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Maxinquaye
03-29-2011, 12:01 PM
I'm writing a novella set in space, and I've been thinking about ways to make Venus habitable without inventing magical remedies, and one of the things I've come up with is a disc in orbit around the sun that would block out much sunlight.

Think of it as a huge circular filter that rotates in an orbit around the sun at a speed so that it matches Venus orbit. I'm not much of a mathematician, or a chemist, so I might be totally delusional.

Would this work as a remedy to bring the temperature down to earth-like temperature? Am I barking up the wrong tree here, and should I then magically "fix" the greenhouse effect of the atmosphere?

I most likely will have to invent scrubbing devices for the atmosphere as well, to move it towards a more earth like atmosphere over time in a far future, but that could be skipped over pretty much as just a reference. The 'melting lead temperature' is something that can't be overlooked however.

ETA: I should add that this was seriously proposed by scientists at the Lawrence Livermore laboratory to combat global warming.

http://www.popsci.com/environment/article/2005-06/how-earth-scale-engineering-can-save-planet?page=3

Kenn
03-29-2011, 01:50 PM
The biggest problem is all of the carbon dioxide. It means the surface pressure is so high that you would not survive (like being at the bottom of the ocean). Get rid of this and you might be on to something, but how is another question altogether.

As for the ideas to cool Earth, they are whacky at best. It just might just be that changing the radiation balance of the planet would result in changes in the weather that are are catastrophic, to say the least;)

Sarpedon
03-29-2011, 04:59 PM
The disk sunblock is somewhat problematic. The thing is that an orbiting body must move at a precise speed in order to stay in a stable orbit. The closer it is to the thing its orbiting (ie, the sun) the faster it must go. Also, since it is closer, its orbit is smaller. Put these two facts together, and your sunshade just isn't going to stay put between Venus and the sun, unless it continuously uses rockets to keep station.

And as far as venus' atmosphere goes, Perhaps you can introduce a chemical to the atmosphere that would cause the greenhouse gases to preciptate down to the surface. Now what would do that at those temperatures is beyond me. This would both reduce the pressure and allow more heat to escape.

Or maybe you could just have a bunch of spaceships 'scooping' away the atmosphere. The captured gas could be shipped to space stations for reuse. I have no idea how long it would take to make any change this way.

LBlankenship
03-29-2011, 06:36 PM
As Kenn pointed out, the carbon dioxide and atmospheric pressure are a bigger problem than the sun, really.

I bet one could genetically engineer some kind of algae (or a fast-growing plant) to gobble up the CO2 and convert it to oxygen.

Sarpedon
03-29-2011, 07:49 PM
No algae could survive in such an environment. The heat would destroy the DNA.

Also, no water.

BunnyMaz
03-29-2011, 07:55 PM
An engineered, high-pressure resistant bacterium or algae released onto the planet to convert CO2 could work - once the greenhouse gasses are reduced the planet will cool somewhat, and then remaining temperature issues could be dealt with more easily.

Depending on how far-fetched and far-ahead sci fi you're going for... are molecule-thick substances an option? Something incredibly thin and light filtering out the sunlight...

PeterL
03-29-2011, 08:35 PM
Turning the hydrocarbons in the atmosphere into water, solid carbon, and O2 would help, but you would have to eliminate the amount of atmosphere. I have never seen estimates of the quantities of each component in Venus' atmosphere, so I don't know whether converting those gases into H2O and O2 would decrease the surface pressure enough.

LBlankenship
03-29-2011, 09:33 PM
No algae could survive in such an environment. The heat would destroy the DNA.

Also, no water.

We've got extremophiles living here on Earth at ridiculous temperatures.

Water is trickier... though I'm sure some microbe out in the Sahara (or better yet, the Antarctic deserts) has figured out something.

But anyway, get all that carbon out of the air and locked up in physical structures. That's a start at lightening up the atmosphere.

Nick Blaze
03-29-2011, 10:06 PM
We know of organisms that survive off of arsenic, too.

Hallen
03-29-2011, 10:52 PM
You've got bigger problems yet again in that Venus has no magnetic field. Any real atmosphere that you generate is going to be blown off into space by the solar winds. You have no water and no hydrogen, probably because of this. Also, it's speculated that the planet releases internal heat via massive eruptions instead of smaller volcano eruptions like we have here. So, every so often, everything on the surface gets wiped out. (but that's speculation right now).

Your only hope for a human survivable situation is some kind of massive dome or sub-surface dwelling and some damn fine machines that can create oxygen and water out of whatever the planet can provide.

Maxinquaye
03-29-2011, 10:56 PM
Your only hope for a human survivable situation is some kind of massive dome or sub-surface dwelling and some damn fine machines that can create oxygen and water out of whatever the planet can provide.

Yes, the venusians live in underground complexes while they wait for the atmosphere to get cleaned. I've just looked at the heat as a problem, and sought to bring it down to more moderate temperatures so that the "tanks" they use for surface vehicle don't melt and/or cook their passengers.

But it looks like I have to revisit this and repopulate the people elsewhere. Thanks all!

Sarpedon
03-29-2011, 11:23 PM
We've got extremophiles living here on Earth at ridiculous temperatures.



At high temperatures, yes. But not at 'melts aluminum' temperatures.

Average venus surface temperature: 735 C.

Deep sea vent temperature 60-675 C.

And why would you think that living in underground complexes would be any cooler than the surface? The reason its cool underground on earth is because that temperature indicates the rough average of the Earth's surface temperature; (cooled by our oceans) it retains its temperature because of its mass, evening out the peaks of the surface temperature.

Venus probably has a molten core, like the earth. Unlike the earth, excess heat does not escape into space fast enough to cool the crust. It is likely that the surface temperature is the minimum temperature, and the temperature rises from 675C to the core temp, which is probably similar in temperature to ours: 5800C.

Think about it, the underground temperature will be high because there is no place the heat can go.

If it were me, I'd wait in a space station.
I'm willing to bet the bacteria don't live in the part where the temperature is 675C

Maxinquaye
03-29-2011, 11:32 PM
Well, my idea was that the Venus in my story has a high tropical average temperature due to the sunscreen that blocks out 50% or so of the sunlight, and if that is the case then the pressure and the volatility of the atmosphere would be greater danger than geothermal temperature. A dome might conceivably be in danger due to storms and stuff, unless you dug it into the ground.

If I didn't have the sunscreen, in my idea here, then the biggest danger would be the temperature. But it would be compounded by the pressure, the storms, the sulphuric acid, and so on. Just trying to not compound the dangers to my venusians. :)

jaksen
03-30-2011, 02:36 AM
Wasn't there a species of vine-like plant that gobbled up a lot of the carbon dioxide at the beginning of the Triassic Period? (End of Permian?) I am remembering faintly a NOVA or other television show that said these vines were everywhere. Life was really suffering at this time; temperatures were up; drought conditions worldwide; carbon dioxide in the atmosphere at its highest levels.

Anyhow, the vine sort of saved life on the planet. I am not googling this, just relying on memory. I think it happened on Earth, or some theories say it did.