[Space] World Design errors?

[Vaevictis Asmadi]

Hi folks,

I've been playing with the World Design Sequence. I want to be able to design a species first, then design a world around it, then design the solar system around that. I've also wanted to make possible a wider range of primary stars.

And just double-checking the numbers, I'm getting results that make no sense. Such as RAW garden worlds with so little atmospheric pressure, the water cannot condense.

I've read that there are "unresolved errata" for World Design. Can some kind soul please point me to the thread(s)/post(s) which list those errors and the correct formulas to use instead?

Also, am I correct in calculating "minimum molecular weight retained" (p. 86), that most of the variables cancel out and it's just W = 1/(60 * [size constraint]^2) ?

[David Johnston2]

Originally Posted by Vaevictis Asmadi

Hi folks,

I've been playing with the World Design Sequence. I want to be able to design a species first, then design a world around it, then design the solar system around that. I've also wanted to make possible a wider range of primary stars.

And just double-checking the numbers, I'm getting results that make no sense. Such as RAW garden worlds with so little atmospheric pressure, the water cannot condense.
?

What's the atmospheric pressure at which water cannot condense?

[cptbutton]

Originally Posted by David Johnston2

What's the atmospheric pressure at which water cannot condense?

Anything below 0.0060373 atmospheres.

The single combination of pressure and temperature at which liquid water, solid ice, and water vapour can coexist in a stable equilibrium occurs at exactly 273.16 K (0.01 °C) and a partial vapour pressure of 611.73 pascals (ca. 6.1173 millibars, 0.0060373 atm).

[Vaevictis Asmadi]

Yeah, that's the triple point.

But you need much higher pressures if the temperature is higher. RAW lets garden worlds get up to 340 K average surface temperature, at which you need at least 0.35 bars. (1 bar more or less = 1 atm)

But RAW lets a 340 K standard garden world get down to 0.137336 atm of air pressure.

It doesn't seem to be a problem at more Earthlike temperatures, but when fiddling with the system to create more exotic planets I want to make sure that the GM doesn't have to worry about ever getting numbers that won't work, no matter what they roll. I thought this pressure problem was just happening on worlds where I'd fiddled the numbers, but then I checked RAW garden worlds and got this.

I could have made a mistake myself, the equations are convoluted.


But regardless, I think I need to know what all the errors/errata are in the book before I create any custom planet types, or I'll design them all wrong.

[David Johnston2]

Originally Posted by Vaevictis Asmadi

Yeah, that's the triple point.

But you need much higher pressures if the temperature is higher. RAW lets garden worlds get up to 340 K average surface temperature, at which you need at least 0.35 bars. (1 bar more or less = 1 atm)

But RAW lets a 340 K standard garden world get down to 0.137336 atm of air pressure.

Have you though about what the temperature would be in winter at the poles?

[Vaevictis Asmadi]

Blarg, I was hoping I would get more help.

I don't even know how to calculate the temps at the poles, no. Glancing at the phase diagram for water, it'd need to be at most 325 K at a substantial part of each pole for the planet to have a biosphere based on liquid water, putting out all that O2.

Does ANYONE know what the errors in the Space world generator are? Or what thread they were discussed in? Please?

For example I know the luminosity for red giants is way off, but not what to change it to (real giant stars appear to vary by orders of magnitude in how much their luminosity increases, depending on their starting temperature, AFAICT).

Is my math on the Minimum molecular weight retained right?

And does anyone know where to get phase diagrams of things like pure methanol, ethanol, formamide, ammonia, water-peroxide mixes, and methane-ethane-propane mixes?

[Fred Brackin]

Originally Posted by Vaevictis Asmadi

Hi folks,
I've also wanted to make possible a wider range of primary stars.

I can't help you with the rest of your questions but perhaps if you explained your issue with this part I could do something.

[Vaevictis Asmadi]

The World Building sequence has rules for aging, temperature, and luminosity for stars of M7 to A5 spectral classes, which seem to be the most likely to host habitable worlds, and only abbreviated partial rules for other types of stars.

I came up with tables that allow a world-builder to get a star from M9 to B something, partly because I want to be able to generate stars for plasma life to live in, and I figure even B stars could be habitable for plasma life. Plus there are scifis where complex life evolves even on planets orbiting very dim M dwarfs or even brown dwarfs, so even if it's actually implausible I'd like the dimmer Ms at least as possibilities. I'd also like to be able to generate realistically detailed neutron stars for magnetic life.

So I want to be able to write an extended version of the table on p. 103.

But I don't know a lot about stellar physics, so I'm not sure where to go for info on (typical) luminosities, lifespans, temperatures, etc. for those types of stars, or for neutron stars. I've looked in some articles that I could find online and gotten some information piecemeal, though. But some of my info is just from Wikipedia which isn't ideal.

Also, I don't know if the luminosities in Space are bolometric or visible, where or when that would matter, or how to convert one type of luminosity to the other.

But part of it is that I'm essentially trying to "hack" the system to rearrange the order in which things are generated, but to avoid messing it all up I need a look "under the hood" and to know where the approximations break with reality.

[Humabout]

You might start with some of the more recent star cateloflgs and NASA's website for finding info. Otherwise, you'll need to just do some hardcore internet research. The info is mostly out there.

[Fred Brackin]

Originally Posted by Vaevictis Asmadi

The World Building sequence has rules for aging, temperature, and luminosity for stars of M7 to A5 spectral classes, which seem to be the most likely to host habitable worlds, and only abbreviated partial rules for other types of stars.

So I want to be able to write an extended version of the table on p. 103.

But I don't know a lot about stellar physics, so I'm not sure where to go for info on (typical) luminosities, lifespans, temperatures, etc. for those types of stars, or for neutron stars. I've looked in some articles that I could find online and gotten some information piecemeal, though. But some of my info is just from Wikipedia which isn't ideal.
.

Sorry, I can't answer any of your questions from myy long ago college courses in astronomy.

That leaves only internet research and you've already mentioned Wikipedia.

http://en.wikipedia.org/wiki/Stellar...Spectral_types

I can tell you from even briefly scanning this article that the frequency of B stars which was set at approx. 1 in 800 iis too low to have a whole number to itself on any 3D6 table. You'd need to do soemthign like take all rolls of 3 or 4 and then roll again on a sub-table with (for example) only rolls or 7 or less on the sub-table equaling a B.

This rarity was probably why B stars were left off the Space table along with their very short lifespans.

This seques into plasma life. I suspect that the thinking went that plasma life and other such exotics is so far out there that we can't even say what the probability of it would be. Therefore if you can't even guess at a probability you can't put it on a random table.

I will note that natural 3s and 18s are not actually that rare.

So you're probably on your own about exotic life.

I can speculate that if plasma li8fe were possible it would be more likely in the corona rather than at or below the photosphere. Magnetospheres of Jovian planets might be more likely than that.

Unfortunately, there's been little if any research on extra-solar coronas. I certainly can't tell you how they'd differ from the Sun's corona.

So at least with the big stars you're dealing with very low probability events and with the exotic life you're far beyond the realms of known science. Put this stuff in your games if like but you're going to be doing on an arbitrary basis one way or the other. <shrug> Just pick numbers you like.