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WI: Habitable Venus

SinghSong

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A little something inspired by my musings over on the natural nuclear reactor thread- A fun little-known fact is that radioactive fissile isotopes appear to be significantly more abundant on Venus than they are on Earth; and that this is now believed to be partially responsible for turning Venus into the planet it is today. Recent scientific modelling by NASA, of alternate Earths from formation "dialling the amount of internal radiogenic heat production up and down to see what happens”, showed that when the radiogenic heating was significantly greater than on Earth (as appears to have been the case on Venus), then the planet can’t permanently sustain a dynamo, as Earth did. This is because most of the thorium and uranium end up in the mantle and too much heat in the mantle then acts as an insulator, preventing the molten core from losing heat fast enough to generate the convective motions that produce the magnetic field, and shutting down any possible plate tectonics. With more radiogenic internal heating (from higher concentrations of radioactive isotopes), the planet also has much more catastrophic and violent volcanic activity, venting its internal heat in periodic major resurfacing events.

We now know that Venus is uninhabitable IOTL, at least partially, because it had too much radioactive material at its formation- with this, rather than its slow rotation (with simulations now having shown Venus' core is electrically conductive, and that its rotation speed should indeed be adequate to drive an internal dynamo), having been the primary factor which rendered it incapable of producing a sustained dynamo, to drive a protective magnetic field, being directly responsible for the lack of convection in Venus's core. It's this excess of internal radiogenic heat production, derived from the overabundance of radioactive fissile isotopes on Venus relative to that on Earth, which shut down Venus' plate tectonics and led to a reduced heat flux out of the core through the crust, shutting off its internal dynamo in the process (with this now believed to have happened roughly 1.5-2.5 billion years ago, having been retained for the first 2-3 billion years of Venus' life), and killing off the magnetic field which Venus is now believed to have possessed prior to this, with the overwhelming majority of Venus' water reserves lost to the solar wind in the next billion years following on from this.

So then, in an alternate TL, what if Venus didn't have such an overabundance of fissile material (let's say that ITTL, their abundance on Venus was merely 24% greater than their abundance on Earth, to compensate for its lower mass and pressures being 24% lower in its deep interior than Earth's); and that as a result, the convection in its core did remain capable of sustaining a dynamo, allowing Venus to both sustain active plate tectonics and continue generating its own intrinsic magnetosphere, protecting its water reserves from erosion by the solar wind, all the way to the present day (rather than merely having had surface water and 'a habitable condition' for around 3 billion years, and only managing to sustain this condition until 700 to 750 million years ago, when the near-global resurfacing event triggered the mass release of carbon dioxide from rock on the planet and irreversibly transformed its climate, as concluded by recent studies from September 2019)? Even if life on Venus either didn't exist in this scenario, or remained exclusively microbial, how much more attractive would Venus be than Mars or any other world for human colonization? And what would you expect the 'Race for Venus' to look like?
 
Obligatory:

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But if Venus does seem inhabitable - and IIRC it's easier to reach than Mars - then I'd see both NASA and the Soviet space people, and then the ESA, JAXA et al the space agencies with any level of money, making it clear this is the next goal after the moon and getting support. A lot of ambitious space plans can be written off as pie-in-the-sky by a budget-conscious government but here, we're saying the planet can be feasibly lived on. There's a long-term point to going there and everyone can grasp it
 
A habitable Venus, ignoring for the moment the effects this would have on the history of Earth, would become a key destination for the Earth's space agencies as soon as we were able to confirm its habitability. Mars would still be of interest, but a Venus that is pretty close to being Earth's twin would be a much more interesting target than anything we have had OTL.

(Would we be able to dispatch crewed missions? It is not clear to me we would have the technology to do that safely now. Maybe in this ATL?)
 
(Would we be able to dispatch crewed missions? It is not clear to me we would have the technology to do that safely now. Maybe in this ATL?)

You can theoretically launch a crewed interplanetary mission with 1960s technology. It's just going to be risky and costly, and ever more so as you get backwards in time.
 
I'm actually thinking reverse culture shock from humans who've lived on the Habitable Venus appearing on Earth, and seeing the sky get dark and light and dark and light and dark and light so quickly compared to their home planet's famously slow rotation.
 
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