Space 4e System Generation

[MrId]

What do people think of the new system generation rules in Space 4e?

I rolled up a system this morning, although it seems to my (limited) knowledge more scientifically accurate than most other systems I've run into. I only defined physical parameters for the system (an M7 Ve star with 4 gas giants (one epistellar), no terrestrial planets, no asteriods and 3 moons bigger than moonlets), and not social parameters yet, but those actually look quite easy. The only problems that I ran into was the headache I got while trying to generate planetary diameters for the moons (I think I got it right eventually), and trying to get the planetary orbits right. Up until working out the diameters I was stunned at how much simpler the system was compared to First In, but still more than adequate for gaming purposes. I think once I get that down I'll be in better shape.

I might try a few more tonight once (I have a red dwarf binary, another flare star, and G1 V/White Dwarf pair in the pipeline...) and see if I can get a habitable planet or more variation.

What are other peoples experiences? I'm curious as to what other people are doing with this part of the book...

[Big Bear]

I'm going to turn it into an Excel spreadsheet in an attempt to ease my throbbing brain. It's an awful lot of detail...

When I was cooking up my first set of aliens, they were basically "people in funny suits". With the environmental/biological modifiers for social interaction, my next set of aliens will work MUCH better.

[MrId]

I use Excel to chug through the formulae, but my Excel-fu isn't strong enough to really make a general purpose template (or whatever they're called...) There are so many variables that I just find it easier enter the values on my own.

I hadn't though of the alien generation stuff yet. I had planned on cribbing aliens from Traveller, Uplift and GURPS Aliens, but perhaps I will try and cook up some unspeakable strangnesses myself...

[Pomphis]

Originally Posted by MrId

What are other peoples experiences? I'm curious as to what other people are doing with this part of the book...

I like it. I rolled up several systems. I made an excerpt with just the tables, and rearranged them somewhat. For example I integrated the table where one rolls for mass with the table which gives data for the mass. I also split it into three seperate parts: Star & System, Gas Giants and Moons, Terrestrials and Moons. That way it becomes a lot more handy.

I believe the Brown Dwarfs have a mass that is too large by a factor of 10, the given values would put them in the same range as K- and M-stars.

[Rupert]

Originally Posted by Pomphis

I believe the Brown Dwarfs have a mass that is too large by a factor of 10, the given values would put them in the same range as K- and M-stars.

I wondered about that too.

[dataweaver]

I've instituted a "house rule" of sorts for placing planetary orbits in order to simplify the math: any time that orbital position and blackbody temperature interact, I determine orbital position relative to the Snow Line instead of using the star's luminosity. The relationship that I use is:

(orbital radius / snow line radius) = (126 Kelvins / blackbody temperature) squared.

(Why 126 Kelvins? Because that's the temperature that I get when I plug the Snow Line radius into the formula in step 25. I'm seriously considering using 125 Kelvins instead, since it's a nicer number and I doubt that one Kelvin out of 126 will trash the system.)

Step 21, placing a predesigned world: R = (126/B)^2 * Rs
Step 25, blackbody temperature: B = 126 / square root of (R / Rs)
(In both cases, Rs = snow line radius.)

World Type Assignment Table: I pencilled in a column giving appropriate orbital radii as percentages of the snow line radius.

I've replaced the luminosity-based Inner Limit with 0.2% of the Snow Line radius. It requires computing the Snow Line before computing the Inner Limit; but that's not a major problem IMHO.

I'm also inclined to say that not even epistellar gas giants can exist inside the luminosity-based inner limit. Incidently, this also places a hard upper limit of planetary blackbody temperatures: 2800 Kelvins.

I'm looking into guidelines for climate variations based on day vs. night, using the Tide-locked world rules as limits. My problem lies in figuring out how long a day can be before the limits are hit. I'm also interested in computing lattitude-based variations; while I know that there ought to be a simple formula for this, I don't know what it would be.

[Pomphis]

Originally Posted by dataweaver

I'm looking into guidelines for climate variations based on day vs. night, using the Tide-locked world rules as limits. My problem lies in figuring out how long a day can be before the limits are hit. I'm also interested in computing lattitude-based variations; while I know that there ought to be a simple formula for this, I don't know what it would be.

I have some stuff which I copied somewhere, maybe Space 2e:

Average Temperature is up to two levels hotter at the equator, up to four levels colder at the poles.
Summers are one level hotter per 18° axial tilt, winters are one level colder per 12 ° axial tilt, but effects are felt only starting from the poles, with larger tilts affecting larger areas.
Days are one level warmer and nights are one level colder per 40 hours rotation, rounded up, up to a maximum of 5 levels.
Oceans damp nearby variations one level.

(Levels are the temperature bands defining "Cool" or "Tropical".)

2e also had rules to determine a Weather Factor, which influences how massive weather changes are.

[MrId]

Originally Posted by Pomphis

I believe the Brown Dwarfs have a mass that is too large by a factor of 10, the given values would put them in the same range as K- and M-stars.

I had noticed that didn't seem right either, but I wasn't sure if it was a consistantly misplaced decimal point or something else. Hopefully errata will be forthcoming.

[MrId]

Originally Posted by dataweaver

I'm also inclined to say that not even epistellar gas giants can exist inside the luminosity-based inner limit. Incidently, this also places a hard upper limit of planetary blackbody temperatures: 2800 Kelvins.

I'm not sure about that -- haven't large gas giants been detected very close to thier primaries in other star systems? I think they can survive there if they formed further out and have sufficient mass to keep their atmosphere despite the increased heating, but I'm decidedly not an astrophysicist.

Originally Posted by dataweaver

I'm looking into guidelines for climate variations based on day vs. night, using the Tide-locked world rules as limits. My problem lies in figuring out how long a day can be before the limits are hit. I'm also interested in computing lattitude-based variations; while I know that there ought to be a simple formula for this, I don't know what it would be.

I have largely the same stuff from First In, so I'll just but a couple additional notes in:

Adding to what Pomphis wrote, for latitude based variation, the planets "average" climate zone should be in hex rows 4-5 (on the old icosahedral map), while rows 2-3 will be one categories warmer, while the equator will be two categories warmer. Repeat the same sequence heading towards the poles (6-7 one cooler, 8-9 two cooler, 10-11 three cooler, and 12-13 four cooler). While the book (First In) doesn't say either way, I think that this requires a substantial atmosphere to work and distribute the heat evenly. Of course, if there isn't an atmosphere, the PCs will probably have problems other than the temperature...

For seasonal variation, the only thing that I would add is, according to First In, axial tilts of 40 degrees or more will affect temperature to some degree all the way down the equator, while planets with 25 degrees of tilt would have "full seasonal effects" in rows 7-13, but not so much below that. I found that with First In I generated a lot of planets with high axial tilts, which would probably cause all sorts of headaches for settlers trying to do any sort of agriculture.

[Flyndaran]

Has anyone else noticed that the text on page 84 says to divide the average temperature by the black body correction makes no sense?

Doing it that way makes high greenhouse numbers COOL the planet.
A pretty glaring error.

Can someone confirm this just in case I've lost my mind, please.