Life on a Terraformed Venus with extremely slow rotation

I'm going to be gamemaster for an RPG that takes place on a terraformed version of Venus. One interesting fact about the planet Venus is that it has an extremely slow rotation, about 243 days. This means that the days and nights last for approximately 122 days.

1) Could life exist on a planet with such a rotation? 2) If so, what would be the hurdles for living there? How would that life look like and live in order to adapt?

Edited by Fulevert on Feb 27th 2020 at 5:26:23 AM

One question, would the core have been ignited? As it won't support much of anything without a magnetosphere.

Venus has an incredibly thick atmosphere due to a runaway greenhouse effect millions or billions of years in the past. If you could somehow reverse that and bring the atmosphere back to Earth-equivalent pressure, you would immediately run into the problem that the planet has a very weak magnetic field (due to its slow rotation). Charged particles from the solar wind would be able to start stripping the atmosphere away, and there would be significantly increased radiation hazard at ground level. Further, constant ionization of the atmosphere would wreak havoc on communications and electronics. The slightest solar storm could have effects equivalent to the Carrington event on Earth.

"Could life exist on Venus?" is a vague question. Could life exist on its surface now? Almost certainly not. Could life evolve independently after we terraformed it? Not on human time scales; you're talking millions or hundreds of millions of years, and see that bit about the atmosphere getting stripped away. Could Earth life survive on its surface post-terraforming? Well, that is sort of the definition of terraforming: making it suitable for Earth life. With appropriate precautions, absolutely. It is unlikely that we'd reach a point where children can skip across grassy fields in shorts and t-shirts, though.

I should point out that if you're talking about increasing Venus' rotation or reheating its core, that's super-engineering on a scale that is only reasonable for Space Opera of the "don't give a fuck" variety. If we can do that, we're basically gods.

A more plausible near-term concept for colonizing Venus would involve literal floating cities: using balloons to remain aloft in the region of the planet's atmosphere that is close to Earth pressure. You wouldn't be able to walk around outside unprotected thanks to the acid in the air (never mind the solar radiation), and you wouldn't be able to breathe without equipment anyway, but there isn't much new science we'd need to invent to make it possible. Oh, and it'd be easier to get to and from than Mars.

Edited by Fighteer on Feb 27th 2020 at 10:08:34 AM

Thank you for the answer. I suppose I should have been more detailed in my original post. This is an alternative universe where Venus is supposed to be habitable since before humans even existed and there is a race in the 80's and 90's to colonize it between the USA and Soviet Union (heavily inspired by "The Sky People", by S.M. Stirling). I had figured that if the atmosphere is more earthlike in its composition then all I had to worry about was to figure out how life would be able to thrive when daytime and nighttime are so abnormally long. Turns out, after reading your excellent response, that the rotation is slow due to lack of a solid core such as what earth has (I understood you correctly?) and that lack of solid iron core also means a lack of a protective magnetic field which means life would not thrive there at any rate.

SUMMARY: So basically, to have a habitable fictional Venus the planet simply must have a rotation such as earth's, because the implications of it having such a slow rotation means radiation would kill everything on the surface. This is correct?

Edited by Fulevert on Feb 28th 2020 at 3:49:27 AM

You are mixing concepts a little, but there are two basic considerations. Stipulating that Venus has its current rotational period and does not have a runaway greenhouse effect making its atmosphere like swimming in a volcano...

• It is likely that the solar wind would strip away the majority of its atmosphere due to the lack of a protective magnetic field.
• Having little atmosphere, its surface would be bombarded by radiation. Also, liquid water could not exist on the surface.

Either of those would make complex life all but impossible.

Venus also rotates backwards, and one theory regarding that is that Venus had an encounter with a planetary object early in the history of the solar system, which spun it the wrong way. Change that, give Venus a normal rotation, and I think it could easily become a very "Earthlike" planet (with quotes, because conditions would likely be very different there, but at least some form of life would be more likely).

How does a planet rotate backwards, wouldn't its gravity be the same either way?

Edited by Kaiseror on Mar 4th 2020 at 2:57:33 PM

When a cloud of interstellar gas and dust coalesces into stars and planets, any inherent angular momentum it originally carried is preserved and magnified, like the basic metaphor of a dancer bringing their arms close to their body to spin faster.

Any body that forms is likely to inherent the angular momentum of the whole and rotate in the same direction. To disrupt that, you generally need a large gravitational tug or a massive collision.