[Crazy] Venus and Planetary-scale engines?

[Dartz]

A question the Venus terraforming program must solve.

How to accelerate the planet's rotation so it has a proper day-night cycle, and how to reduce the crushing concentrations of carbon-dioxide and toxic gasses.

And here I'm wondering, why not kill two birds with one stone? Teratons of gas will make for excellent remass - you just need engines big enough to accelerate it to escape velocity.

Proper angling of the thrust from these world engines could be used to accelerate the rotation of the planet.

These things will be utterly Babylonian in scale - requiring terajoules of energy for decades at a time.

It might even be possible to move Venus to co-orbit with Earth. Okay, so that arrangement will result in a collision if a few million years but by then humanity will be long-gone, and in the short term the benefits in venusian habitability will be worth it. And sure, if we can move it, we can stabilise it.

Thoughts?

[robkelk]

Somebody's going to have to come up with a handwaved substance that can reliably stand up to the conditions of Venus for years at a time. Not impossible, but it'll have to be something more durable than what Crystal Osaka was built out of.

[Dartz]

We could build one - I mean, it's possible to passivate against the corrosive effects of the venusian atmosphere. A little like a space-lift with a massive power source at the top - a mix of power generators or a massive plate of solar panels.

Once properly anchored to the ground it's then a matter of using the generator power to ionise the atmospheric gasses and accelerate them to a useful velocity. A sort of planetary caterpillar drive.

There's probably some numbers you can put on it. But I wouldn't even know where to start.

Even using the solar panels themselves as a sort of massive optical turbine to assist.

Eventually you're going to get to the point where you're out of atmosphere, and need to use actual bedrock. And maybe reduce the moment of inertia of the planet. Could that be done with a ring of something? Like gate-metal or one of it's derivatives?

So that's what it feels like to loose sanity points.

It's a pleasant feeling.

That'd be some blue-hair day dumping this puppy out. Towers 20,000km tall - the planet whirling like a catherine's wheel of plasma. Or a massive planet-scale swastika. Did we just turn the planet of love and justice into a giant hate-symbol?

Maybe Dee could run the numbers and work out how fast those jets need to go. We just need to make it spin about 243 times faster.

I should lay off the weizen after work.

[nocarename]

Well, what are the odds that the atmosphere, more or less, stays in the same solar orbit that Venus has and gets recollected by the planetary gravity? I really do think you need to aim what you're throwing to keep it from being a problem again in a decade or two.

[Hivemind_Chan]

To spin up Venus to Earth- like solar cycle you need 1,6x10^29 joules or 50 billion petawatt hours. In 2013 Earth total power production is around 18 terawatt- hours per year. It should be theoretically possible to speed up Venus rotation by launching atmosphere out of mass drivers positioned at the equator and firing mass streams at the speed of around 10% c. At this speed gasses would escape into interstellar space since they would be moving above Sol escape velocity and thus they would not encounter Venus again. The thing is, you would be wasting precious gasses that could be used in other places such as terraformation of Mars. You can fire gasses at Mars that way as well killing two birds with one stone. Note that Venus has a lot of nitrogen which is irreplaceable for life and thus it is a very precious export gas. At the same time Mars has little nitrogen in its atmosphere (in total, not just proportionally) and thus it would have to import it to get an Earth- like atmosphere.

I think that the main issue particularly in fenspace setting is the scale. You would need hundreds of thousands to millions of titanic mass drivers lobbing carbon dioxide 24/7 into space for decades. This would be orders of magnitude bigger than anything ever built on and off Earth combined. A single mass driver like that would be an engineering marvel for current civilization, millions are beyond the “current” fenspace capabilities. The corrosive atmosphere effect on the structures with insane pressures can actually be handwaved away with special ‘wavium paint, it is not too far away from what it already allows.

It might be worth it to use a combined method along with hydrogen import. Venus almost completely lacks hydrogen so to get any water you need to import it, most likely by dropping huge comets. You can control comet arrival to impart rotation which can be combined with gas exports for maximum results, but it is still a matter of hundreds if not thousands of years.

[Dartz]

Well. Even if you want to capture some of it for Mars - 90-odd percent of it will still be waste CO2.

In truth, you don't even have to accelerate the planet to make it tolereable. Just flare the gas off and siphon enough off to stabilise the flare tower against the planet's spin, while supporting the solar arrays necessary to power the flares. Build them at the poles so they're always in sun, maybe? That's probably that *bit* less energy intensive. Along with the control comet-parking that seems to be happening on Mars to add the hydrogen.

It's a bit of a drunken idea.

I never really got how the broadleaf process on the wiki was supposed to work.

[Hivemind_Chan]

Well. Even if you want to capture some of it for Mars - 90-odd percent of it will still be waste CO2. 

In truth, you don't even have to accelerate the planet to make it tolereable. Just flare the gas off and siphon enough off to stabilise the flare tower against the planet's spin, while supporting the solar arrays necessary to power the flares. Build them at the poles so they're always in sun, maybe?  That's probably that *bit* less energy intensive. Along with the control comet-parking that seems to be happening on Mars to add the hydrogen.

It's a bit of a drunken idea.

I never really got how the broadleaf process on the wiki was supposed to work.

Well, first of all you can filter gas out of the atmosphere and fire it in a higher concentration or in a barrage of essentially pressurized cans. Also, Mars has less than 1% of Earth atmospheric pressure so it would still want to get lots of CO2 along with nitrogen. However, once again the main issue there is the energy. You need ridiculous quantity of solar panels, likely comparable to plating a large part of the planet in photovoltaics. It might make more sense to use huge fusion plants per every mass driver. We literally need billions of times the output of entire Earth from a population that numbers several million across entire fenspace. By the way, the reason for such high exhaust velocity is to have more or less decent ISP and thus efficiency per expelled mass of gas. If you go less you end up needing to expel more gas to reach same goal and if you go slower than Sol escape velocity you end up running into your own expelled gas eventually.

It would actually be easier with a gas giant since there is a concept of Fusion Candle which is essentially two fusion engines floating in the atmosphere, one pointing up and one pointing down. When you built hundreds of millions of them you can fly Jupiter like a spaceship, even if with terrible acceleration. It can't be used on Venus because its atmosphere doesn't consist out of fusion fuels.

[Rajvik]

i'm sure you are all familiar with the idea of a solar chimney, why not do something similar allowing Venus's own pressure to push the lower level gas up a chimney to the vacuum of space, just angle the exhaust to assist in speeding the rotation

[ckosacranoid]

Has anyone seen the planet, Venus? It was here last week.
OH CARP! It's looking at earth now and the Terrens are having a fit cause it ruins the view of Mars.
How and when the hell did the Fen move Venus into orbit to be seen from earth and the moon?