[Space] Terraformed Venus as a setting

[acrosome]

I've mentioned elsewhere that I want to set an ultra-low-fantasy (no magic) campaign on a terraformed Venus, a few millennia after some sort of cataclysm. Venus works far better than Mars for keeping the backstory a secret from the players- the gravity is close enough to Earth's that the difference can be safely disregarded, it's closer to the same size, and not every scifi fanboy in existence would instantly recognize a map of the planet as they would for Mars, etc.

But the problems are manifold.

First, to get this out of the way, yes I have to hand-wave an awful lot of the terraforming, though having TL12 planetary engineers for playthings helps a lot. That's not what I'm going to get into here. A lot of the terraforming stuff I found online are certainly interesting, but don't work for my purposes. I need something that is stable on its own.

So I'm trying to make decisions about some very basic stuff, and I'd appreciate your thoughts.

First, Venus's year is 224.7 [24-hour] days. That's workable, but if I wanted to is there a larger orbit to which I could move Venus safely- i.e. without doing horrible things to the Earth? How far out could I move it without adversely impacting Earth's orbit, and how long would the year be? Could I move it into Earth's L4 or L5? I found a lot of stuff online about Lagrangian planets but everything seems to assume that one is much larger than the other, which would not be the case here, so I have no idea what the repercussions would be. Would both planets orbit their respective Lagrange points, like Trojan asteroids? None of the other Langrangian points work- L3 was very tempting, but it is unstable on the order of 150 years. Or am I missing something elementary?

A world without a moon would actually make for a pretty interesting setting, but it has problems- no tides, impact upon some forms of wildlife, etc. Plus, everyone likes moons and adding a moon to Venus would, again, help disguise the planet's identity from the scifi fanboys. So I'm thinking about finding an appropriately-sized body (or two) in the solar system and moving it to be Venus's new moon. Anyone have good ideas for candidates? I'd want it big enough to cause appreciable tides, though they needn't be quite as large as Earth's. I just need enough to flush out the estuaries and keep the mangroves alive. What other effects would this have? The rest of the planet would tide as well, obviously, so- might it restart vulcanism? Like moons, everyone likes volcanoes...

Venus's current solar day is 116.75 [24-hour Earth] days long. Unworkable. I found various terraformation schemes online that could explain spinning it up as fast as a 14-day solar day. That actually intrigued me- having the "fortnight" as the basic timekeeping unit- but I've decided that it probably causes a lot of problems, and would likely raise the suspicions of scifi-fanboy players. Having the sun rise in the West is odd enough to keep things interesting for my purposes. Also, I have no idea how many Hadley cells a 14-day rotation would cause, whereas I'm pretty confident that I'd get Earth-like cells at a similar rotation. No one is quit sure what Venus's interior is like beyond that it's pretty clear that it doesn't have plate tectonics, so spinning up might plausibly lead to mantle cells and a magnetic field- another bonus.

(I'm going to fix that axial tilt, too. A world without seasons strikes me as bland.)

Input?

[Phantasm]

Originally Posted by acrosome

I've mentioned elsewhere that I want to set an ultra-low-fantasy (no magic) campaign on a terraformed Venus, a few millennia after some sort of cataclysm. Venus works far better than Mars for keeping the backstory a secret from the players- the gravity is close enough to Earth's that the difference can be safely disregarded, it's closer to the same size, and not every scifi fanboy in existence would instantly recognize a map of the planet as they would for Mars, etc.

But the problems are manifold.

First, to get this out of the way, yes I have to hand-wave an awful lot of the terraforming. That's not what I'm going to get into here. A lot of the terraforming stuff I found online are certainly interesting, but don't work for my purposes. I need something that is stable on its own.

So I'm trying to make decisions about some very basic stuff, and I'd appreciate your thoughts.

First, Venus's year is 224.7 [24-hour] days. That's workable, but if I wanted to is there a larger orbit to which I could move Venus safely- i.e. without doing horrible things to the Earth? How far out could I move it without adversely impacting Earth's orbit, and how long would the year be? Could I move it into Earth's L4 or L5? I found a lot of stuff online about Lagrangian planets but everything seems to assume that one is much larger than the other, which would not be the case here, so I have no idea what the repercussions would be. Would both planets orbit their respective Lagrange points, like Trojan asteroids? None of the other Langrangian points work- L3 was very tempting, but it is unstable on the order of 150 years.

A world without a moon would actually make for a pretty interesting setting, but it has problems- no tides, impact upon some forms of wildlife, etc. Plus, everyone likes moons and adding a moon to Venus would, again, help disguise the planet's identity from the scifi fanboys. So I'm thinking about finding an appropriately-sized body (or two) in the solar system and moving it to be Venus's new moon. Anyone have good ideas for candidates? I'd want it big enough to cause appreciable tides, though they needn't be quite as large as Earth's. What other effects would this have? The rest of the planet would tide as well, obviously, so- might it restart vulcanism? Like moons, everyone likes volcanoes...

Venus's current solar day is 116.75 [24-hour Earth] days long. Unworkable. I found various terraformation schemes online that could explain spinning it up as fast as a 14-day solar day. That actually intrigued me- having the "fortnight" as the basic timekeeping unit- but I've decided that it probably causes a lot of problems, and would likely raise the suspicions of scifi-fanboy players. Having the sun rise in the West is odd enough to keep things interesting for my purposes. Also, I have no idea how many Hadley cells a 14-day rotation would cause, whereas I'm pretty confident that I'd get Earth-like cells at a similar rotation. No one is quit sure what Venus's interior is like beyond that it's pretty clear that it doesn't have plate tectonics, so spinning up might plausibly lead to mantle cells and a magnetic field- another bonus.

Input?

I like this. A few things:

What TL would the terraforming have taken place at? TL10+ is needed for the kinds of terraforming you're looking for, maybe even TL 12 for doing it super-fast.

Ceres may be the best choice to make into a moon. It's large enough that it can have a significant impact on tides as well as close enough that it can be pulled into orbit around Venus without too much trouble - as opposed to the larger dwarf planets out past Neptune.

For the Lagrange points, the L4 and L5 points are 60 degrees ahead and behind the planet in its orbit, and are "stable" in that things are drawn towards them rather than away from them (like in the L1, L2, and L3 points). However, the maximum theoretical mass of an object in a Lagrange point without destabilizing it is much smaller. The current "Big Splat" theory is that a Mars-sized planet formed in one of Earth's Lagrange points and ultimately ended up colliding with Earth to form the moon, so moving an object of roughly the same mass into a Lagrange point is going to destabilize the orbit of both bodies.

I don't think you can "move" Venus that far out. I did the math one time (headache that it was) several years back, doing research for a system generator, and it showed that Venus's orbit is roughly the perfect equilibrium between Mercury's and Earth's. In short, if you want to keep things "realistic"

As for the day, I wouldn't actually "explain" anything. Make the day somewhere between 18 and 30 hours, and in the "Big Reveal" just say "Earth hit TL12 and terraformed Venus".

[Nereidalbel]

If you want a decent moon for Venus, pull the proto-planet Ceres into orbit. It's already large enough to be round, and it appears to have a decent amount of water on it. A habitable moon is always interesting, especially when your people on the ground can look up to see life, but just can't get to it...

As for the length of a day on Venus, how much you can speed it up is all about how much effort your TL12 guys want to put into it.

[DangerousThing]

I'm curious, why Venus?

I'm thinking that were I to do something like this, I'd have Earth terraformed after a really serious ecological collapse, which would also explain why mankind went to the stars.

Then some TL 12 guys came back and for nostalgia's sake fixed Earth up. Though I'd probably have them get bored half way through and leave some rough edges.

Some really poor research on the terraformer's parts could have all sorts of interesting places. Dinosaurs could coexist with mammals. If they watched the wrong movies, perhaps Monster Island and Godzilla now exist?

If you really want Venus, at TL 12, if they can significantly change a planet's orbit they can change the length of the day easily.

[Nereidalbel]

Originally Posted by DangerousThing

Stuff

Because it's DIFFERENT. Also, you know, no ancient ruins hinting at the truth and such.

[Fred Brackin]

Originally Posted by acrosome

Input?

Moving Venus out to Earth's orbit makes for a "natural" solution to a serious problem. Where it is now Venus gets too much sunlight to maintain Earth-like conditions even with the right atmosphere.

The various solutions considered during the Transhuman Space playtest involved a single _big_ sunshade or a _lot_ of smaller ones. Even with a 14 day rotation the naked eye astronomy issues would be complicated and fairly obvious.

So use (Big!)reactionless thrusters to move Venus o0ut to the Counter-Earth position and give it a day-length that's somewhere in Earth's ballpark. You can flip the planet over to conventional rotation in the process too.

Venus probably does have a molten iron core and spinning it up to Earth-like speeds might cause it to generate a magnetic field.

A moon is good. It prevents the day from slowing rapidly again and keeps the planet from flipping over (again). The lack of a moon to stabilize things is probably one of the main reasons Venus flipped over in the first place.

Ceres is a simple solution and probably good enough. Stealing one of Jupiter's bigger moons requires careful choice as many of them are mostly ice and would melt at 1 AU. Titan would be interesting but might start losing atmosphere.

The moons of Uranus are no better than Ceres and if you snitch the big moon from Neptune (Nereid?) you might see issues from transitioning from an orbit where nitrogen is a solid as hard as granite.

Of course, you may have to grab Nereid to provide the nitrogen for Venus' new atmosphere anyway. Then you could make whatever sort of moon you want out of the leftovers. Nitrogen is the best candidate to dilute the oxygen in Venus' new atmosphere but nitrogen is not common in the inner system.

[PTTG]

If you can change the orbit of a terrestrial planet, then you can spin it up too. Putting a dwarf planet in orbit is an afterthought at that point. It would almost definitely involve gravity or inertia manipulation, because there's no way that any reaction-based propulsion system could one, move a dwarf planet, let alone a terrestrial one, or two, spin a planet up without destroying it.

Even after doing this, Venus' map would be radically altered, because the centripetal force would decrease the effective gravity near the equator. It might be a small change, but it would mean that trillion of tons of terrain is suddenly a few million tons lighter. Earthquakes, volcanoes, etc.

If you want to show just how powerful these people were, go ahead and put it in a mutual orbit with earth. Luna could orbit the center of mass. If earth is really close, you could have it tidally locked with Venus, meaning that from half the world you would see the huge blue-white orb of where the myths say all people came from..

[acrosome]

Originally Posted by tbrock1031

Ceres

Originally Posted by Fred Brackin

Ceres

Y'know, I thought of Ceres but I was thinking that it would be too small to generate significant tides. Am I wrong?

Originally Posted by tbrock1031

However, the maximum theoretical mass of an object in a Lagrange point without destabilizing it is much smaller.

That's what I thought. I suppose that L3 is thus also a no-go? Because Fred likes it:

Originally Posted by Fred Brackin

So use (Big!)reactionless thrusters to move Venus o0ut to the Counter-Earth position and give it a day-length that's somewhere in Earth's ballpark. You can flip the planet over to conventional rotation in the process too.

Regarding:

Originally Posted by DangerousThing

I'm curious, why Venus?

I thought I had covered that but maybe not, so to rephrase, I guess that I can't decide if I'm a fantasy-fanboy or a scifi-fanboy. I have commitment issues. Maybe I feel that it allows me (as GM) just a hair more suspension of disbelief than a scenario where a whole 'nuther world populated by humans exists in a different dimension along with gods, magic, elves, etc. Or whatever. My reasons for Venus over Mars I think I covered adequately, above. Similar problems with Earth- it's hard to fudge major coastlines that much unless we're talking million-year timescales, and that would give it away. And it's nice to have a new playground- y'know? Consider Artemis Chasma. Wow.

And- why the hell not? :)

Originally Posted by tbrock1031

As for the day, I wouldn't actually "explain" anything. Make the day somewhere between 18 and 30 hours, and in the "Big Reveal" just say "Earth hit TL12 and terraformed Venus".

Originally Posted by Nereidalbel

As for the length of a day on Venus, how much you can speed it up is all about how much effort your TL12 guys want to put into it.

Originally Posted by DangerousThing

If you really want Venus, at TL 12, if they can significantly change a planet's orbit they can change the length of the day easily.

Yeah, I'm already 99% certain I'll make the day something closer to 24 hours. I'll add more axial tilt, too, to get seasons. It's looking like moving the orbit isn't going to fly, though, so I guess I have to have a permanent soletta or something similar. I guess a TL12 soletta might effectively be a permanent structure, so long as it wasn't attacked during the cataclysm.

Originally Posted by Fred Brackin

The various solutions considered during the Transhuman Space playtest involved a single _big_ sunshade or a _lot_ of smaller ones. Even with a 14 day rotation the naked eye astronomy issues would be complicated and fairly obvious.

Yeah. I played with the idea of a ring of micro-reflectors in orbit, but you really can't do that in a way that shields the poles as well as the equator (or whatever line the ring orbits). You could make a huge constellation of mirror particles in many different orbits but that will not look natural, whereas the players might just chalk a ringed world up to GM hubris. Yet with a ring I'd have a livable equator and scorching hot poles, and that's weird enough to give the players too many clues, too. Grr.

Originally Posted by Nereidalbel

Because it's DIFFERENT. Also, you know, no ancient ruins hinting at the truth and such.

This.

But there are ancient ruins- I'm just going to present them in unrecognizable ways. I'm toying with the idea of a few hundred miles of fallen elevator cable. There will be lots of underground facilities, though after a couple of millennia not much is left but strangely-precisely cut rock.

See my critter, too.

And here's an initial impression of what the planet will look like.

I've come up with several great campaign ideas, actually. One would be like David Drake's The General series- a surviving AI picks the PCs as his agent. That's for later on, though, as the Big Reveal when the campaign gets stale and the GM is running out of original ideas.

There are a few surviving "immortals" still around- all barking mad in one way or another from the cyberwar component of the cataclysm, a few of whom I'm provisionally naming after historical immortals. Koschi is a psychopath who is immortal via brain taping and kidnapped bodies, and who starts death cults as a hobby. Cartaphilas is actively trying to retard technologic progress 'until the human race is morally advanced enough to handle it.' The Immortal Emperor has a megalomaniacal plan to recreate an ideal China, and is well on his way. The Orbital AI was just mentioned above- he is a natural enemy of Cartaphilas since he wants to progress technology far enough to free him from his prison in the egg-sized weather satellite to which he fled at the cataclysm. Another recently-awakened immortal killed and replaced a princess in some or other kingdom 25 years ago and set about empire-building. She's now Jean d'Arc meets Queen Elizabeth, but people are starting to wonder why she doesn't seem to age, and wisper about witchcraft. Etc.

One of my design goals is also to marginalize Abrahamic religions, to try to keep things unfamiliar to players. I propose a Nostalgic Era just before the collapse, when people were experimenting with obscure historical religions as well as their own odd New Age stuff, and the religions on my world will be descended from these. One culture will be based on the Modern-Indo-European movement, for instance, including language and religion. My Islam-equivalent will be based upon Baha'i. But since Islam considers Baha'i to be apostasy, there was a conflict, which Baha'i won (mostly due to the influence of a now-decease immortal prophet), though it lost much of it's peacenik character in the process. There will be a very weird new-agey Gnostic-like church in one region, with Ascended Masters and the Seven Rays, and who believe that any other religion based upon creator-god is the equivalent of satanism. (They mostly wiped out the Jews and Christians.) And it will have a schism... Etc. Etc. You can still find remote and isolated villages of Abrahamic religions if you look hard enough, though.

Originally Posted by PTTG

If you want to show just how powerful these people were, go ahead and put it in a mutual orbit with earth. Luna could orbit the center of mass. If earth is really close, you could have it tidally locked with Venus, meaning that from half the world you would see the huge blue-white orb of where the myths say all people came from..

Way cool, indeed, but not what I'm going for. I'd like to try to keep the deep backstory secret. This is why L3 would be so great, if it would work. The Baha'i, for instance, would pray toward the sun because the temple in Haifa is on the other side, though they would have forgotten that reason.

[Nereidalbel]

Originally Posted by acrosome

Y'know, I thought of Ceres but I was thinking that it would be too small to generate significant tides. Am I wrong?

It's large enough for gravity to crush rock into a round shape. It may need to orbit a bit closer than Luna, but it will do.

[Proteus]

Originally Posted by acrosome

A world without a moon would actually make for a pretty interesting setting, but it has problems- no tides, impact upon some forms of wildlife, etc.

You don't need a moon to have tides; Earth has both lunar and solar tides.

In fact, I think Venus' solar tides ought to be about three times the size of Earth's (1.0 AU / 0.7 AU cubed) — and, since Earth's solar tidal force is 46% as large as the lunar (see http://en.wikipedia.org/wiki/Tide#Forces ), that means you'd actually have tides roughly equivalent to Earth's even without a moon.