Author Topic: Venus: Formerly 70F to 120F?  (Read 267 times)

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Offline Soldier of FORTRAN

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Venus: Formerly 70F to 120F?
« on: September 23, 2019, 09:45:38 PM »
Article: Could Venus have been habitable?
From: Phys.org
Date: 2019 SEP 22

Quote
Venus may have been a temperate planet hosting liquid water for 2-3 billion years, until a dramatic transformation starting over 700 million years ago resurfaced around 80% of the planet. A study presented today at the EPSC-DPS Joint Meeting 2019 by Michael Way of The Goddard Institute for Space Science gives a new view of Venus's climatic history and may have implications for the habitability of exoplanets in similar orbits.

Forty years ago, NASA's Pioneer Venus mission found tantalising hints that Earth's 'twisted sister' planet may once have had a shallow ocean's worth of water. To see if Venus might ever have had a stable climate capable of supporting liquid water, Dr. Way and his colleague, Anthony Del Genio, have created a series of five simulations assuming different levels of water coverage.

In all five scenarios, they found that Venus was able to maintain stable temperatures between a maximum of about 50 degrees Celsius and a minimum of about 20 degrees Celsius for around three billion years. A temperate climate might even have been maintained on Venus today had there not been a series of events that caused a release, or 'outgassing', of carbon dioxide stored in the rocks of the planet approximately 700-750 million years ago.


...

To simulate the environmental conditions at 4.2 billion years ago, 715 million years ago and today, the researchers adapted a 3-D general circulation model to account for the increase in solar radiation as our Sun has warmed up over its lifetime, as well as for changing atmospheric compositions.

Although many researchers believe that Venus is beyond the inner boundary of our Solar System's habitable zone and is too close to the Sun to support liquid water, the new study suggests that this might not be the case.

...

At 4.2 billion years ago, soon after its formation, Venus would have completed a period of rapid cooling and its atmosphere would have been dominated by carbon-dioxide. If the planet evolved in an Earth-like way over the next 3 billion years, the carbon dioxide would have been drawn down by silicate rocks and locked into the surface. By the second epoch modelled at 715 million years ago, the atmosphere would likely have been dominated by nitrogen with trace amounts of carbon dioxide and methane—similar to the Earth's today—and these conditions could have remained stable up until present times.

The cause of the outgassing that led to the dramatic transformation of Venus is a mystery, although probably linked to the planet's volcanic activity. One possibility is that large amounts of magma bubbled up, releasing carbon dioxide from molten rocks into the atmosphere. The magma solidified before reaching the surface and this created a barrier that meant that the gas could not be reabsorbed. The presence of large amounts of carbon dioxide triggered a runaway greenhouse effect, which has resulted in the scorching 462 degree average temperatures found on Venus today.

...

There are still two major unknowns that need to be addressed before the question of whether Venus might have been habitable can be fully answered. The first relates to how quickly Venus cooled initially and whether it was able to condense liquid water on its surface in the first place. The second unknown is whether the global resurfacing event was a single event or simply the latest in a series of events going back billions of years in Venus's history.

"We need more missions to study Venus and get a more detailed understanding of its history and evolution," said Way. "However, our models show that there is a real possibility that Venus could have been habitable and radically different from the Venus we see today. This opens up all kinds of implications for exoplanets found in what is called the 'Venus Zone', which may in fact host liquid water and temperate climates."

So, if we figure how to sequester carbon at-scale here on Earth, does this mean could immediately get cracking on terraforming Venus?  Because that'd be great.
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Offline 2397

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Re: Venus: Formerly 70F to 120F?
« Reply #1 on: September 24, 2019, 02:46:51 AM »
Venus' atmosphere is about 93 times as massive as Earth's, but it's nearly all CO2, so it has about 225000 times as much CO2 (although the ratio could go down to a half or a quarter of that in the relatively near future).

Could we do it in hundreds of thousands or millions of years, given that we've figured out how to terraform Earth in the centuries that civilization has left at most? Maybe. I'd prefer to crash Mercury into it to give it an iron core, and wait around for it to cool down before starting to work out the details.
« Last Edit: September 24, 2019, 02:48:56 AM by 2397 »

Offline John Albert

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Re: Venus: Formerly 70F to 120F?
« Reply #2 on: September 24, 2019, 05:16:52 AM »
I'd prefer to crash Mercury into it to give it an iron core, and wait around for it to cool down before starting to work out the details.

Assuming the giant-impact hypothesis is correct, it took something like 350-400 million years for Earth to cool down to habitable temperatures after the hypothetical impact of Theia. It took at least 100 million years just for oceans to form.
« Last Edit: September 24, 2019, 05:19:57 AM by John Albert »

Online Noisy Rhysling

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Re: Venus: Formerly 70F to 120F?
« Reply #3 on: September 24, 2019, 06:26:25 AM »
So we should get cracking now then?
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Offline swan

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Re: Venus: Formerly 70F to 120F?
« Reply #4 on: September 24, 2019, 12:01:24 PM »
I'd prefer to crash Mercury into it to give it an iron core, and wait around for it to cool down before starting to work out the details.

That's always been my favorite plan, though I'd actually move Venus out to Mars' orbit and let it all happen there, since by the time we could start working on it our sun will be putting out more heat. Maybe even break up Enceladus and toss the icy chunks into its Roche limit to get a jump start on the cooling and watering process.

Online Awatsjr

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Re: Venus: Formerly 70F to 120F?
« Reply #5 on: September 24, 2019, 12:12:10 PM »
By the time we can do any of that stuff we will have found a different solution.

Offline swan

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Re: Venus: Formerly 70F to 120F?
« Reply #6 on: September 24, 2019, 12:17:06 PM »
By the time we can do any of that stuff we will have found a different solution.

I sure hope so...

Offline random poet

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Re: Venus: Formerly 70F to 120F?
« Reply #7 on: September 24, 2019, 12:20:40 PM »
By the time we can do any of that stuff we will have found a different solution been extinct for centuries.

Fixed that for you.
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Offline John Albert

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Re: Venus: Formerly 70F to 120F?
« Reply #8 on: September 24, 2019, 05:28:21 PM »
By the time we can do any of that stuff we will have found a different solution been extinct for centuries.

Fixed that for you.

I was going to say we'll have been extinct for hundreds of millions of years, but I like your optimism.

Offline daniel1948

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Re: Venus: Formerly 70F to 120F?
« Reply #9 on: September 24, 2019, 06:23:55 PM »
There are people who think that it would be easier and cheaper to colonize Venus than to colonize Mars. At an altitude of 50 km the Venereal atmosphere is 1 ATM (Earth sea-level pressure), but dense enough that an 80% nitrogen, 20% oxygen mix has 80% of the lifting power of helium here on Earth. These people want to build floating cities 50 meters above the surface of Venus. All you have to be concerned about are the sulfuric-acid clouds/rain and the lack of resources.

If it would take us a hundred million years to figure out how to colonize Mars, we could probably colonize Venus in a mere fifty million years. Considering that we cannot even muster the political will to keep Earth habitable, I figure that if we did colonize either planet, we'd probably ruin it before another hundred years were up.
Daniel
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Online Awatsjr

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Re: Venus: Formerly 70F to 120F?
« Reply #10 on: September 24, 2019, 10:37:49 PM »
By the time we can do any of that stuff we will have found a different solution been extinct for centuries.

Fixed that for you.

Lol

 

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