Habitable Moons of Gas Giants?

[lspitz]

I vote for the Fun Factor and GM fiat.

The first mention of a GG moon being inhabitable that I recall was Heinlein's Farmer in the Sky written in the early 50's for teens. Even then the terraforming of Ganymede required a heat shield of some sort to hold in the heat. That book had a Fun Factor when I was young.

Honestly, without the enjoyment of role playing and tweaked systems, 99.9% of the planets in any Traveller universe would be unihabitable, and the percentage of moons would be worse.

True, but the world-building rules in Traveller do very well at recreating the feel of Golden and Silver Age of SF. Since that's what I grew up reading, it made the game very attractive to me. Science has moved on since then, so anybody who wants a Traveller game set in an accurate-looking reflection of the universe as it's currently understood is going to have to do some major sysgen tweaking.

I do love older, less realistic settings for the space-opera feel of them. At this point they really have to be considered fantasy (sciencey-feeling fantasy, but fantasy nonetheless). It depends on my mood as to which approach I want to take- I can certainly be happy playing a science-fantasy sort of game if the background is interesting and reasonably self-consistent/true to its own internal logic.

Lately, I've been exploring rule tweaks to introduce more realism, just to see what happens. Most of the process has to be kept out of sight of the players; they get presented with the finished starmap and the UWPs and don't have to know anything about how things got generated.

But sometimes, you know, you just want to throw out all the constraints and explore the canals and ancient ruins on a Mars that never could have been.

 

[rancke]

I vote for the Fun Factor and GM fiat.

So do I, but it's not a dichotomy. I'd rather have an implausible fun system than a plausible boring one; but I'd rather have a realistic fun system than an unrealistic fun system. I like my orbital periods and temperatures to have a fair degree of verisimilitude, and I've yet to come across a system where such verisimilitude has affected the fun factor negatively.


Hans

 

[SpaceBadger]

I've been through the literature. Current real-world science does support the idea of habitable moons of gas giant planets. It gets complicated, but you can pluck out some rules of thumb:

*snip*

So current science thinks they're possible, with certain caveats.

Thanks. That is pretty much what I was getting, but it is nice to have independent confirmation.

 

[SpaceBadger]

An old brown dwarf is a "Brown Duffer".

:rofl: Works for me!

 

[aramis]

Uh, brown duffer would be an African bad golfer, not an old dwarf.

 

[Carlobrand]

Verisimilitude is always to be striven for, but there's one rule that always needs to be remembered: you are under no obligation to explain to your player why this thing works that way unless it is integral to the adventure and their skill set suggests they should have that information. It may be stunningly inexplicable, but for the denizens of that universe, the fact that it's staring them in the face is proof enough that it can happen; only the scientists will be concerned with how it happened, and often they'll only have the vaguest idea themselves. If the players really, really want to know, they can hire an expert or go to the local library and make an adventure of getting their questions answered. Even in a TL15 society, there'll be the occasional, "Gee whiz, we just aren't really sure, but we think..."

Realism helps build atmosphere, but it should not restrain you from making something really memorable. In a universe where ancient powers occasionally played God with species and planets alike, and where the systems in question may range in ages from very young to on-the-verge-of-going-nova, there's quite a bit that's fair game. Where would sci fi be without a Ringworld?

 

[SpaceBadger]

So do I, but it's not a dichotomy. I'd rather have an implausible fun system than a plausible boring one; but I'd rather have a realistic fun system than an unrealistic fun system. I like my orbital periods and temperatures to have a fair degree of verisimilitude, and I've yet to come across a system where such verisimilitude has affected the fun factor negatively.

Yeah, what Hans said. Verisimilitude doesn't require absolute scientific accuracy, but it does require something that seems real enough that it doesn't take me out of the story, shaking my head and thinking, "No way!" :file_28:

Sure, we have FTL drives and maybe gravitics and such, but once those are accepted as part of the story, the rest should at least try to seem real enough not to break the immersion.

 

[HG_B]

Verisimilitude is always to be striven for, but there's one rule that always needs to be remembered: you are under no obligation to explain to your player why this thing works that way unless it is integral to the adventure and their skill set suggests they should have that information.

Sorry but, by all indications, my players have IQ's >50. They ASK when a planet with no atmosphere and at TL3 has 40,000,000 people living on it, how that is. If I read them the above they'd rightly toss me out of the room.

YMMV depending on your players attention to the game world/universe.

 

[lspitz]

So do I, but it's not a dichotomy. I'd rather have an implausible fun system than a plausible boring one; but I'd rather have a realistic fun system than an unrealistic fun system. I like my orbital periods and temperatures to have a fair degree of verisimilitude, and I've yet to come across a system where such verisimilitude has affected the fun factor negatively.


Hans

That's very much how I feel. Fun is paramount, but realism is highly preferred. When I can't have strict realism, I value internal consistency. I abhor game mechanics of any sort, realistic or not, that are tedious and bog down play.

Specific SF subgenres get a special dispensation from me because strict realism doesn't suit them, and indeed ruins the mood. If I want to play a 1930s-style game with habitable planets and a native intelligent species in every star system, I'm not going to worry about scientific realism. Escapism is fun from time to time.



Anyway, we've strayed pretty far from the original topic posted by SpaceBadger. In a realistic game, habitable moons will only occur around really big gas giant planets (retired brown dwarfs) of 15 Jupiter masses or greater, and these giants will appear at a frequency about a quarter that of 1-Jupiter mass planets.

For a bit of color, literally, a gas giant that hosts a habitable moon will probably be a Sudarsky Class II or III. If Sudarsky is correct, it'll be blue, or faintly banded blue-and-white, and won't look very much like Jupiter. It will tend not to contrast strongly with a blue nitrogen sky as seen from its moon, so it'll be impressive, but much less spectacular than one might think.

 

[Carlobrand]

Sorry but, by all indications, my players have IQ's >50. They ASK when a planet with no atmosphere and at TL3 has 40,000,000 people living on it, how that is. If I read them the above they'd rightly toss me out of the room.

YMMV depending on your players attention to the game world/universe.

So do mine, but:
1. they also understand what it means to roleplay;
2. a planet with no atmosphere and 40 billion souls has a +5 to tech level, ergo a minimum tech level of 6, so if this place is actually TL3 then it's by my invention and I have a plan and a method to my madness that the players will have to figure out as they play. Answering their questions at the outset is likely to tip my hand and spoil the adventure.

My favorite response to a player who says, "That's impossible," is, "Yes, yes it is. And yet, there it is. Now you figure out why."

 

[HG_B]

2. a planet with no atmosphere and 40 billion souls has a +5 to tech level, ergo a minimum tech level of 6,

My favorite response to a player who says, "That's impossible," is, "Yes, yes it is. And yet, there it is. Now you figure out why."

I didn't say BILLION. Anyway, like I said, being cheeky because I don't want to do the work necessary to GM would mean my players walking.

 

[Carlobrand]

I didn't say BILLION. Anyway, like I said, being cheeky because I don't want to do the work necessary to GM would mean my players walking.

Oopsie! You're right, my bad. However, I don't recall saying anything about being cheeky or lazy. If one is lazy, the players should walk. On the other hand, if they don't trust you enough to play in what you offer without a lot of up-front debate, you got another kind of problem going on. I'm perfectly willing to take criticism afterward - goodness knows, this alone shows I'm as vulnerable to mistakes as the next guy, and I get my share of, "Oh crap," moments. Willing to accept a redirect during, if they spot me in some mistake like forgetting that the world they're on has a shorter horizon or that they can carry more in light gravity, or if some key oddity is a matter of life and death. Otherwise, if they don't trust me to give them a good game, then best we reconsider the relationship; might be happier all around if I roll up a character and let the other guy run the game.

Here's a test: give them a little planetoid with an earth-normal atmosphere and gravity. If they want to argue with you about it, you got a problem. If they want to start taking measurements and try to figure out how it's doing that, hoping maybe they can make some money off of it, then you've got a good roleplaying group going.

 

[HG_B]

Here's a test: give them a little planetoid with an earth-normal atmosphere and gravity. If they want to argue with you about it, you got a problem. If they want to start taking measurements and try to figure out how it's doing that, hoping maybe they can make some money off of it, then you've got a good roleplaying group going.

Of course you're right. I meant throwing the junk at them like what is produced by Trav's world generation system and telling them to be quiet when they question the inanity of it.

 

[Carlobrand]

Of course you're right. I meant throwing the junk at them like what is produced by Trav's world generation system and telling them to be quiet when they question the inanity of it.

I agree, that would be both cheeky and lazy. Better to apply one's own ingenuity and then let the players apply theirs - but if it's just not workable, it might be best to just say that the scout who fed that report into the system was eventually fired for gross incompetence and alcohol abuse on duty, then make up your own figures that make sense.

 

[HG_B]

I agree, that would be both cheeky and lazy. Better to apply one's own ingenuity and then let the players apply theirs - but if it's just not workable, it might be best to just say that the scout who fed that report into the system was eventually fired for gross incompetence and alcohol abuse on duty, then make up your own figures that make sense.

I had to do that so often that I dumped Trav's world gen system decades ago. I'd rather have, by default, worlds that make sense. And THEN I can go through and make "special" or odd ones as exceptions. The current rule set has it bassackwards.

 

[Fritz_Brown]

I've already posted about this issue in the past complete with corrections, etc. in my alternate UWP procedure.

Link, please?

Correct, detailed, quick: Pick two.

Heh.

My favorite response to a player who says, "That's impossible," is, "Yes, yes it is. And yet, there it is. Now you figure out why."

I like that one, too.

Here's a test: give them a little planetoid with an earth-normal atmosphere and gravity. If they want to argue with you about it, you got a problem. If they want to start taking measurements and try to figure out how it's doing that, hoping maybe they can make some money off of it, then you've got a good roleplaying group going.

Excellent point!

 

[Carlobrand]

I had to do that so often that I dumped Trav's world gen system decades ago. I'd rather have, by default, worlds that make sense. And THEN I can go through and make "special" or odd ones as exceptions. The current rule set has it bassackwards.

Since I generally stick to the Marches, it's more a case for me of identifying the headaches and then deciding what to do about them.

 

[HG_B]

Since I generally stick to the Marches, it's more a case for me of identifying the headaches and then deciding what to do about them.

I did that 'till about '82.

 

[Ishmael]

Link, please?

the relavent post

http://www.travellerrpg.com/CotI/Discuss/showpost.php?p=403590&postcount=36

 

[Fritz_Brown]

Thank you! That's some good info. Did you realize you're doubling up on the influence of the Temp Multiplier when you do hydro? Since it's already in the atmo calculation, which is used in the hydro caclulation.