Terraforming Venus

[Moontanman]

Originally Posted by Boerseun

Haven't read all replies, so excuse me if I repeat a point:

Terraforming Venus is a useless effort. Whether it can me done mechanically or biologically, won't help at all.

And it's all about Venus' rotation period.

Say you get the atmosphere to simulate Earth's, a nice and homely nitrogen/oxygen atmosphere befitting us two-legged beasts of pollution.

Won't help.

And simply 'cause however nice you make the atmosphere, a day lasting in excess of a hundred Earth days will make the one side unbearably hot for months on end, and the other side frozen over.

No plants can survive conditions like that (save some very extreme extremophiles, I guess). And, no plants, no agriculture, no humans.

If you've got the atmopshere sorted, you're gonna have to speed that ball of rock up some. By quite a bit. So, forget Venus, in my honest, albeit a bit negative, though thoroughly realistic, opinion.

Actually speeding up the rotation of Venus might be easier than modifying the atmosphere. All you have to do is use small asteriods as gravity tractors. sling a few asteriods a few thousands of times and you could speed up the rotation, even move Venus away from the sun. Several authors have suggested moving the Earth away from the sun using this method when the sun begins to expnd in it's old age, or sooner as the sun gets slowly brighter over time. Probably take less time than modifying the atmosphere of Venus for sure!

SPACE.com -- Recipe for Saving Earth: Move It

Nasa aims to move Earth | Environment | The Observer

BBC News | SCI/TECH | Planet Earth on the move

[Ahmabeliever]

I think there is a chicken - egg scenario here.

Where life is needed to assist terraforming
And terraforming is needed to support life.

[Moontanman]

Originally Posted by Ahmabeliever

I think there is a chicken - egg scenario here.

Where life is needed to assist terraforming
And terraforming is needed to support life.

Depends on what you mean by life, if you are talking about redwoods and whales then you have a good point but it doesn't take near as much to make an environment ready for extremeophiles and then they slowly get it ready for less tough bacteria then on to even more fragile bacteria and on to cyanobacteria to an oxygen atmosphere then to even more complex organisms and after a very long time if you are very patient you can have your redwoods and whales. Not a chicken and a egg but definitely lizard to a chicken type problem. The good news is that life does indeed moderate the biosphere through various feed back mechanisms. On Venus the job would be getting the environment to the point that these mechanisms could take over. If it was me I'd want to move the planet away from the sun quite a bit at least before I even tried to introduce life or anything else. The bad news is the way Venus is now the best you could hope for would be thermopile type bacteria like you would find in hot springs. Some of these bacteria can produce oxygen but most oxygen producers would like a cooler climate. If Venus hadn't been messed up to start with by giant impactors "maybe" life could have kept it at a low enough temp for complex life to evolve but it would be much different than what we know. On Earth the limit for complex life is around 45 degrees C. Higher than that, all you get on Earth is bacteria. Under pressure there is reason to believe at least bacteria can thrive at temps up to about 300 degrees C. (Thomas Gold) Mars would be an easier case study for sure. Much easier to heat up than it is to cool down from a standpoint of energy. Think of heating a home vs cooling one. Where I live it is so hot and humid most of the year almost everyone has some sort of AC system but it costs a lot to run it. But in the winter costs go down because it's easier to heat than cool. Venus would be a very hard nut to crack and getting harder as time goes by. Maybe we could place Venus at the orbit of Mars and place Mars in the orbit of Venus. Not with current technology but who knows what we will be able to do 200 years from now. Look back 200 years to see the possibilities.

[Ahmabeliever]

Agreed on the heating/cooling issue, I do a lot of work with fish and cooling is an expensive nightmare, heating is very easy.

What Venus does have is a ridiculous amount of solar energy. Should we ever get there a power supply is a given.

There is also the solar wind. Now, it's beyond me, but I'm sure someone out there is smart enough to figure out how we might harness these power supplies to increase the planets rotation.

Using the existing rotation to build upon perhaps the temperature difference between day and night might also be utilised to create a vacuum-expulsion type scenario filtering the atmosphere as it does this. Unwanted elements out and wanted elements back in till the required ratios are met???

Fascinating subject just a bit out of my league.

[Moontanman]

Originally Posted by Ahmabeliever

Agreed on the heating/cooling issue, I do a lot of work with fish and cooling is an expensive nightmare, heating is very easy.

What Venus does have is a ridiculous amount of solar energy. Should we ever get there a power supply is a given.

There is also the solar wind. Now, it's beyond me, but I'm sure someone out there is smart enough to figure out how we might harness these power supplies to increase the planets rotation.

Using the existing rotation to build upon perhaps the temperature difference between day and night might also be utilised to create a vacuum-expulsion type scenario filtering the atmosphere as it does this. Unwanted elements out and wanted elements back in till the required ratios are met???

Fascinating subject just a bit out of my league.

Realistically the planet will have to be moved and if we could do that then why not modify the entire inner solar system? Move Mars to the orbit of Venus, move Venus to the orbit of Mars. then move Ceres into orbit around Mars, speed up the rotation of Mars a little bit to make the core more active or maybe even merge Mercury with Mars to make a new slightly larger planet. Speed up the rotation of Venus, move Jupiter's moon IO into orbit around Venus. There is reason to believe a large moon is need for long term viability of a planet. Bring water to both Mars and Venus at some point. Then as the Sun warms up slowly move all three inner planets left away from the sun! Maybe by then we can figure out how to travel from star to star in a reasonable length of time! Or learn to make orbital habitats and leave the planets to go wild, three planets with wild ecosystems! Oh how the big, the Ego of Man! Maybe these immense projects will keep us to busy to want to kill each other!

[Boerseun]

Moving planets around like the last couple of posts propose, is so far beyond our current capabilities that it can be discounted and disqualified as completely impossible for at least thousands of years.

So - are we discussing the realistic possibilities of terraforming Venus, or are we engaging in whimsical speculation?

[CraigD]

Originally Posted by Moontanman

Realistically the planet will have to be moved and if we could do that then why not modify the entire inner solar system? Move Mars to the orbit of Venus, move Venus to the orbit of Mars. …

The primary effect changing the radius of the nearly-circular orbit of a Venus or Mars has on the planet is changing its solar power, as the inverse square of the orbital radius. Moving Venus (current radius 0.72 AU) to the orbit of Mars (1.38 AU) changes its solar power to times its current value.

From what I gather from the various sources referenced in this thread, Venus only needs to have its solar power reduced to about 0.8 its present value to have the potential (once you sorted out its atmospheric “troubles” ) of being its former, Earth-like self, which would require “only” a move from its present 0.72 AU to 0.805 AU.

However, if you make some rough engineering estimates of the masses and energies involved in moving a planet, I think it becomes clear that moving Venus is an extravagant approach to reducing their solar power, and far, far less practical than any of a number of schemes, such as shading it and/or reducing its greenhouse and surface solar power absorptions rate.

Moving planets, however, is hugely energy expensive. Here are a some illustrations:

To move Venus from a circular orbit at 0.72 to 1.38 AU in a single orbital year requires an periapsis change in velocity (delta-v) of 5132.5 m/s, and an apoapsis delta-v of 4352.9 m/s, for a total change in kinetic energy of about . This is about 230,000,000,000 times the present-day annual energy consumption of human kind, 20,000,000 times the annual solar energy input of Earth, and 3.3 days of the total energy output of the Sun! These figures don’t take into account the energy inefficiencies of whatever engine would be required to actually make such a move, so are likely much understated.

Moving it a shorter distance – say, to 0.8 AU – reduces the energy by about a factor of 28.

A slower move, accomplished by a series of smaller transfer orbits, can bring the power requirements down to something feasible for a reasonably imaginable 21st-or-so century human civilization. Here’s an example:

Assume we can build a really big mass-driver (AKA a cannon) on Venus. Make it 100,000 m long, and capable of accelerating to solar escape velocity (617700 m/s), and it would be able to make the move in about 1,000,000 years, requiring a minimum power of about . is about 16,000,000 times the current rate of terrestrial coal mining, while is about 6,500,000 times the current power produced by human kind, and 560 times the solar power received by Earth, and 1/4,000,000th of the total power of the Sun, or the output of a super-efficient space-based solar array with about 300 times the area of the cross-section of Venus (about ). The total mass expended from Venus would be , about 0.3% of its total.

So a super-efficient space cannon with a capacity of 16 million times the current world coal production powered by a solar array 300 times larger than Venus could move it to a more hospitable orbital radius of .8 AU in a million years,
or
a shade 1/1000th the size of this solar power array could have the same effect while leaving it in its present orbit.

All the data and formulas needed to reproduce the above can be found at the wikipedia pages “Venus”, “Mars”, “Transfer Orbit”, “Orders of magnitude (energy)”, “Orders of magnitude (power)”, and “Coal”.

[Moontanman]

Originally Posted by Boerseun

Moving planets around like the last couple of posts propose, is so far beyond our current capabilities that it can be discounted and disqualified as completely impossible for at least thousands of years.

So - are we discussing the realistic possibilities of terraforming Venus, or are we engaging in whimsical speculation?

Did you read my post number 21? Moving a planet is very close to being within our current technology, in 200 years it should be very much easier. Look at our tecnology 200 years ago and look at where we are now. I don't think it's unlikely we will be able to rearrange the inner solar sytem to our own desires at some point if we can agree on what to do. The disagreement on what we should do will be a greater obstical than what we could do.

[CraigD]

Originally Posted by Boerseun

Moving planets around like the last couple of posts propose, is so far beyond our current capabilities that it can be discounted and disqualified as completely impossible for at least thousands of years.

So - are we discussing the realistic possibilities of terraforming Venus, or are we engaging in whimsical speculation?

Originally Posted by Moontanman

Did you read my post number 21? Moving a planet is very close to being within our current technology, in 200 years it should be very much easier.

I think it’s critical to look at the numbers involved in proposals such as Adams, Laughlin, and Peiser’s, and note the very long durations of these proposed engineering projects.

As the space.com article details, this proposal involves precisely adjusting the orbit of a fairly large (100 km diameter) Kuiper belt object so that it makes a 16,000 km pass in front of the Earth every 6,000 years. This would give Earth (or, for practical purposes, Mars or Venus) a delta-V of about 0.0000877 m/s with each pass, about 1/7th the 6-month delta-V of my giant solar-powered space cannon scheme. It takes two passes, one at aphelion, another at perihelion, to increase the target planet’s orbit by about 0.0000000118 AU while keeping it roughly circular, so a 0.72 to .8 AU trip like I described, which takes about 1 million years with the giant space cannon engine, takes about 81 billion with a single large KBO.

A million years is a long project timeline by human standards. 81 billion is long by the standards of stars – the Sun only has about 5 billion years before its red giant phase, which will throw all terraforming calculations into a wildly different domain.

Gravity tugging solutions like this are, though, elegant, and can be scaled up by using more KBOs. Though they’ve not all been observed yet, astronomy currently predicts about 17,000 KBOs 100 km or greater in diameter exist. Using a “mere” 6,000 of them would bring a .08 AU planet move down to a “mere” 14 million year timeline. A really audacious engineer might devise a plan to bring bigger bodies into play – using a couple of Pluto-size KBOs would speed it up by a factor of about 50,000 vs. a single 100 km one, making the 0.72 to .8 AU transfer in a mere 1.6 million years, and Earth-to-Mars orbit transfer less that 7 million.

Equivalent terraforming solutions, such as space-based sun shades, could be made on much shorter timelines of centuries or even decades.

Originally Posted by Moontanman

I don't think it's unlikely we will be able to rearrange the inner solar sytem to our own desires at some point if we can agree on what to do. The disagreement on what we should do will be a greater obstical than what we could do.

While I share Moontanman’s optimism about future human engineering ability, I don’t think it likely that we’ll do much planet arranging.

In addition to the time issues discussed above, I strongly suspect that by the time humans have the technology necessary to move planets, we’ll have outgrown the use of them other than as stocks of raw materials. Well-made artificial worlds, I think, promise to be vastly more practical solutions to the “where to live” problem than moving and terraforming planets, and when faced with what to do with a planet-size mass of useful matter that can be made into artificial worlds able to support hundreds of trillions vs. mere tens or hundreds of billions in their raw form, I suspect this disparity in efficiency will overpower nostalgia for downward curving horizons and high skys.

When future conservationists argue for saving the Planet earth, they may well be arguing literally against its disassembly for use as raw material.

[Moontanman]

Originally Posted by CraigD

I think it’s critical to look at the numbers involved in proposals such as Adams, Laughlin, and Peiser’s, and note the very long durations of these proposed engineering projects.

As the space.com article details, this proposal involves precisely adjusting the orbit of a fairly large (100 km diameter) Kuiper belt object so that it makes a 16,000 km pass in front of the Earth every 6,000 years. This would give Earth (or, for practical purposes, Mars or Venus) a delta-V of about 0.0000877 m/s with each pass, about 1/7th the 6-month delta-V of my giant solar-powered space cannon scheme. It takes two passes, one at aphelion, another at perihelion, to increase the target planet’s orbit by about 0.0000000118 AU while keeping it roughly circular, so a 0.72 to .8 AU trip like I described, which takes about 1 million years with the giant space cannon engine, takes about 81 billion with a single large KBO.

A million years is a long project timeline by human standards. 81 billion is long by the standards of stars – the Sun only has about 5 billion years before its red giant phase, which will throw all terraforming calculations into a wildly different domain.

Gravity tugging solutions like this are, though, elegant, and can be scaled up by using more KBOs. Though they’ve not all been observed yet, astronomy currently predicts about 17,000 KBOs 100 km or greater in diameter exist. Using a “mere” 6,000 of them would bring a .08 AU planet move down to a “mere” 14 million year timeline. A really audacious engineer might devise a plan to bring bigger bodies into play – using a couple of Pluto-size KBOs would speed it up by a factor of about 50,000 vs. a single 100 km one, making the 0.72 to .8 AU transfer in a mere 1.6 million years, and Earth-to-Mars orbit transfer less that 7 million.

Equivalent terraforming solutions, such as space-based sun shades, could be made on much shorter timelines of centuries or even decades.While I share Moontanman’s optimism about future human engineering ability, I don’t think it likely that we’ll do much planet arranging.

In addition to the time issues discussed above, I strongly suspect that by the time humans have the technology necessary to move planets, we’ll have outgrown the use of them other than as stocks of raw materials. Well-made artificial worlds, I think, promise to be vastly more practical solutions to the “where to live” problem than moving and terraforming planets, and when faced with what to do with a planet-size mass of useful matter that can be made into artificial worlds able to support hundreds of trillions vs. mere tens or hundreds of billions in their raw form, I suspect this disparity in efficiency will overpower nostalgia for downward curving horizons and high skys.

When future conservationists argue for saving the Planet earth, they may well be arguing literally against its disassembly for use as raw material.

Actually I have to admit that personally I agree that planets will become obsolete before we get around to worring about moving them. I was trying to concentrate on the aspect of terra forming a planet and what it entail than I was to being really practical about it. If a way was found to remain healthy with out gravity then even asteriods become possible habitats. If not them either can shaped or toroidal shaped colonies become a must. In my mind I can see toroidal shaped colonies possibly very big in the 600 miles across and 200 miles thick range rotating fast enough to make the inside surface as close to one gravity as is nesesarry for human health. The less gravity nesesarry the bigger the colony could be. combine that with magnetic sails and a thick skin of possibly continous carbon tubes and ice you could move even a very large obect around the solar system, maybe even to the stars. Details don't have anything to do with terra forming but it's really the most practical way to colonise space long term.