Solar system generation

[IanBruntlett]

I'm hoping to run some adventures in the Spinward Marches (Vilis Subsector). There is information about world generation but I was wondering if the core rule book (or some other MgT book) gives guidance on how to generate a solar/stellar system? How many gas giants, how many planets, presence or absence of asteroid belt(s), orbital installations, presence or absence of moon(s)

 

[Fovean]

MGT Scouts has a simple system in the back of the book, useful for fleshing out solar systems, but it's quick-and-dirty without a large amount of detail.

My fave is GURPS Traveller First In but it's at the extreme other end of the complexity scale - and of course uses GURPS rules. But I love it for creating planetary systems around a detailed star (or stars) and it is pretty realistic for its time (my PDF is copyrighted 1999). Once I generate all the objects in their orbits I use MGT rules (slightly house-ruled) to detail everything.

 

[phavoc]

There was this post a while ago that talked about starsystem generators:

http://forum.mongoosepublishing.com/viewtopic.php?f=89&t=48728&p=690042#p690042

Looking at the ones in the links, I really thought that Utzigs interactive map was great.

 

[rust]

For only a few USD you could download the PDF of the
Classic Traveller version of the Scout book:

http://rpg.drivethrustuff.com/product_info.php?products_id=80174&filters=0_0_0_0_40050

The results of its system and planet generation rules
are almost 100 % compatible with Mongoose Travel-
ler. Some of its astronomical assumptions are slightly
outdated (well, plain wrong), but so are the ones used
to design the Spinward Marches, and so this does no
harm.

 

[IanBruntlett]

I've looked through "World-Building" (Stephen L. Gillet), Wikipedia (solar system etc).

Then I had a distance memory of a GURPS book lurking on a bookcase. Had a look, and yes, I have a copy of GURPS Space (2e). Looks interesting enough so I've started reading up on that. With 26 solar systems in Vilis subsector, I'll be creating planets on an industrial scale

 

[Hans Rancke]

Try googling for writeups of the worlds first. Even if there are no official ones, you could get lucky and find that some fan has already done the work.


Hans

 

[GypsyComet]

Prior editions have established the basics, in terms of how many gas giants and planetoid belts are present, and what the star's type is. For the star type I'd use the TNE version of any published sector (for TNE that includes the Marches), as TNE corrected a couple early misconceptions about star types and their frequency, and relegated most dwarf stars to companion positions in the interest of having livable worlds in this big space opera of ours.

For example, you'll see a line like this:
Vilis 1119 A593943-A Hi In 820 Im G5 V M8 D

The '820' indicates the population multiple (8 billion people in this case), the number of planetoid belts in-system (two), and the number of gas giants (none). Planetoid belts are *in addition* to an Asteroid belt main world, should that be the case.

This system is a binary, with a mid-yellow main sequence star (Sol is a G3 V), and a late, cool, red dwarf companion.

The relationship of the two stars is not defined, and could be anything from close (orbit zero, basically) to a far companion (potentially has its own planets, burnt out rock balls though they may be) or anything in between.

The above line is pulled from the TravellerWiki, by the way, which, being a Wiki, is suspect. In this case, the data for Vilis matches the MegaTraveller data, and the stars are not the type that would have seen a TNE revision.

 

[IanBruntlett]

MGT Scouts has a simple system in the back of the book, useful for fleshing out solar systems, but it's quick-and-dirty without a large amount of detail.

I've had a quick look in my copy of Scouts and can't find the system you mentioned. Could you give me some page numbers please

 

[rust]

See pages 92 and 93, but it is really a rather simplistic
mini-system.

 

[IanBruntlett]

Thanks Rust

 

[captainjack23]

Hi,

The system in question (in scouts) is only intended to give a chart of the system, not a map, so it may not be what you need. For instance, all orbits are relative to each other (no hard numbers), and the main goal is to place the main planet/starport in relation to other planets; very little attention is paid to granular details of the other planets beyond a basic type. Basically to give a traffic map to a commercial or private navigator or a quick fiddle for GMs in a seat of their pants situation.



Nice to see it mentioned, though !

Cap
(who wrote it for scouts)

ps, the idea of including a detailed world & sysgen system were floated, but it was too much to do right given the allowed page count, and was .....somewhat a heated issue at the time.

I could probably post some of the stuff I developed for that if there is interest....and a lack of drama

 

[rust]

I would be interested, and there will certainly be no drama
caused by me. :wink:

I am well aware that any attempt to create such a system
which is "scientifically correct" would take a book, that this
book would deliver results which would not fit in well with
the existing Traveller "canon", and that this book would pro-
bably be outdated in less than a year anyway.

So, all one can hope for is a system which creates results
which are plausible within Traveller's "canonical" framework,
covers all the data needed for the game, and has no internal
contradictions.

 

[IanBruntlett]

Hi Cap,

ps, the idea of including a detailed world & sysgen system were floated, but it was too much to do right given the allowed page count, and was .....somewhat a heated issue at the time.

I could probably post some of the stuff I developed for that if there is interest....and a lack of drama

Yes, I'd love to see it. Perhaps it could be a download on the Scout's book's web page - http://www.mongoosepublishing.com/rpgs/traveller/core-rulebooks-accessories/book-3-scout.html


Ian

 

[Fovean]

Yes, would love to see those notes, too!

I hope I didn't come across as dismissive, as I said the GURPS system is a bit too far the other way for me... it'd be great to find a happy medium of crunch and ease.

Once that's done we can cure cancer and end hunger :wink:

 

[Hopeless]

Got pointed towards Gurps Space 2nd edition which helped but I was able to pick up a copy of Traveller the New Era which has just such a system included if that helps.

Sorry forgot to ask is Vilis expanded upon in the library database or has an adventure based there which might have more details on the system?

 

[rust]

Sorry forgot to ask is Vilis expanded upon in the library database or has an adventure based there which might have more details on the system?

The Classic Traveller adventure Broadsword takes place on
Garda-Vilis and has a little (really, only a little) information
about Vilis, too. Otherwise I am not aware of any adventure
with a connection to Vilis.

The Traveller Wiki has this:
http://traveller.wikia.com/wiki/Vilis_(world)

 

[IanBruntlett]

I'm using Scout (Mainworld Cartographic System - page 93-93).

Just tried out Method I : Standard Orbit. Looks OK but I'm missing one thing. What are the distances between orbital bodies? I generally need to know this because I need to know how long it takes to get from one orbit to another.

 

[rust]

This is where things tend to become complicated, because the
actual possible orbit of a planet in the habitable zone depends
on the luminosity of the system's star(s), the planet of a faint
dwarf star orbits its star much closer (and is probably tidally
locked) than the planet of a bright giant star (which would of-
ten be too young to be truly habitable).

If you want plausible orbits and distances between orbits, you
will have to use a more detailed system, somewhere between
Classic Traveller's Scout book (comparatively simple, but with
results based upon outdated astronomical assumptions) and
GURPS Space 4e (very realistic and detailed, but rather com-
plicated to work with).

 

[IanBruntlett]

This is where things tend to become complicated, because the
actual possible orbit of a planet in the habitable zone depends
on the luminosity of the system's star(s), the planet of a faint
dwarf star orbits its star much closer (and is probably tidally
locked) than the planet of a bright giant star (which would of-
ten be too young to be truly habitable).

I tend to run Traveller sessions as games rather than simulations. So an average distance between orbital bodies would be more than enough for me. I've got a suitable table of our solar system from Wikipedia (List of gravitationally rounded objects of the Solar System).

 

[rust]

So an average distance between orbital bodies would be more than enough for me.

Unfortunately there is no such thing as an "average
distance between orbital bodies", it depends on the
type of the system's star(s). All you can get is a ta-
ble with average distances depending on the star ty-
pe. I will try to find and copy such a table from an
earlier version of Traveller, and to post it here.