Is the world generation system messed up?

[Slink182]

OK, I wrote a little program to generate subsectors according to T20. However, Flynn and others have pointed out that there appears to be an overabundance of mainworld asteroid belts. Checking my code versus the rules, I didn't find anything programmed wrong, but checking the rules and running some statistical numbers showed that the T20 system generation/world generation rules WILL create a lot of asteroid belts. The full description can be found at the following forum link, post #5:

http://www.travellerrpg.com/cgi-bin/Trav/CotI/Discuss/ultimatebb.cgi?ubb=get_topic;f=51;t=000038

I need comments and, if possible, a fix for this issue (preferable an "official" fix). People are of the mind that there is either a problem with the star size distribution, the habitable zone assignment, or both.

 

[Flynn]

Here is a suggested fix:

Ignore the references to modifiers that decrease size based on Orbit number.

Rationale: we are learning more and more that other solar systems do not conform to our previous theories of even ten years ago. For example, our astronomers have located large gas giants closer to their primary than the Earth is to the Sun. For consistency's sake with 25+ years of prior Traveller sector generation, I'd be very much in favor of dropping the above modifiers and just moving forward from there.

My two Credits,
Flynn

 

[jwkrlb]

hi,my first post, i end up with way too many
red darws stars, when i use that program.
i just the t20 book yesterday.

 

[Flynn]

Welcome aboard, jwk,

I think that Slink is exploring other options right now, and hopefully will come up soon with something he likes. (I'm personally hoping for a configuration setting that allows you to turn off the Orbit modifiers if that's your desire.)

Looking forward myself to seeing what the next version holds,
Flynn

 

[Malenfant]

Well, book 6 actually says (on page 33, step 4C):

"If size 0-, use S"

I dunno if T20 has that, but S is the size code for a world that is a couple of hundred km in diameter (it says 200 km, but I just assume it's less than 500 miles (800 km) in diameter).

So if you use that, you'll have an over abundances of tiny rockballs in close orbits, which may be a bit more reasonable.

Using the basic UWP system from book 3 or 6 doesn't factor in orbit position or star type, so it's possible to generate worlds that don't agree with the Type M limitations despite the fact that the planet orbits one.

 

[Flynn]

Malenfant,

Size "S" is not used for Mainworlds, only for secondary worlds.

I'm wondering if there is unrecorded errata on that, in that the size modifiers only apply to non-Mainworld planetary bodies? I think that's more in keeping with CT's Book 6.

-Flynn

 

[Malenfant]

(I'll carry on this discussion here)

True if you use the basic or continuation charts in book 6 - but if you use the extended system generation charts in book 6 it doesn't actually say that size S can't be used for a mainworld.

There could be a RW reason for asteroid belts in close orbits around M V stars though. Their frost lines - beyond which you'll get volatiles dominating the protoplanetary nebula which allows gas giants to form more easily - are going to be much closer to the star than for more massive stars. Jupiter's gravitational influence managed to prevent a planet forming 2 AU closer to the sun than its orbit (thus forming our own asteroid belt) - a similar (or more massive) jovian in anything up to a circular 2 AU orbit around an M V star would probably also prevent planets forming anywhere inside its orbit in the same way. Thus you'd get lots of asteroid belts.

 

[Flynn]

Hehehe. I'm leary about citing Real World (tm) information on solar system generation, given that what we know about their construction has changed dramatically between the release of CT and the release of T20.

For me, at this point, it's a matter of consistency with UWP data from previous versions of the game, at least in the OTU. (For a homebrew ATU, that's a different matter altogether.)

While Book 6 may not say that size S can't be used for a mainworld, the fact that I haven't seen any published as Official products tends to make me think there's an unwritten rule on the subject.

-Flynn

 

[Malenfant]

Two things...

First, T20 isn't (from what I recall - my copy is back in the UK) much more realistic than the CT generation system, if at all.

Second: I don't think there's an unwritten rule against Size S mainworlds, as much as inconsistency in the CT world generation system - namely that the expanded generation charts don't produce results that tally with the basic or continued generation charts. Ideally, I think the expanded chart should be used to generate the mainworld UWP (and the rest of the system), but because the CT sector books came out before Scouts the point is moot anyway, since the book 3 generation system was used for both. Before book 6, small worlds below size 1 didn't even exist in the OTU, then suddenly they were everywhere.

On a separate note, I wonder what happened to worlds that should have had the D/E/F atm types in the Spinward Marches. They didn't exist in book 3, and were actually (I think) first seen and defined in the Solomani Rim book before Scouts came out. So what atmospheres were allocated to the size 8/9/A worlds in the Marches if they rolled high enough to get above atm C? Was it just set to C instead (which would mean there are more C atms than there really should be in the Marches)?

 

[jwdh71]

I'm currently working on the third subsector of the four that I will be doing for my current campaign, and I am using T20 rules. With the expanded system generation you have to creatively edit the information you get from it to make systems that are at all worthwhile from a habitability standpoint. Every system that ended up with a population had to be fudged in one way or another, and I am putting populations in less than half the systems, as this is a frontier area. T20 system generation is like its distinguished predeccessors, in that it needs to be gently guided by the Referee to get anything near what you want. At this point I'm not using the modifiers for M class stars, and not using the full modifiers for planets in orbits 0,1, or 2. If any LGGs (Large Gas Giants) end up in the inner system, the next orbit in has any planetoid belts there might be. This seems to work for me, but as I said, I have to gently guide this system along to get anything worthwhile. Sigh.

 

[Slink182]

I was afraid of that, John... . So far, some back-of-the-envelope calculations show that, statistically, producing CTU type subsectors/mainworld distributions are next to impossible. I keep going over the T20 system, and its just, IMO, "broke".

As it stands, red dwarfs appear ~75% of the time, and that practically drives asteroid belt mainworlds to the 50% occurrence threshold. The orbit location (0) and size (0) further drives Atm and Hyd such that there are a lot of vacuum and desert worlds also. *sigh*

 

[Malenfant]

According to CT book 6, the probability of getting an M V primary should be about 56% if the mainworld isn't habitable and already generated, or only 8% if it is habitable and already generated.

According to the Regency Sourcebook, only 24% of the stars in the Spinward Marches are M V. I don't know if that's because the modifier for primary size/type has already been applied there though (it's also +5 in TNE, instead of +4 in CT).
For all I know, the TNE data could have been taken from broken GENIE UWPs - in which case even the CT data for the Marches doesn't agree with the stellar distribution that Book 6 implies.


Also, 27% of the stars there are white dwarfs, which is ludicrous. White Dwarfs shouldn't be anywhere near that common - they are the cores of massive stars (1+ solar masses) that have died, and only about 15-20% of all stars are massive enough to become WDs, and only a small fraction of that number would have actually become a WD by now (the rest would still be "alive" as type V or III stars).

Realistically, about 71% of stars should be M V. In that regard at least, T20 is better.

 

[jwdh71]

I agree that T20 system gives a more reasonable amount of M V stars, but to get the same proportions of habitable worlds as there are in Traveller canon, you have to do a little creative juggling when using the system generation rules. And in any one area, there will be quite a few systems that should logically have little or no population, as there is really nothing in the system that begging to be exploited, either in mineral wealth or habitable planets.

Now, this works for my current campaign, as I am doing a frontier patrol campaign, so empty systems all over the place for pirates and smugglers to hide in, and for intrepid patrol crews to hunt for said pirates and smugglers in, is a good idea. But if I was doing a more standard Traveller campaign, trying to make populated sectors of space is much more difficult. I thought of a solution that might work, simply generate more systems. By that I mean if you have a sector that is Sparse, you actually roll vs. Standard on the table, i.e., 4+ on 1d6 for a system, Standard would roll as Dense, 3+, and Dense would roll 2+. All barren systems would be marked as such, or even left off most maps, as they don't see any traffic unless they are a link to a main. On previously generated sectors that don't have enough M V systems, simply add them into empty hexes until the percentages make more sense. In populated areas, these barren systems will be mostly ignored, and the Navy and Scouts will seed them with passive and active sensor platforms, and occansionally patrol them, or use them for exercises. IMTU (OTU version) these are the only systems that the Imperium actually "owns", in that no one else uses them, or even has legitimate reasons to go there. In between missed red dwarves, and brown dwarves, an actual hex map of a Traveller sector should have almost one star per parsec.