Author Topic: Sun Shade concepts for Venus  (Read 41826 times)

Offline AlexCam

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Sun Shade concepts for Venus
« on: 09/10/2011 04:12 PM »
I know that all those large scale sun shade concepts for Earth that were floating around have turned out to be impracticable to implement or just to damn expensive. But what about Venus?

I wonder whether there are alternative ways to cooling Venus which use the sun shade concept, but use novel ideas. I have seen proposals for orbital sun shades around Venus, but those don't really are any easier to implement than a stationary Venus-Sun L-point based flat sun shade.

There are concepts that talk about seeding the Venusian atmosphere with genetically modified algae, principally that was proposed to modify the atmosphere. But what about injecting substances (organic or other) into the upper atmosphere that can build up some kind of reflective layer using atmospheric particles as building blocks that can effectively shade sunlight? Such a floating "dimming layer" might just be a cheap solution to cooling Venus to the point where CO2 ice forms and only a 3-4 bar atmosphere remains that is mostly nitrogen (bearable for humans at surface altitudes with breathing equipment).

Even more so, if this layer could be controlled it could simulate a 24 hour day cycle at some point in the future.

Offline aquanaut99

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Re: Sun Shade concepts for Venus
« Reply #1 on: 09/10/2011 04:16 PM »
Erm, if sun shade concepts for Earth are impracticable or too expensive, what makes you think they will be cheaper on Venus???

What am I missing here...

Offline AlexCam

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Re: Sun Shade concepts for Venus
« Reply #2 on: 09/10/2011 04:27 PM »
Erm, if sun shade concepts for Earth are impracticable or too expensive, what makes you think they will be cheaper on Venus???

What am I missing here...

Earth's atmosphere is 1 bar, Venus' atmosphere is 93 bar.

And we can (and are) shading the sun on Earth already (see Global Dimming), however it's pretty unlikely anyone would propose a radical concept of releasing lots of aerosols into the Earth's atmosphere to experiment with atmospheric sun shading to combat global warming.

I probably should have been clearer, BOTH sun shades for Earth and Venus which are space based are impracticable and too expensive. That's why I asked about new, different sun shade concept for Venus that use the specific properties of the Venusian atmosphere.

Offline aquanaut99

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Re: Sun Shade concepts for Venus
« Reply #3 on: 09/10/2011 04:40 PM »
Earth's atmosphere is 1 bar, Venus' atmosphere is 93 bar.

And we can (and are) shading the sun on Earth already (see Global Dimming), however it's pretty unlikely anyone would propose a radical concept of releasing lots of aerosols into the Earth's atmosphere to experiment with atmospheric sun shading to combat global warming.

I probably should have been clearer, BOTH sun shades for Earth and Venus which are space based are impracticable and too expensive. That's why I asked about new, different sun shade concept for Venus that use the specific properties of the Venusian atmosphere.

Ah ok, now I understand.

BTW, you're wrong about intentional aerosol release to combat global warming, it HAS been proposed. Problem is, it would only work if we keep it up for ever...

Offline Hop_David

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Re: Sun Shade concepts for Venus
« Reply #4 on: 09/10/2011 04:50 PM »
I know that all those large scale sun shade concepts for Earth that were floating around have turned out to be impracticable to implement or just to damn expensive. But what about Venus?

I wonder whether there are alternative ways to cooling Venus which use the sun shade concept, but use novel ideas. I have seen proposals for orbital sun shades around Venus, but those don't really are any easier to implement than a stationary Venus-Sun L-point based flat sun shade.

There are concepts that talk about seeding the Venusian atmosphere with genetically modified algae, principally that was proposed to modify the atmosphere. But what about injecting substances (organic or other) into the upper atmosphere that can build up some kind of reflective layer using atmospheric particles as building blocks that can effectively shade sunlight? Such a floating "dimming layer" might just be a cheap solution to cooling Venus to the point where CO2 ice forms and only a 3-4 bar atmosphere remains that is mostly nitrogen (bearable for humans at surface altitudes with breathing equipment).

Even more so, if this layer could be controlled it could simulate a 24 hour day cycle at some point in the future.

Recently Isaac Kuo posted this pdf which lays out a plan to capture an asteroid by exploiting 3 body interactions.

The talk about the comet Oterma which moves back and forth through Jupiters' realm as it moves between the sun's realm and exterior realm.



Baoyin et al look for an asteroid that drifts by sun earth L1 and L2 necks much as Oterma drifts by the Sun Jupiter L1 and L2 necks. With relatively little delta V (.4 km/sec) they propose to catch an asteroid near the boundaries of earth's sphere of influence.

For shading Venus, I would look for an asteroid that drifts by the Sun-Venus L1 or L2 necks and nudge this body into a halo orbit about Sun-Venus L1. After the asteroid is parked at SVL1, start disassembly to make a shade.

This is all science fiction, mind you.

Offline N45deg

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Re: Sun Shade concepts for Venus
« Reply #5 on: 09/11/2011 12:43 AM »
Recently Isaac Kuo posted this pdf which lays out a plan to capture an asteroid by exploiting 3 body interactions.

The talk about the comet Oterma which moves back and forth through Jupiters' realm as it moves between the sun's realm and exterior realm.



Baoyin et al look for an asteroid that drifts by sun earth L1 and L2 necks much as Oterma drifts by the Sun Jupiter L1 and L2 necks. With relatively little delta V (.4 km/sec) they propose to catch an asteroid near the boundaries of earth's sphere of influence.

For shading Venus, I would look for an asteroid that drifts by the Sun-Venus L1 or L2 necks and nudge this body into a halo orbit about Sun-Venus L1. After the asteroid is parked at SVL1, start disassembly to make a shade.

This is all science fiction, mind you.
[/quote]Why not just send your science fiction asteroid directly to impact Venus. Instant cooling effect with a smaller asteroid and then start the the science fictional mass rocket launches to populate. javascript:void(0);

Offline Moe Grills

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Re: Sun Shade concepts for Venus
« Reply #6 on: 09/16/2011 01:08 AM »
I know that all those large scale sun shade concepts for Earth that were floating around have turned out to be impracticable to implement or just to damn expensive. But what about Venus?

   Aha! I know what you're getting at!
Terraforming Venus, right?

Problems with idea?

Yes, lots.
 Let's start with financing.
Terraforming will cost trillions & trillions of dollars.
More money than available & in circulation in the United States today.

Second: Reducing sunlight on Venus will cool its atmosphere down somewhat; but it still will have an atmosphere with a pressure strong enough to crush a Brinks armored car like an empty beer can.
How are you going to eliminate most of the venusian atmosphere
to reduce pressure at its surface to tolerable levels?

And then there's carbon dioxide...way too much carbon dioxide.
You can use genetically modified bacteria to convert the CO2 into O2;
But then an atmosphere of high-pressure enriched oxygen will be
very corrosive.
 You need billions of trillions of tons of nitrogen to dillute the
(hypothetically)  enriched oxygen atmosphere.
Where are you going to get the huge quantities of nitrogen for the planet?

And Venus has no magnetic field.
How are you going to create a planetary magnetic field there?

And Venus takes 243 days to rotate on its axis.
How are you going to speed up the rotation 100-200 times?

I'm not being sarcastic, nor am I being blasphemous nor profane when I say that you are
trying to tackle a planetary scale problem without Godlike powers. 

« Last Edit: 09/16/2011 01:15 AM by Moe Grills »

Offline Andrew_W

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Re: Sun Shade concepts for Venus
« Reply #7 on: 09/16/2011 10:35 AM »

Problems with idea?

Yes, lots.
 Let's start with financing.
Terraforming will cost trillions & trillions of dollars.
More money than available & in circulation in the United States today.

Well it's something that's only worth considering for the future, under different economic and technological circumstances, todays global economy is substantially larger than that of 1911, who knows what the wealth and technology of 2111 will make possible.

Quote
Second: Reducing sunlight on Venus will cool its atmosphere down somewhat; but it still will have an atmosphere with a pressure strong enough to crush a Brinks armored car like an empty beer can.
How are you going to eliminate most of the venusian atmosphere
to reduce pressure at its surface to tolerable levels?

And then there's carbon dioxide...way too much carbon dioxide.
You can use genetically modified bacteria to convert the CO2 into O2;
But then an atmosphere of high-pressure enriched oxygen will be
very corrosive.
 You need billions of trillions of tons of nitrogen to dillute the
(hypothetically)  enriched oxygen atmosphere.
Where are you going to get the huge quantities of nitrogen for the planet?

Freeze the CO2 out at a suitable location to form a mass like the Antarctic ice cap, all you're left with is an N2 atmosphere of around 3 bars pressure, and if necessary liquefy some of that in a crater on your CO2 ice cap.
The biggest challenges will be deflecting the comets needed to form seas and getting the atmospheric O2 levels up in an acceptable time frame
Quote
And Venus has no magnetic field.
How are you going to create a planetary magnetic field there?

Why do you need a magnetic field? You won't lose atmosphere that fast as a result of particle impacts, and the atmosphere itself will be adequate radiation protection for life on the surface.

Quote
And Venus takes 243 days to rotate on its axis.
How are you going to speed up the rotation 100-200 times?

If you can use space shields to block sunlight from the planet to cool it down quickly, you can use space mirrors to reflect sunlight to keep some parts of the surface in permanent shade (the CO2 ice cap), and have whatever length of day you want over the rest of the planet by blocking sunlight on the sun-ward side and reflecting sunlight onto the shadowed side (you could even have the whole planet on a synchronized day-night cycle so everyones in the same time zone). If you can't form an ozone layer because of the lack of magnetic field, you can have UV absorbent filters on such space Sun-shields and mirrors .
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Offline gospacex

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Re: Sun Shade concepts for Venus
« Reply #8 on: 09/16/2011 01:02 PM »
Quote
Second: Reducing sunlight on Venus will cool its atmosphere down somewhat; but it still will have an atmosphere with a pressure strong enough to crush a Brinks armored car like an empty beer can.
How are you going to eliminate most of the venusian atmosphere
to reduce pressure at its surface to tolerable levels?

And then there's carbon dioxide...way too much carbon dioxide.
You can use genetically modified bacteria to convert the CO2 into O2;
But then an atmosphere of high-pressure enriched oxygen will be
very corrosive.
 You need billions of trillions of tons of nitrogen to dillute the
(hypothetically)  enriched oxygen atmosphere.
Where are you going to get the huge quantities of nitrogen for the planet?

Freeze the CO2 out at a suitable location to form a mass like the Antarctic ice cap,

That'd be more like a kilometer-thick layer of solid CO2 over entire planet.

Even if you block the Sun completely, it will take centuries for all CO2 to freeze.

Online KelvinZero

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Re: Sun Shade concepts for Venus
« Reply #9 on: 09/16/2011 01:22 PM »
Quote
Second: Reducing sunlight on Venus will cool its atmosphere down somewhat; but it still will have an atmosphere with a pressure strong enough to crush a Brinks armored car like an empty beer can.
How are you going to eliminate most of the venusian atmosphere
to reduce pressure at its surface to tolerable levels?

And then there's carbon dioxide...way too much carbon dioxide.
You can use genetically modified bacteria to convert the CO2 into O2;
But then an atmosphere of high-pressure enriched oxygen will be
very corrosive.
 You need billions of trillions of tons of nitrogen to dillute the
(hypothetically)  enriched oxygen atmosphere.
Where are you going to get the huge quantities of nitrogen for the planet?

Freeze the CO2 out at a suitable location to form a mass like the Antarctic ice cap,

That'd be more like a kilometer-thick layer of solid CO2 over entire planet.

Even if you block the Sun completely, it will take centuries for all CO2 to freeze.

I wonder. I have heard that stated before I think based on actual data of how venus is now, but does Venus's atmosphere mix much in its current state? I thought it was sort of stagnant and slow moving at the bottom. The sort of dramatic cooling we are discussing, especially if focused, could probably create massive permanent storms sucking super hot atmosphere up from the depths. Was this taken into account?

Offline peter-b

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Re: Sun Shade concepts for Venus
« Reply #10 on: 09/16/2011 01:24 PM »
It seems to me that lowering Venus' surface temperature would be far far easier than the next step: introducing the gigatonnes of hydrogen needed to fix its atmosphere's elemental balance.  :(

(This is the way to reduce atmospheric pressure, BTW; carbon sequestration by limestone formation on a geological timescale, coupled with conversion of atmospheric oxygen into water by the addition of hydrogen to the atmosphere).

As far as adding angular momentum to the planet, I've got no idea. Wrap superconducting coils around the planet and spin up using a drive current and the sun's magnetic field? You'd need to strip-mine a few NVOs to get the materials, of course...

Anyway, this seems like a reasonable engineering project, given a suitable timescale (200,000 years) and budget for getting it going (a significant proportion of Earth's Gross Planetary Product).
Research Scientist (Sensors), Sharp Laboratories of Europe, UK

Offline go4mars

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Re: Sun Shade concepts for Venus
« Reply #11 on: 09/16/2011 02:45 PM »
I read somewhere that within the upper atmosphere of Venus there is a fairly stable temperature band that is habitable.  I think the first Venusian colonists will be living in buoyant constructs within that zone.  On a much, much longer scale, perhaps extreme genetic manipulation, tremendous-scale removal of atmospheric gases, or both, or some other distant solution will allow us to live at Venus surface conditions, but I don't see sunshades as the enabler, and don't predict to witness a humans on Venus mission during my lifetime (or my grandkids).         
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Offline baldusi

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Re: Sun Shade concepts for Venus
« Reply #12 on: 09/16/2011 03:33 PM »
Wouldn't an angled impact of asteroids along the equator transmit some rotational momentum? It would also heat more than the hell that already is. I've heard someone saying that Venus lacks tectonics because it's greenhouse effect kept the surface to hot, that it actually acted as a heat pipe of the internal temperature to the surface, and thus radiated it much faster.
If that is so, is the interior of Venus solid? If it were still liquid, and you assume that some heat would still be crated by the radioactive decay of heavy elements in the core, and you could sort of lower the temperature of the surface rapidly while imparting rotational momentum (i.e. asteroid bombardment), couldn't you start some dynamo effect, with the core almost not rotating and the surface doing it?

Offline Hop_David

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Re: Sun Shade concepts for Venus
« Reply #13 on: 09/16/2011 03:43 PM »
I read somewhere that within the upper atmosphere of Venus there is a fairly stable temperature band that is habitable.     

Geoffrey Landis has written several papers on this as well as a few science fiction stories.

While comfortable temperatures and pressures exist at certain Venusian altitudes, the air is toxic and corrosive. Colonists in floating cloud cities would not have access to the surface. Therefore no metal mines for the Venusian civilization.

Earth-Venusian synodic period is very close to 8/5 years. Period of an earth-Venus Hohmann orbit is very close to 4/5 years. This makes a very nice cycler system possible. The cyclers earth fly by points would form a giant pentagram. This Venus cycler system is far more elegant than the proposed Mars Cycler schemes (Aldrin's and Niehoff's).

Offline go4mars

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Re: Sun Shade concepts for Venus
« Reply #14 on: 09/16/2011 04:27 PM »
Geoffrey Landis has written several papers on this as well as a few science fiction stories.
Thanks for that!

While comfortable temperatures and pressures exist at certain Venusian altitudes, the air is toxic and corrosive. Colonists in floating cloud cities would not have access to the surface. Therefore no metal mines for the Venusian civilization.

Stainless steel robotic/teleoperated blimp/submarines could have access to the surface. 

A series of these could even be lined up at different altitudes, designed with different buoyancy ranges, with cables going from one to the next (passing metals/ores up from one to the next sky-crane until they are at the floating colony)  They don't even need to be attached to eachother.  Just lower the hook down to the overweighted one below (which pulls the stations toward eachother until their offsetting buoyancies allow a break in contact and the load reels up to the next blimp station up.

Eventually might even have refridgeration ships to keep people cool inside using floating,buoyant broadcast powerstations which use atmospheric phenomena as an energy source.  The future is LARGE!
« Last Edit: 09/16/2011 04:29 PM by go4mars »
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Offline douglas100

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Re: Sun Shade concepts for Venus
« Reply #15 on: 09/16/2011 04:48 PM »
peter-b has got it about right. The resources and techniques needed to alter Venus to make it habitable would tax the most advanced spacefaring civilization, never mind little old 21st Century Earth.

This thread is an interesting theoretical discussion but I don't think such a thing will ever be attempted, even in the far future, not even when the means to do it exist. There is no reason to do so. You don't have to terraform any planet to support a large human population in space: O'Neill style habitats would be many orders of magnitude cheaper and can have the environment tailored to the needs of the population.
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Offline AlexCam

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Re: Sun Shade concepts for Venus
« Reply #16 on: 09/16/2011 06:20 PM »
peter-b has got it about right. The resources and techniques needed to alter Venus to make it habitable would tax the most advanced spacefaring civilization, never mind little old 21st Century Earth.

This thread is an interesting theoretical discussion but I don't think such a thing will ever be attempted, even in the far future, not even when the means to do it exist. There is no reason to do so. You don't have to terraform any planet to support a large human population in space: O'Neill style habitats would be many orders of magnitude cheaper and can have the environment tailored to the needs of the population.

I doubt you can support millions or billions of people in space in the future. Just too complicated. In contrast, Venus is basically Earth's twin sister planet and creative concepts can help with it becoming a more Earth like habitat.

At the end it is the sun shade that makes or breaks the concept of colonizing Venus. As it was said above, if you cool Venus through a sun shade over several decade (according to some estimates over 200 years), CO2 will freeze out of the atmosphere. That leaves a mostly nitrogen atmosphere with just about 3 bar. Something that allows humans to operate on the surface without protective suits, just oxygen masks. The sun shade could simulate a 24 hour daylight-night cycle.

That leaves us with how we can create a sun-shade without breaking the bank. A sun shade in space will likely break the bank. What I had in mind is something like "intelligent aerosols" in the Venusian atmosphere that are self-replicating and shade the planet. Aerosols that can stay in the upper atmosphere for the long-term and can be manipulated to either let light through or block it. That doesn't break the bank, if it could be done, it wouldn't cost more than any other current unmanned spaceflight mission. Of course we would need to wait quite a while for the temperatures to fall, but hey, it would be worth it!

Offline aquanaut99

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Re: Sun Shade concepts for Venus
« Reply #17 on: 09/16/2011 06:27 PM »
Terraforming Venus would be a challenge even for an ultra-advanced civilization. It would also be a waste of time and resources, since enven an Earth-like terraformed Venus would become uninhabitable due to solar brightening long before Earth itself.

Mars is a far better choice. And in the very long term, Titan is probably the place we should go to if we have to stay in our Solar System; it will be nice and cozy (smack in the middle of the habitable zone) when our Sun turns into a red giant...

Offline Andrew_W

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Re: Sun Shade concepts for Venus
« Reply #18 on: 09/16/2011 08:48 PM »
When I fired this sunshade idea at Adam Crowl his maths suggested the atmosphere taking between 2 and 90 years to freeze out with a geometric mean of ~13 years. Not a very long wait for that much real estate.

A sunshade at the Venus-Sun L1 point would need to have an area of around 500 million km^2 to shade the whole planet, made from solar sail cloth at 10g/m^2 it would mass 5 billion tonnes, a huge mass compared to what we put into space now, not that much compared to what we move around on the surface of the Earth each year, so for a space based civilization I don't think such a sunshade would "break the bank"

Dry Ice has a density of 1.6g/cc, at the moment there's CO2 the equivalent of 650 meters of dry ice over the entire surface of Venus, how thick can you make an ice sheet? Well the average thickness of the Antarctic ice is 2,000 m, and the greatest measured thickness is more than 4,750 m, if we could get the average thickness of a Venusian CO2 ice sheet up to 6.5km it would cover 10% of the planet, leaving nearly 400 million km^2 uncovered.

My not great maths suggests that the momentum of the mass of the comets necessary to provide Venus with shallow seas would not be enough to change the rate of rotation by more than around 10 m/s, so you could maybe change it so only one face is towards the Sun, if there's any advantage in that, but not change it by enough to get anything like a 24 hour day.

Last I heard the theory is that Venus does not have plate tectonics, it's surface undergoes periodic reforming through massive volcanic events - a bit like as in the John Cusack movie "2012" - this could be a problem for terraforming that planet.
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Online KelvinZero

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Re: Sun Shade concepts for Venus
« Reply #19 on: 09/16/2011 10:14 PM »
I doubt you can support millions or billions of people in space in the future. Just too complicated. In contrast, Venus is basically Earth's twin sister planet and creative concepts can help with it becoming a more Earth like habitat.

At the end it is the sun shade that makes or breaks the concept of colonizing Venus. As it was said above, if you cool Venus through a sun shade over several decade (according to some estimates over 200 years), CO2 will freeze out of the atmosphere. That leaves a mostly nitrogen atmosphere with just about 3 bar. Something that allows humans to operate on the surface without protective suits, just oxygen masks. The sun shade could simulate a 24 hour daylight-night cycle.

That leaves us with how we can create a sun-shade without breaking the bank. A sun shade in space will likely break the bank. What I had in mind is something like "intelligent aerosols" in the Venusian atmosphere that are self-replicating and shade the planet. Aerosols that can stay in the upper atmosphere for the long-term and can be manipulated to either let light through or block it. That doesn't break the bank, if it could be done, it wouldn't cost more than any other current unmanned spaceflight mission. Of course we would need to wait quite a while for the temperatures to fall, but hey, it would be worth it!
There is very little hydrogen on venus which makes engineering an earth lifeform for it problematic.
My favorite scheme is self replicating little reflective solar sails that have very basic 'flocking' ability. With something like that you could regulate the light to any part of the planet, even fake a 24 hour day with sunrise and sunset.

When people say it will cost trillions, it really is undefined. Until we have self replicating somethings that can thrive in other environments than earth we really have no hope. Once we do the cost is somewhere between zero and "oops they just ate jupiter".

I personally think we will one day learn to live within the small icy bodies of the solar system and forget why we ever thought the ability to stand on the 25% of earth which is not ocean was so important to us.

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