[FlamingCobra]

Moving this discussion from another thread..


We all know that Venus is a ****ing inferno. We all know that Venus most likely had liquid water at one time. And plate tectonics. And probably a carbon cycle too.

So what happened?

Here we discuss exactly this question.



If we look at Venus' atmosphere now, we find that it is nearly devoid of hydrogen; which should be present because Venus had water at one time. All the hydrogen has blown away because there is no natural magnetic field to hold it in place.

The question of why it doesn't have a magnetic field boils down to "Why doesn't Venus have a dynamo?"


Does the core not spin because Venus rotates too slowly, or does it have to do with something else? Like lunar tidal forces. Because Venus doesn't have a moon.

[Dragon]

We don't really know what causes the Earth to have it's magnetic field. There are speculations, but we don't know for sure. If we found out, that would have helped with explaining Venus.

[Unknown Target]

I actually developed this concept last year, supposing colonization efforts on Venus would result in floating cities. Mining would be done by blasting huge chunks of rock out of the planet and floating them up to the upper atmosphere. Resources would be easier to transport to and from space given that the conditions about 50 km up are actually quite favorable - 71 degrees F, 1 Earth atmosphere of pressure. If some sort of resistance to the sulfuric acid rain/clouds could be developed, it may be a viable option.

[TwentyPercentCooler]

Moving this discussion from another thread..


We all know that Venus is a ****ing inferno. We all know that Venus most likely had liquid water at one time. And plate tectonics. And probably a carbon cycle too.

So what happened?

Here we discuss exactly this question.



If we look at Venus' atmosphere now, we find that it is nearly devoid of hydrogen; which should be present because Venus had water at one time. All the hydrogen has blown away because there is no natural magnetic field to hold it in place.

The question of why it doesn't have a magnetic field boils down to "Why doesn't Venus have a dynamo?"


Does the core not spin because Venus rotates too slowly, or does it have to do with something else? Like lunar tidal forces. Because Venus doesn't have a moon.

It's likely that it rotates too slowly; or, it's also possibly that tidal forces from the sun could keep the liquid core, if it exists, tidally locked. Really, there's a lot of possible reasons Venus could be lacking a magnetic field. It seems to be rather rare for terrestrial planets to have strong magnetic fields capable of shielding them to the extent that ours does.

That being said, oddly enough, Venus could be our best hope for colonization. Structures supported by gas torus supports, floating on the incredibly dense atmosphere. We wouldn't have to worry about the long-term effects of microgravity on human physiology, and even though the colonies would be floating above the bulk of that atmosphere, they would still be protected from micrometeorite impacts or errant debris. It's kind of interesting to think about, at any rate.

[FlamingCobra]

We don't really know what causes the Earth to have it's magnetic field. There are speculations, but we don't know for sure. If we found out, that would have helped with explaining Venus.

So......... dynamo is "speculation"?


What if we somehow put Eris in orbit around Venus? It's not that much smaller than the moon. It would generate tidal forces. Would the tidal forces cause the core to spin?

If we caused planetoids from the Kuiper Belt (besides eris, which I think is rocky) to collide with venus, the impact could alter its rotation AND deliver large quantities of water to its surface, which could stay liquid if we cooled the planet with "sunshades" beforehand. Right?


Liquid water would make the crust viscous enough to subduct and BLAM! You have plate tectonics. with plate tectonics, BLAM, you have a carbon cycle. Right?

[Mars]

Moving things that size is a helluvalot of energy you know. . .

[MP-Ryan]

We don't really know what causes the Earth to have it's magnetic field. There are speculations, but we don't know for sure. If we found out, that would have helped with explaining Venus.

So......... dynamo is "speculation"?


What if we somehow put Eris in orbit around Venus? It's not that much smaller than the moon. It would generate tidal forces. Would the tidal forces cause the core to spin?

If we caused planetoids from the Kuiper Belt (besides eris, which I think is rocky) to collide with venus, the impact could alter its rotation AND deliver large quantities of water to its surface, which could stay liquid if we cooled the planet with "sunshades" beforehand. Right?


Liquid water would make the crust viscous enough to subduct and BLAM! You have plate tectonics. with plate tectonics, BLAM, you have a carbon cycle. Right?

I'm not quite sure what the point of this would be, even if it were possible.

[Unknown Target]

Terraforming, essentially.

[watsisname]

So......... dynamo is "speculation"?

Not really.  It certainly involves fluid convection in the earth's core, though as I understand it the exact details are still being worked out.  Not really my area of though.

What if we somehow put Eris in orbit around Venus?It's not that much smaller than the moon.  It would generate tidal forces. Would the tidal forces cause the core to spin?

The time required for it to have even a minute effect would be far longer than the remaining lifetime of our Sun, so unfortunately it'd be a futile exercise. :/

If we caused planetoids from the Kuiper Belt (besides eris, which I think is rocky) to collide with venus, the impact could alter its rotation AND deliver large quantities of water to its surface, which could stay liquid if we cooled the planet with "sunshades" beforehand. Right?

Changing the orbits of Kuiper Belt objects to bring them to a collision with Venus wouldn't require as much delta-v as changing the orbits of main belt 'roids, but you'd have to send something out to the Kuiper Belt in order to move them in the first place, which is expensive as all hell.

As for the change in Venus' rotation, that would require a LOT of asteroid impactors.  Really you'd need to hit Venus with a similar order-of-magnitude mass, so we're talking 1000km-diameter sized objects to do the job.  Not very practical...

Liquid water would make the crust viscous enough to subduct and BLAM! You have plate tectonics. with plate tectonics, BLAM, you have a carbon cycle. Right?

I'm not sure what liquid water would do for you there, plate tectonics is driven by thermal convection currents in the planet's mantle.

[Nohiki]

Well, because venus rotates the other way then all other lanets, one theory is that somehow, in the past, something turned Venus upside down. The only reasons i can think of that would cause this are series of massive earthquake (magnitudes 9+ are known to hamper with Earth's axis) or loss of a moon (according to sims, if Earth lost the moon, it would start rolling on it's orbit, making one hemisphere permanently day and the other night). About the hydrogen, it might have all just reacted and turn into acids.

[watsisname]

Don't think earthquakes would do it.  Earthquakes can indeed redistribute the planet's angular momentum around a bit, but the angular momentum as a whole has to be conserved, meaning an outside force is necessary to explain such retrograde rotation (either that or Venus just formed that way).  Most likely it was due to giant impacts early on in the solar system's history.  The same is hypothesized to explain the crazy tilt of Uranus' rotation axis.

[Bobboau]

About the hydrogen, it might have all just reacted and turn into acids.

you don't understand how chemistry works do you?

[FlamingCobra]

Terraforming, essentially.

Thank you

Well, because venus rotates the other way then all other lanets, one theory is that somehow, in the past, something turned Venus upside down. The only reasons i can think of that would cause this are series of massive earthquake (magnitudes 9+ are known to hamper with Earth's axis) or loss of a moon (according to sims, if Earth lost the moon, it would start rolling on it's orbit, making one hemisphere permanently day and the other night). About the hydrogen, it might have all just reacted and turn into acids.

This may explain Venus'  retrograde rotation
http://www.astronomycafe.net/qadir/q50.html

I'm not sure what liquid water would do for you there, plate tectonics is driven by thermal convection currents in the planet's mantle.

From Wikipedia: There is no evidence for plate tectonics, possibly because its crust is too strong to subduct without water to make it less viscous.

I also read somewhere that Earth's crust would not subduct without an ocean because of its size. If Earth were larger, its crust would be able to subduct without any liquid water at all.

[TwentyPercentCooler]

Terraforming would be insanely expensive, extremely time-consuming, and there's always the possibility that we could dump money and time into it without producing results. We know a lot of things, but manipulating an entire ecosystem on such a vast scale would basically be a shot in the dark. Floating platforms supported by gas toroids is probably our most realistic option for colonizing Venus, or almost any extraterrestrial body. The planet's slow rotation would mean nothing, and the temperature, pressure, and gravity would all be at normal levels. We would just need construction materials, resistant to sulfuric acid and suitable for forming load-bearing structures, that could be produced on a large scale. Given that materials science is one of the strong points of the human race, in my opinion, this shouldn't be too incredibly difficult.

[The E]

Yeah, but the big question would still be, "Why?"
I mean, I know about the appeal of doing stuff because they can be done, but I seriously have to ask myself why terraforming Venus should be a good idea when you could more easily colonize Luna or Mars.

[TwentyPercentCooler]

Yeah, but the big question would still be, "Why?"
I mean, I know about the appeal of doing stuff because they can be done, but I seriously have to ask myself why terraforming Venus should be a good idea when you could more easily colonize Luna or Mars.

That was kind of what I was wondering. Yeah, it would be a huge scientific leap or whatever, but if we screw it up it'll just be a massive waste of time and money.

That being said, Venus is still our best option - a base on the moon makes logistical sense, because constructing materials there and launching them from there would be a lot less expensive than doing it from Earth. But if we want to expand past that, Venus is a much better idea than Mars. Just without the terraforming.

[The E]

Umm.

Why? Because, way I see it, colonizing Mars represents a huge challenge, but it could actually be done using current technology. The same can not be said about Venus, not by a long shot. And still the question would be why, because as far as I can tell, the ressources that may be available on Venus are so inaccessible as to make retrieval somewhat challenging....

[TwentyPercentCooler]

Umm.

Why? Because, way I see it, colonizing Mars represents a huge challenge, but it could actually be done using current technology. The same can not be said about Venus, not by a long shot. And still the question would be why, because as far as I can tell, the ressources that may be available on Venus are so inaccessible as to make retrieval somewhat challenging....

I don't think it's a question of the technology as much as it is the difficulty. Mars has much more extreme temperatures, almost no atmosphere, and just a little over 1/3 g on the surface. We still really don't have any idea if humans can live in a low-gravity environment for the extended periods of time necessary for colonization efforts. We would have to protect the people living there not only from the extreme temperatures but also from the near-vacuum. The thin atmosphere also provides little protection against impacts.

On Venus, at the altitude of the supposed floating cities, breathable air would be a lifting gas, and thus, storage of breathable air would also double as support for the aerostat habitats. The temperature and pressure at that altitude is very similar to conditions on Earth, and thus humans would only need to be protected from corrosive gases (something we're already very much capable of doing). Leaks in the air torus would diffuse very slowly due to the minute pressure differential, and wouldn't be overly dangerous. The atmosphere of Venus rotates much more quickly than the planet itself, and thus the day/night cycle would be fairly tolerable. We already have materials that can be structurally sound in a corrosive environment ; the engineering challenges are great but not insurmountable, although the same could be said for Mars as well. Essentially, Venus would be a better option for human reasons - no artificial gravity necessary, no chance of getting exposed to a near-vacuum or flash-freeze temperatures. Also, Venus is much more protected from meteorite impacts due to its thick atmosphere. Even at the altitudes the aerostats would be floating at.

[IronBeer]

...Mars has much more extreme temperatures,...

What.

[TwentyPercentCooler]

...Mars has much more extreme temperatures,...

What.

I'm sorry, I should have clarified. The aerostat habitats on Venus will be at an altitude such that the insane pressure-cooker surface temperatures of Venus are reduce to a much more livable range of approximately 30-115 degrees F, in comparison to the average surface temp of -81 F on Mars.