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What is a possible way of making Venus more habitable by getting rid of at least some of the thick atmosphere and thereby lowering the pressure and heat.

At this point all I can think of is some sort of massive explosive event like a big asteroid or a nuclear weapon. But it just doesn't seem enough unless it's big enough to destroy the whole planet.

I'm not thinking in terms of strolling around outside breathing air, but habitable enough to do some industrial mining in suits and domed communities.

There are questions already on terraforming Venus, but I don't see any remotely feasible answers that would make it habitable in the way earth is before our species went extinct. So my question is really about partially terraforming for the sake of exploiting it's minerals and metals.

Assume expense isn't a problem and space travel has become relatively easy throughout the solar system due to a new fuel which is rarish elsewhere but abundant on Venus if we can just get our hands on it.

Perhaps an enormous asteroid didn't impact but instead just missed actually passing through the atmosphere? I'm happy with a lucky natural event that allows humans to exploit Venus. Bonus if it speed up the rotation. Whatever fluke would be needed is fine, because the 'real life' earth is an incredible fluke.

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closed as unclear what you're asking by L.Dutch, JDługosz Mar 17 '17 at 4:23

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    $\begingroup$ I believe a large part of the problem are the high temperatures that Venus experiences. You could drop vast amounts of dirt/ash in the atmosphere (could be something more advanced like nanobots) and form thick clouds which reflect the Sun's heat back out into space. Then, as the planet cools, tap "holes" into the upper atmosphere (with nukes, maybe?), allowing some atmosphere to escape. This process would take decades, or more likely centuries, however. Storing gases in polar ice caps would probably be easier than nuking it, but again, takes longer. $\endgroup$ – AndreiROM Mar 16 '17 at 13:11
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    $\begingroup$ Are you looking for something different than what is written, for example, here en.wikipedia.org/wiki/Terraforming_of_Venus ? $\endgroup$ – L.Dutch Mar 16 '17 at 13:13
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    $\begingroup$ Terraforming a planet is pretty clearly on-topic. $\endgroup$ – James Mar 16 '17 at 13:47
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    $\begingroup$ Does any of worldbuilding.stackexchange.com/questions/25802/… or worldbuilding.stackexchange.com/questions/14050/… or worldbuilding.stackexchange.com/questions/58571/… … in any case, many of the answers address this Q. All: know what's already been posted before saying the same thing again! $\endgroup$ – JDługosz Mar 17 '17 at 3:52
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    $\begingroup$ Asking a question again because the old answers aren’t good enough is not a reason for having a duplicate: set a bounty on the old question or post comments on answers you would criticise. If the same answers fit your question then it's a dup even if you claim otherwise. You need to clarify how your question is different, really, not just that you want to go again. $\endgroup$ – JDługosz Mar 17 '17 at 4:27
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Most of these answers are relatively "small potatoes" in terms of terraforming. Playing around with asteroids, sunshades, nuclear explosions etc. can certainly do the job, but take decades to centuries of work, and when you get down to it, Venus will still be blisteringly hot du to insolation, have very little water and a long, retrograde day (the sun rises in the West and Venus rotates once every 243 Earth days. Daylight savings time is not likely to be an issue on Terraformed Venus!

A researcher named Paul Birch developed an amazing scheme which solves a number of these problems at once. Using a stream of high speed particles launched from an accelerator ring orbiting the sun to transfer momentum to the target planet (Venus is only one instance where it could work), the planet could have its rotation and orbital parameters adjusted to your liking.

The paper "Terraforming Venus Quickly" outlines this plan in greater detail. Using devices called "light sail windmills" to provide the energy to accelerate the pellet stream, and a giant sunshade to cool the planet, an ice moon from the Jovian system could be moved out from Jupiter and crashed into Venus to supply an ocean's worth of water. Applying the pellet stream energy directly can set up a more suitable rotational period for Venus (How to spin a planet), and the planet can be moved to a larger orbit where there is less insolation (How to move a planet).

To give you an idea of the scale of this plan, moving Venus could take ~30 years and require harnessing .2% of the Solar luminosity during that period. While moving and spinning a planet in 30 years certainly makes the project achievable in the lifetime of an engineer working on the project, I suspect the planet will be quite unstable and wracked by earthquakes for decades if not centuries due to the stresses induced upon it.

Since Terraforming is, by definition, making a planet more Earthlike, then applying fabulous amounts of energy and moving the planet into an Earthlike orbit and spinning it up to an Earthlike rotation should be non negotiable.

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  • $\begingroup$ Good answer, yes, I'm looking for the quick fix a few decades at most rather than millenia, so a big event rather than subtle ones. But I'm not interested in making it that earthlike, the question is 'Start to terraform' I do like the idea of crashing an ice moon. $\endgroup$ – Kilisi Mar 17 '17 at 3:51
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The two main problems with Venus is the heat and the high content of carbon dioxide in the atmosphere.

In the future there may be a way of devolving carbon dioxide into its constituent Carbon and Oxygen, which are a lot more friendly. Right now, it's a difficult process (as illustrated by our esteemed Chemistry Stack.

Yutaka Tamaura and Masahiro Tahata, Complete reduction of carbon dioxide to carbon using cation-excess magnetite, Nature, 1990, 346, 255-256, [[DOI][1]]

they heated magnetite ($\text{Fe}_3\text{O}_4$) at 290 °C for 4 hrs in a stream of hydrogen to yield a material which turned out to be stable at room temperature under nitrogen. This material, $\text{Fe}_{3+\delta}\text{O}_4 (\delta=0.127)$, i.e. the metastable cation-excess magnetite is able to incorporate oxygen in the form of $\text{O}^{2-}$.

Under a $\text{CO}_2$ atmosphere, the oxygen-deficient material converted to "ordinary" $\text{Fe}_3\text{O}_4$ with carbon deposited on the surface.

However, the heat of Venus might help overcome that difficulty (the surface of Venus has a mean temperature of 460 °C)

Lowering the concentration of $\text{CO}_2$ should in theory negate the runaway greenhouse effect and remove some heat making the environment a bit more friendly to work in.

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  • $\begingroup$ I edited the question to include the possibility of an asteroid near miss $\endgroup$ – Kilisi Mar 16 '17 at 20:23
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One scenario I have heard is to seed the upper atmosphere with photosynthetic and chemosynthetic bacteria or archae that would break down the carbon dioxide and sulfur in the atmosphere, respectively. The large amount of sunlight would have the photosynthetic bacteria grow and the thick atmosphere would help both organisms stay airborne.

Perhaps you could start with bacteria or archae that are highly resistant to acidity, temperature, and radiation. Then you could splice in genes for photosynthesis into one group and sulfur-eating into another. You wouldn't want to splice both into the same cells because then the cells would use whatever is most readily available rather than consuming both at the same time.

This would result in lower temperatures (due to a reduced greenhouse effect), less toxic atmosphere, breathable oxygen, and clearer skies. However, it may take too long for your scenario.

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    $\begingroup$ The only problem is that the reduction of SO$_2$ into sulfur and oxygen requires energy (the process being endothermic) instead of producing it. Implying that while sulfur synthesizing bacteria do exist, the prospect of particularly reducing SO$_2$ into its constituents is not a very bright one. $\endgroup$ – Youstay Igo Mar 16 '17 at 19:05

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