhere" else, ride into the solar system on commets or metorites and fall to the three planets at around the same time. Of course, the questions that this raises are why did life continue to develop on Earth when something disastorous happened on the other planets to prevent it. The possibilities there are endless.
My favorite theory is that the other two planets were actually much more suited to whatever form of life originally seeded them, the Earth being just a little different in sunlight penetration and a few chemical balancing acts. The other two planets therefore flourished quickly, the simple lifeforms used up the resources that were available quickly, and this caused, slowly at first, a change in climate. But once that change was set in motion it never ceased until we end up with the two completely unlivable (by our standards) planets and the completely habitable (again by our standards) Earth.
If any of this is true (and it's mostly speculation with very little scientific research dedicated to it, as it isn't a popular thought), the additional question would be if any of those simple life forms were able to adapt or retreat below the surface of either Mars or Venus. It's a fascinating idea.
Of course, to make a good sci-fi story we would have to say that all three planets developed simultaneously, there was a huge civilization on all three planets, with lots of trade between them. And one day one of the planets (those damn greedy Earthlings) got pissed off because the other planets were prettier and nicer to live on. So they developed this ultimate weapon that would quickly alter or destroy a planet's atmosphere.
*POOF* But, getting back to reality....;-)
Re:Life on Venus? (Score:3)
As theoretical models, sulfuric acid chemistry could possibly be used by organism based on silicone (SiO) chains instead of carbon chains.
And a reaction that converts CO2 into stored CO, and releases energy with a 2 CO = C + CO2 reaction is also a theoretical possibility -- a cycle that would happen to release free oxygen, like the article mentions was detected on Venus, which has an atmosphere of mostly CO2...