Author Topic: Sun Shade concepts for Venus  (Read 47015 times)

Offline Andrew_W

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Re: Sun Shade concepts for Venus
« Reply #40 on: 09/19/2011 11:18 PM »
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There have been suggestions of seeding genetically modified algae into the Venusian atmosphere.

Algae have had hundreds of millions of years to colonize the atmosphere of Earth but the sky is still blue.
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Offline Solman

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Re: Sun Shade concepts for Venus
« Reply #41 on: 09/21/2011 02:27 PM »
Quote
There have been suggestions of seeding genetically modified algae into the Venusian atmosphere.

Algae have had hundreds of millions of years to colonize the atmosphere of Earth but the sky is still blue.

 If however there were balloon-borne ribbons of water absorbent material filling the sky there would at least be some green to the vista.
For a completely biological approach you could imagine lichen-like life forms with large hydrogen filled balloon-like structures floating in the sulphuric acid clouds excreting sulphur as they break the acid down into water. Or maybe not.
 I had the idea years ago of solar powered factories hung from acid derived hydrogen balloons floating high in the atmosphere that would break the CO2 down and form oxygen filled diamond bubbles or balloons with velcro like surfaces. The factories would drop them into the lower atmosphere where they would loosely stick together to form islands then continent sized islands and finally perhaps cover virtually the whole lower atmosphere. The atmosphere is gradually thinned and eventually the islands come to rest on the surface. The atmosphere would be sequestered. I know its half-baked but I hope amusing anyway.


     

Offline AlexCam

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Re: Sun Shade concepts for Venus
« Reply #42 on: 12/18/2011 01:50 PM »
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There have been suggestions of seeding genetically modified algae into the Venusian atmosphere.

Algae have had hundreds of millions of years to colonize the atmosphere of Earth but the sky is still blue.

Earth's atmosphere is not comparable to the atmosphere of Venus.

Offline Lampyridae

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Re: Sun Shade concepts for Venus
« Reply #43 on: 12/19/2011 07:19 AM »
I presented a paper on this back in my Hons year. The big thing that's missing is the fact that carbon dioxide is baked out of rock, and can be locked back into it. Venus' CO2 atmosphere came from a gradual period of calcination as it was cooked out of carbonate rocks. Reduce the temperature, and the metal oxides combine with CO2 to form carbonate rocks. Water would help this a lot.

The removal of CO2 from the atmo combined with falling temperatures results in a lot of rock fracturing. A lot depends on the porosity or potential porosity of the Venusian rock, which I really know nothing about.

It would take a while, but the unloading of 1km worth of CO2 would also create plenty of rock fracturing, not to mention cooling down even a few dozen degrees K - this a planet that knows hardly any temperature differentials. At night, CO2 ice would collect at the highest mountains, Ishtar Terra for example. Colonisation might actually be possible in the valleys, rather, with the CO2 plateaus reducing a lot of the planet's albedo (but some kind of sunshade would still be necessary).

On the topic of sunshades, a simple cloud of asteroidal dust at L2 would do the job, sepherded with light pressure from nearby solar mirrors.
« Last Edit: 12/19/2011 07:46 AM by Lampyridae »
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Offline ApolloStarbuck

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Re: Sun Shade concepts for Venus
« Reply #44 on: 12/30/2011 09:38 AM »
Organic material can self replicate. There have been suggestions of seeding genetically modified algae into the Venusian atmosphere.

This Idea was often pushed by Carl Sagan.  IIRC he later backed off the concept.
The original idea was that genetically algae would be seeded in the upper atmosphere and consume the carbon dioxide, reproduce and continue until the gas was absorbed enough to cause a reverse runaway greenhouse effect.
He later stated that it probably wouldn't work because as the algae sank into the lower levels of the atmosphere, it would simply "burn up" and release the carbon it had absorbed in the first place. Plus, there's no appreciable amounts of hydrogen that the algae would need.

But if you want to think REALLY big, how about just swapping Venus and Mars orbits.  Venus, pushed out to Mars' orbit, would get a chance to cool down and still be in the  habitability zone and Mars, being moved closer to the Sun, would heat up and get a thicker atmosphere...for a little while at least  ;)
« Last Edit: 12/30/2011 09:49 AM by ApolloStarbuck »
...weren't we supposed to be on Mars by now?

Offline Bob Shaw

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Re: Sun Shade concepts for Venus
« Reply #45 on: 01/03/2012 02:13 AM »
The idea of simply freezing out the atmosphere of Venus isn't an adequate fix for the excess mass of the atmosphere. It has to be persuaded to go somewhere else, or else you're permanently on a knife-edge, waiting for the stuff to return to a gaseous state and ruin all your hard work.

The answer is to heat Venus up, and break the feedback systems which govern the current atmosphere. We need to puff as much as possible of the atmosphere up, so that it reaches a height where the Sun can erode it away into interplanetary space. In effect, the situation at Mars is applied to Venus (thin, high atmosphere), and as both planets lack serious magnetic fields we may expect the process to be quite effective.

How to heat the atmosphere? Well, an albedo change would help, plus input from mirrors. The sort of mirrors that might be used could be either reflective, or Fresnel lenses. In either case you might use mirrors which are not actually in orbit, but which use the pressure of sunlight to hang in space. The sheer size of the required mirror technology suggests that it might well be a spinoff from interstellar propulsion systems, which in turns invites the use of the sort of intra-Mercurian laser cannon which are often posited for 'stay-at-home' starship propulsion devices, but repurposed to heat up Venus instead. Another option would be to move to the realm of masers to heat the upper reaches of the atmosphere (natural CO2 maser activity in the atmosphere of Mars was proposed decades ago). Ideally, of course, we use the Sun to do the job of both heating and erosion.

Once you have eroded the atmosphere your cooling job becomes much simpler, and as previously stated a nice little dust cloud factory at the inner LaGrange point would be a fairly cheap start.

Overall, though, the sort of resources and technology which are required to cool Venus are on a par with those required for interstellar flight.

Offline Danderman

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Re: Sun Shade concepts for Venus
« Reply #46 on: 01/03/2012 02:16 AM »
This is a little o/t, but I suspect that the actual solution to cooling Venus will involve moving some of its atmosphere, bit by bit, to Mars. Both planets would benefit from such an exchange. How that would happen is beyond me.


Offline kch

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Re: Sun Shade concepts for Venus
« Reply #47 on: 01/03/2012 03:40 AM »
This is a little o/t, but I suspect that the actual solution to cooling Venus will involve moving some of its atmosphere, bit by bit, to Mars. Both planets would benefit from such an exchange. How that would happen is beyond me.



Maybe something like this?



;)

Offline Danderman

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Re: Sun Shade concepts for Venus
« Reply #48 on: 01/03/2012 03:53 AM »
You have solved the problem.

Offline sojourner

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Re: Sun Shade concepts for Venus
« Reply #49 on: 01/03/2012 04:13 AM »
OK, this has always been a crazy idea of mine, and I know the science of it is really bad, but why not recreate the impact that gave Earth it's moon on Venus?  A food portion of the over abundant atmosphere is blown away, angular momentum is created,  the entire planet of Venus is basically "rebooted".  We just need to find a good Mars sized planet that no one is using....

Offline scienceguy

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Re: Sun Shade concepts for Venus
« Reply #50 on: 01/03/2012 04:18 AM »
F = ma.

Mars' mass is 10^23 kg. To accelerate something the size of Mars at 1 m/s^2, you need 10^23 N of force. The space shuttle main engines produced 10^6 N of force.
e^(pi)i = -1

Offline RocketmanUS

Re: Sun Shade concepts for Venus
« Reply #51 on: 01/03/2012 04:54 AM »
Have a device float on the upper atmosphere, bring in the CO2, convert it to C and O2, release O2, take carbon to high orbit to make an artificial satellite of carbon.

Harvest some of the CO2 to make CO and O2 for fuel to take O2 ( from some of the CO2 to make C and O2, carbon left in Venus high orbit as above ) to Mars by use of a reusable orbital transfer vehicle.

Craft to scoop up CO2 ( Venus top atmosphere to low Venus orbit )powered by CO/O2.

Station in low orbit takes the CO2 to make CO, O2, C from solar power. If manned then habitat part of station rotates to make 1G for crew.

Crazy, but can that be built on to make something practical.
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Offline Andrew_W

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Re: Sun Shade concepts for Venus
« Reply #52 on: 01/03/2012 05:43 AM »
There's around 460 million billion tonnes of CO2 in the Venusian atmosphere.
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Offline strangequark

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Re: Sun Shade concepts for Venus
« Reply #53 on: 01/03/2012 05:52 AM »
Have a device float on the upper atmosphere, bring in the CO2, convert it to C and O2, release O2, take carbon to high orbit to make an artificial satellite of carbon.
It would require roughly 1 billion times the total energy currently produced by the world in one year. Yes, I did the math. As far as using solar power, if you wished to accomplish it within 1000 years, using a 100% efficient solar array, with 100% efficient conversion to chemical energy stationed in Venus orbit, the required surface area is a bit more than the entire surface area of Earth.

As for the rest of the plan, everything else requires only slightly less ridiculous amounts of energy/power.

Any civilization capable of accomplishing this would have better way, like fusing the carbon and oxygen into metals...or magic.

Harvest some of the CO2 to make CO and O2 for fuel to take O2 ( from some of the CO2 to make C and O2, carbon left in Venus high orbit as above ) to Mars by use of a reusable orbital transfer vehicle.

Craft to scoop up CO2 ( Venus top atmosphere to low Venus orbit )powered by CO/O2.

Station in low orbit takes the CO2 to make CO, O2, C from solar power. If manned then habitat part of station rotates to make 1G for crew.
« Last Edit: 01/03/2012 05:56 AM by strangequark »

Offline colbourne

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Re: Sun Shade concepts for Venus
« Reply #54 on: 01/03/2012 09:31 AM »
To do this cheaply the answer would have to be biological so that only a few small rockets are needed. They would carry some form of life that can convert the CO2 to  an inert solid able to survive on the surface.

Moving large objects on to a collision course with low energy usage demands the luck of finding a suitable asteroid on very nearly the correct orbit to eventually collide. A very small nudge is all that is then required.

Offline alexterrell

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Re: Sun Shade concepts for Venus
« Reply #55 on: 01/04/2012 04:29 PM »
Zubrin had a proposal to fire MgO and CaO from Mercury to Venus. These react with CO2 to form solid carbonates, thereby precipitating out the atmosphere.

Yes - it's far off. It would require a solar powered mining device and linear accelerator, which can (now for the tricky part) replicate itself like a Von Neumann machine. 


Offline go4mars

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Re: Sun Shade concepts for Venus
« Reply #56 on: 01/04/2012 06:58 PM »
Zubrin had a proposal to fire MgO and CaO from Mercury to Venus. These react with CO2 to form solid carbonates, thereby precipitating out the atmosphere.

Yes - it's far off. It would require a solar powered mining device and linear accelerator, which can (now for the tricky part) replicate itself like a Von Neumann machine. 
As long as you promise to leave enough carbon for a nice Venusian diamond ring.  ;)

The refractive index of diamond means you could build a big honker, (or a bunch of smaller ones in geosync) orbiting Venus along the ecliptic, to divert a lot of sunlight around the whole planet.

Again. Von Neumann seems to have the most likely approach...
« Last Edit: 01/04/2012 07:02 PM by go4mars »
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Offline RocketmanUS

Re: Sun Shade concepts for Venus
« Reply #57 on: 01/26/2012 09:33 PM »
Venus atmosphere
source
http://en.wikipedia.org/wiki/Atmosphere_of_Venus

Height km      Temp. C          pressure in bar
0                    462                92.10 ( similar to 910 meters below the surface of the Ocean )
50                  75                  1.066 ( near Earth sea level )
100                -112                0.0000266

Clouds in Earth's atmosphere are said to have living bacteria in them. It is said that there could be bacteria in clouds in Venus's atmosphere. So there should be future probes to study Venus before it might be terraformed.

Most of the thermal energy is below  50km and and air volume. Sources of thermal energy are from the Sun and inside of Venus. Solar sails placed in Venus GSO and using Sun light to move them around as needed would block some of the incoming solar enery. Solar sails places farther away could partly or fully eclipse Venus from the Sun. This would help to cool the planet.

Once that is in place, machines would need to be sent to the surface.They would change the CO2 into solids that would be stable in the hight pressure and temperature at the surface and still be stable at low pressure and tempertures when the planet atmosphere is changed to more Earth like. Other compounds would need to be changed also. Reducing the pressure and changing the quantities of compounds in the air would help lower the atmospheric tempature. So the machines change the compounds in the air to solids to get rid of the excess mass in the atmosphere.

Also causing the lower air to mix with the upper air can help in bleeding off some of the heat to space on the night side of the planet. Winds on Venus can be used to our advantage if some or all of the solar energy is blocked on the day light side of Venus.

The machines will need power. They might be able to use the heat from the surrounding air as a source of energy at first. Later on as the temp and pressure goes down solar or nuclear power might be a source of energy.

Any way we look at this it is a big project. Most likely not to take place any time before 2050. We will need in space infrastructure such as space stations and lunar manufacturing. Plus quick cargo and crew transport ships between planets ( one way less than 21 days from Earth to Mars or Venus ), possibly powered by some sort of fussion powered engine.

By 2050 we should have solar sails by then and single or two stage low cost reusable launch vehicles and a moon base. So the price to terraform Venus will go down as our in space infrastructure goes up.
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Offline Da5id

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Re: Sun Shade concepts for Venus
« Reply #58 on: 01/30/2012 12:32 PM »
A lot of the ideas for sun shades seem to be away to expensive to adopt. I think it can be done with far fewer space platforms with out the need of solid shades.

The use of lasers could be the answer. A laser light in space can shine on to infinity. Small solar powered laser platforms positioned in space slowly rotated and releasing a some sort of plasma gas (fog) this would form a thin disc many miles in diameter, a coloured Laser would be then switched on forming a sheet of light ( Similar to those seen at rock concert displays through dry ice) this would illuminate the discs of plasma. Having several layers of various coloured lasers would darken the colour of  the disc thus blocking a percentage of light from the Sun. Putting the platforms one in front of the other would further darken the effect. Solar wind would eventually blow away the plasma, so the platforms would need replenished from time to time or just replaced.

The area covered with just a hand full of platforms would be vast. Not needing any new out of reach technology, and relatively small low powered cheap lasers.
« Last Edit: 02/01/2012 09:20 PM by Da5id »

Offline go4mars

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Re: Sun Shade concepts for Venus
« Reply #59 on: 01/30/2012 12:49 PM »
The use of lasers could be the answer. A laser light in space can shine on to infinity. Small solar powered laser platforms positioned in space slowly rotated and releasing a some sort of plasma gas (fog) this would form a thin disc many miles in diameter, a coloured Laser would be then switched on forming a sheet of light ( Similar to those seen at rock concert displays through dry ice) this would illuminate the disc of plasma. Having several layers of various coloured lasers would darken the colour of  the disc thus blocking a percentage of light from the Sun. Putting the platforms one in front of the other would further darken the effect. Solar wind would eventually blow away the plasma, so the platforms would need replenished from time to time or just replaced.

The area covered with just a hand full of platforms would be vast. Not needing any new out of reach technology, and relatively small low powered cheap lasers.
Although I generally am in favour of anything related to lasers, because they are cool, I'm not sure I followed you there.  For example, how does a laser release fog?  You want a fog in space to block some of the sunlight? 
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