[Space] What is the 'Gaia' type of garden worlds like? ('Habitability 9').

[Phantasm]

Originally Posted by Warlockco

To me a "Gaia" type world is going to be an idealized version of Earth as far as what a human would think.

So first off gravity is going to be 1 gravity.
The world with most likely be 2/3 to 3/4 water, mostly in oceans.
All Terran crops and animals can live and thrive on the world without any adaptation.
All native crops and animals can be consumed without any adaptation.
Axial tilt of the world will be roughly 23.5 degrees, so seasons and weather patterns should be close to Earth normal.

Add into this a lack of arid, sandy, and extremely rocky mountainous regions, permitting greater arable land for farming and herding.

[tshiggins]

Originally Posted by sir_pudding

• Large temperate zone and minimal seasons. Probably by a combination of favorable orbit, low axial tilt and greenhouse conditions.
• Low salinity in the seas; all bodies are freshwater.
• Relatively larger surface area of landmasses.
• Primitive or no development of native pathogens.
• High degree of nitrogenation of the soil.

I'd go with most of this. The low axial tilt seems obvious, as does high nitrogen content of the soil. There's a lot to be said for properly twisted amino acids, because that means humans can eat the native plants and animals, even though it means the native animals and pathogens can also eat us.

I don't think low-salinity oceans is a viable expectation, but a better distribution of ocean and land would be nice. A dozen or so land-masses the size of Australia, distributed more or less evenly around the planet, might work out well, especially if they were connected with archipelagos. That means a lot of shallow waters teeming with life, and the lack of really huge expanses of open ocean minimizes the intensity of coriolis storms.

I hadn't thought of the vulcanism thing, but that makes sense, too. Also, I'd say no huge extremes in altitudes. No mountains larger than about the Appalachians or the Pyrenees, which result in minimal rain-shadows or other atmospheric weirdness.

Lots of flora and fauna, everywhere.

[sir_pudding]

Originally Posted by tshiggins

I don't think low-salinity oceans is a viable expectation

It's the expectation if you terraform an arid world, until the new seas have had time to dissolve salts anyway, which takes megayears.

I could also imagine biogenic processes that clean oceanwater on a natural gaia.

[whswhs]

Originally Posted by sir_pudding

Indeed, the very premise here is that there exists possible planets that are more habitable than homeworlds!
Sure, but ericthered specified "As long as we can still breathe the air and go shirtsleeve and don't get knocked over by super hurricanes."

To which you responded that people like vegetation and warm weather. Which in context seems almost euphemistic, like a colony program trying to sell a hothouse as a paradise.

No, actually, I was responding to "That doesn't sound like Gaia for humans, it sounds like Gaia for crops." That's why my primary point was that in my experience, humans enjoy places with vegetation. I was saying that Gaia for crops very like WAS Gaia for humans.

[Warlockco]

Originally Posted by sir_pudding

That's Earth, which is by definition not a Gaia world.

I did say IDEALIZED.

[Fred Brackin]

Originally Posted by sir_pudding

• Large temperate zone and minimal seasons. Probably by a combination of favorable orbit, low axial tilt and greenhouse conditions.

To try and dress this up with semi-plausible geophysick-y technobabble let's say that we have a world where Earth-like continent forming didn't happen and the preferred method of landmass creation is magma plumes forming large volcanic islands over time. Further, the magma plumes cluster in the equatorial regions putting a planet-surrounding belt of these island in the tropics.

So basically we're mass-producing Hawaii. I won't swear it's an optimum human habitat but it'd be a great place to sell real estate. That might be because the human types would be voting with their feet and money to move there telling you that they thought it was pretty close to an optimum habitat.

Note that the "big island" actually is quite big and gives you not only warm coastal regions but fertile and comfortable uplands as well.

You could also build high altitude observatories and/or spaceports on the peaks of the mountains that had gone cold.

[whswhs]

Originally Posted by Fred Brackin

So basically we're mass-producing Hawaii. I won't swear it's an optimum human habitat but it'd be a great place to sell real estate. That might be because the human types would be voting with their feet and money to move there telling you that they thought it was pretty close to an optimum habitat.

Note that the "big island" actually is quite big and gives you not only warm coastal regions but fertile and comfortable uplands as well.

You could also build high altitude observatories and/or spaceports on the peaks of the mountains that had gone cold.

I don't know if I'd like to live in Hawaii; I'm actually liking Riverside's climate now that we've moved there, and I think Hawaii's a lot wetter, isn't it? But it's an elegant handwavy concept for a planet.

[Fred Brackin]

Originally Posted by whswhs

I don't know if I'd like to live in Hawaii; I'm actually liking Riverside's climate now that we've moved there, and I think Hawaii's a lot wetter, isn't it? But it's an elegant handwavy concept for a planet.

A drier part of the island is where those uplands come in. You get grasslands instead of rain forests but it's still in the 70s every day.

[sir_pudding]

I was thinking of kind of a super-goldilocks situation, where the the planet is exactly the right size and density, in exactly the right orbit, with exactly the right atmosphere to just have perfect greenhouse conditions without a runaway so that warm temperatures are fairly evenly distributed around the planet.

[David Johnston2]

Let's consider Planet Optimum, the best planet you can randomly roll.

Dense Breathable Atmosphere, hydrographic percentage of between 80 and 90%, default climate type warm, medium vulcanism. light tectonic activity, RVM +2, Habitability +6, .75 density. 1.0 gravities. Black Body temperature 312, Diameter 1.33 resulting in an optimum TL 10 carrying capacity of 6.637 billion human beings. This is nearly the maximum carrying capacity possible. Most of the garden planets you actually roll will be able to comfortably support less than half that many humans. As you know Bob, by GURPS rules, Earth is well above its carrying capacity leading to most of the planet living at much less than a TL 8 average income.

You actually want a higher hydrosphere than that of Earth because oceans are a much richer resource than deserts for food production. Relatively small continents will be wetter and more fertile. Low density increases diameter, and diameter increases carrying capacity. As for increasing habitability above the random maximum, that would pretty much require native plant life that somehow manages to be more efficient in converting sunlight into calories, as well as native life that is really good at identifying and fertilizing tapped out soil.