Doc Posted December 14, 2007 Report Share Posted December 14, 2007 Hi, I've been thinking about a hotshot spacefighter pilot game, a la Battlestar Galactica (the new serie), for a while. My main bug was to create a realistic setting in wich several planets would be habitable. The idea is, as I wanted it to fit physical laws, I didn't want to include FTL travels. It's been a long and hard work, but here I'm am sharing the result with you. I hope this can be usefull to someone else, too. Of course, feel free to tell what you think about it... So there it is. As there is no FTL travel, all the planets have to be in the same solar system (as even at half the speed of light, it would be eight years to go from Earth to the nearest star system, Alpha Centauri, while it only takes 6 hours and a half to the light to go from the Sun to Pluto...). Moreover, to be really realistic, I choose to limit the speed of the spacecrafts to one tenth the speed of light (wich is still a tremendous speed...). Another problem is, a star system canno't realistically support a dozen of habitable planets. So here's how I solved this. First of all, the star system would be a binary star. Binary systems can have their stars as "near" as a hundred AU (the distance between the Sun and Earth; Jupiter is at five AU from the Sun, and Pluto, at forty). Two stars orbiting one around each other at a distance of a hundred of UAs offer the possibilitu to double the amount of planets in the system and to have both planetary system nearly "touching" one another, wich also makes traveling more reallistic. Then, both stars have a habitability zone wich are each orbited by two planets (yuy, is it clear? ). Anyway, each star has two planets in its habitability zone. To maximise the number of habitable planets, two of those planets are gaz giants (one around each star). Gaz giants aren't habitable per see, but their lerger moons could be. If each gaz giant has four habitable moon, then we're up to a total of ten confortable, habitable planets... You can add to this a couple of planets where there is small human settlements, but no expensive colonisation due to harsh conditions (slightly too hot or too cold, no atmosphere, etc). Life there is only possible in stations. Floating stations are also possible in gaz giant planets. Stations could also be possible on the fringe between day and night of tidal locked planets too near of a star. Tose places would only be colonised for ressources exploitation, nuclear wastes disposal, etc. Voilà! You have a star system with numerous worlds wich are inhabited by a wide variety of people. In the worst case, at ten percent the speed of light, it would take less than fifty days to travel between the two fartest orbiting planets when they are totally opposed in their revolution cycles (to go strait through one side to the other of the binary system). Ouf! Am I nut to think about this during HOURS and to take nearly one to write this here??? Quote Link to comment Share on other sites More sharing options...
Lysando Posted December 14, 2007 Report Share Posted December 14, 2007 Re: Setting for a "realistic" campaign in space Coupla questions: At a distance of 100 AU, what would be the effect of the stars gravity on eachother? Is that close enough that their gravity would be trying to suck matter from eachother, and also maybe skewing the orbits of the planets? 4 habitable moons around a "gaz" [sic] planet seems awful high...When you say "habitable", do you mean in the sense that people live in an enclosed settlement/base, or as in having a breathable atmosphere so people can live there without air tanks? Quote Link to comment Share on other sites More sharing options...
Bygoneyrs Posted December 14, 2007 Report Share Posted December 14, 2007 Re: Setting for a "realistic" campaign in space OK with a Binary star system, with a major and minor star I would advise designing the system as follows: Primary Star system (2) planets with atmospheres that humans can breath, make one a perfect Earth like duplicate, and the other slightly different and requires a resperator because of lower oxygen levels. Maybe the 2nd planet is Dune Like, Or Frozen in Ice, or Water world...but make it different. Secondary Star System (1) Moon around a Large gas Giant , not a perfect world but breathable atmosphere, and the other planet is a Mars like world with a thicker atmosphere and running water and some plant and animal life as well too. Thus you would have (4) planets, and then the rest of the worlds (planets/moons) might have bases and/or colonies on them. The next question is, are you using humans and No other Intelligent Alien species. Two different races could have developed in those different systems and etc. Penn Quote Link to comment Share on other sites More sharing options...
Clonus Posted December 14, 2007 Report Share Posted December 14, 2007 Re: Setting for a "realistic" campaign in space I think you've overdone it a little. Having the two systems have the identical setup makes things look artificial. I'd suggest having A have two planets in the habitable zone while B had the gas giant in the habitable zone. Quote Link to comment Share on other sites More sharing options...
Doc Posted December 14, 2007 Author Report Share Posted December 14, 2007 Re: Setting for a "realistic" campaign in space Coupla questions: At a distance of 100 AU, what would be the effect of the stars gravity on eachother? Is that close enough that their gravity would be trying to suck matter from eachother, and also maybe skewing the orbits of the planets? Probably not if they are, let's say, red dwarves. Red dwarves still have a habitable zone; it's just nearer of the star. 4 habitable moons around a "gaz" [sic] planet seems awful high...When you say "habitable"' date=' do you mean in the sense that people live in an enclosed settlement/base, or as in having a breathable atmosphere so people can live there without air tanks?[/quote'] No, I meant habitable without difficulties, like on Earth. Both Jupiter and Saturn have four large moons. I just thought that those planets could have a little more, like five or six, and then, that four of them could be habitable. OK with a Binary star system, with a major and minor star I would advise designing the system as follows: Primary Star system (2) planets with atmospheres that humans can breath, make one a perfect Earth like duplicate, and the other slightly different and requires a resperator because of lower oxygen levels. Maybe the 2nd planet is Dune Like, Or Frozen in Ice, or Water world...but make it different. Secondary Star System (1) Moon around a Large gas Giant , not a perfect world but breathable atmosphere, and the other planet is a Mars like world with a thicker atmosphere and running water and some plant and animal life as well too. Thus you would have (4) planets, and then the rest of the worlds (planets/moons) might have bases and/or colonies on them. The next question is, are you using humans and No other Intelligent Alien species. Two different races could have developed in those different systems and etc. Penn I planned to put only human beings in this setting. The reason why I wanted so much habitable planets is that I wanted to reproduce the feeling of the twelve colonies in the Battlestar Galactica pilot. We could say that the planets were originally in the form you describe here, but, with time, have been terraformed to earth-like planets. This is logic as humans will probably try to get their environment more hospitable. This could explain the likeness between the two planetary systems, as Clonus mentioned... Anyway, thanks for the comments. Now I'll be able to think more about it, again... Quote Link to comment Share on other sites More sharing options...
Thia Halmades Posted December 14, 2007 Report Share Posted December 14, 2007 Re: Setting for a "realistic" campaign in space Rule One: Divorce your mind from the source material. You aren't writing BSG, so don't try and "unwrite it," or you'll just go in these weird mental circles second guessing every bleeding design decision from here to kingdom come. Trust me on this. After (gad, a year?) working on HERO: Combat Evolved, I know a fair bit about recreating something, and about designing things that are inspired but have to breathe their own life. Penn's right, if you make them 'identical' it looks artificial, and you don't want that. Change it up. The planets are SFX anyway. How realistic do you want this? It's well established that snub fighters are pretty much a waste of time & money, but forgiving that for a moment, you have a solid chance of creating a nifty jet-jocky campaign setting. You'll want to flesh out the bulk of your military, and if you want a 'videogame/modern' feel, lots of different craft. The Viper II class is interesting because in that time period, I assume the idea is that it can be configured into whatever they need, whether as a strike ship, interceptor, dogfighter, or bomber. In most settings, that'll all get dropped for the excuse to design & name all kinds of cool, groovy planes. You can then have people specialize (ala Voltron) in one specific class, or (like some real pilots) be trained in multiple varieties. It's up to you, really, how you want to swing that. I've always preferred hard military/low realism, so I have LOTS of ships, LOTS of different guns, but with that gritty, chemical firearms feel that I groove on. Quote Link to comment Share on other sites More sharing options...
Foxiekins Posted December 15, 2007 Report Share Posted December 15, 2007 Re: Setting for a "realistic" campaign in space Potentially, a larger star could have 5 habitable worlds, if you stretch things... Innermost World, low in greenhouse gasses, is only habitable at the poles... Next World Out is closest to Earth... Third World high in greenhouse gasses, only habitable in the equatorial band... Fourth and Fifth Worlds orbit a gas giant... They would be too cold, except that a large gas giant will radiate heat... The innermost of the two would be a trifle warm, and the outermost a trifle cool... There would be other moons, but I believe you couldn't count on more than two having a decent temperature... Then, if you have a binary system, repeat... I would pick a respectable total number less than 10... Six or seven, maybe... Quote Link to comment Share on other sites More sharing options...
Kristopher Posted December 15, 2007 Report Share Posted December 15, 2007 Re: Setting for a "realistic" campaign in space I'm fairly certain that the gas giants in our solar system, at least, don't radiate enough extra heat to make any real difference in the habitability of their moons. Jupiter is the closest to the sun of the four, and radiates more energy than it receives from the sun, and all of its moons still have frozen surfaces. The source of heating that gives rise to Io's volcanism and Europa's probably liquid water is actual internal tidal stresses induced by gravity from Jupiter and the other large moons. Quote Link to comment Share on other sites More sharing options...
Doc Posted December 15, 2007 Author Report Share Posted December 15, 2007 Re: Setting for a "realistic" campaign in space Rule One: Divorce your mind from the source material. You aren't writing BSG' date=' so don't try and "unwrite it," or you'll just go in these weird mental circles second guessing every bleeding design decision from here to kingdom come. [/quote'] Thank you for the advice, but don't worry. I may be new to hero system, I still have a couple of years of GMing behind me... Potentially, a larger star could have 5 habitable worlds, if you stretch things... Innermost World, low in greenhouse gasses, is only habitable at the poles... Next World Out is closest to Earth... Third World high in greenhouse gasses, only habitable in the equatorial band... Fourth and Fifth Worlds orbit a gas giant... They would be too cold, except that a large gas giant will radiate heat... The innermost of the two would be a trifle warm, and the outermost a trifle cool... There would be other moons, but I believe you couldn't count on more than two having a decent temperature... Then, if you have a binary system, repeat... I would pick a respectable total number less than 10... Six or seven, maybe... I'm fairly certain that the gas giants in our solar system, at least, don't radiate enough extra heat to make any real difference in the habitability of their moons. Jupiter is the closest to the sun of the four, and radiates more energy than it receives from the sun, and all of its moons still have frozen surfaces. The source of heating that gives rise to Io's volcanism and Europa's probably liquid water is actual internal tidal stresses induced by gravity from Jupiter and the other large moons. Kristopher's right about the gas giants. Moreover, a larger star doesn't have a larger habitable zone; the zone is just farter away from it. Plus, two large stars would have to be far away one from another if the planetray system is to be stable without any catastrophic tidal waves. Even the stars themselves could act one on the other, the more massive one acreting matter from the other, creating a band of travelling gases inbetween. Quote Link to comment Share on other sites More sharing options...
Silverhawk Posted December 15, 2007 Report Share Posted December 15, 2007 Re: Setting for a "realistic" campaign in space At a distance of 100 AU, what would be the effect of the stars gravity on eachother? Is that close enough that their gravity would be trying to suck matter from eachother, and also maybe skewing the orbits of the planets? Gravitational effects would depend on the mass of the two stars. If they are of fairly equal mass their individual gravity would likely be balanced at 100 AU. But considering that for a G2 main sequence star the habitable zone is roughly around the 1 AU mark there should I think be little effect by the second star. Gravitational effects would also come into play if the orbit of the second star had an high eccentricity that brought it closer to the primary. But if the average separation is 100 AU that would be a very very long time. Quote Link to comment Share on other sites More sharing options...
Bygoneyrs Posted December 18, 2007 Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space I still like my first design of 2 worlds about each star, works the best! You could also state that they have never made the leap to discover star drive tech. Simply position your binary star system between galatic arms within the galaxy and there isn't another near by solar system to be able to reach. Thus this would explain why star driv tech was never seriously worked on, and why they would have focused on doing tera-forming projects on the various different world to make those four different world liveable to humantity. As to space ships, maybe you base the ships off of Traveller based smaller ships. Thus System Defense Boats, and small merchants and etc. Make the crews like 4-5 men with maybe a robot or two with a AI computer and etc. Penn Penn Quote Link to comment Share on other sites More sharing options...
Clonus Posted December 18, 2007 Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space I still like my first design of 2 worlds about each star, works the best! You could also state that they have never made the leap to discover star drive tech. Not having developed interstellar drive is actually the default condition. There's very little reason to expect practical interstellar travel without a superscience handwave. Quote Link to comment Share on other sites More sharing options...
Basil Posted December 18, 2007 Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space I spent 20 minutes crafting a great reply, and the computer hiccuped and it went bye-bye, so excuse my bluntness. 100 AU is a large distance; 10-30 is average, 1-10 is "near". Divide the closest approach of the two stars by the greatest distance between the planet and "its" star. Call the the distance ratio. A distance ratio of 3.5 - 4 is sufficient for long time stability, in a system where the stars' orbit has an eccentricity of 0.0. As the eccentricity goes up, so does the distance ratio. The average eccentricity of binary stars is ~0.5; this means a distance ratio of ~20 is needed. BTW, the distance ratio requirement is independent of the masses of the stars, unless the masses are extremely disparate, and even then it is not much affected. A gas giant will be found within the habitable zone only if it is "slowed down" by extensive "clutter" in the system, and such clutter (asteroids, gas, dust, etc.) will only be at high enough levels if there is no other sizable body in the system. IOW, if there's a gas giant in the habitable zone, there is no terrestrial planet in the system; one or the other but not both. BTW, grinding through the clutter will knock loose any large satellites that may have formed. Note that the habitable zone is much narrower than was thought even 10 years ago. For A star like Sol, it is about 0.2 - 0.25 AU "deep". Due to orbital mechanics, you cannot have two sizable bodies with orbits that close. Given 100 AU as the semi-major axis (average distance) and an eccentricity of 0.5 (average amount), no body will stay in a stable orbit more than ~2.5 AU from either star. It would be possible, if highly unlikely for each star to have a planet that could support a "shirt-sleeve" environment, but no more than one each. Thus, your dozen planets shrinks to TWO[/b. This, folks, is why I consider TV "scienterrifiction" not worth the effort to vomit on its writers. BTW, this should hardly impede your game, if you put most of the population in space habitats; there's little to limit the number of such habitats, and they can be at any distance from the star(s), except for orbits too close to be shielded without excessive effort. Just remember, the most useful orbits are those well out from the star(s)' gravity well --- out in the Oort cloud, where 95%+ of the system's volatiles will be found. Quote Link to comment Share on other sites More sharing options...
Doc Posted December 18, 2007 Author Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space I still like my first design of 2 worlds about each star, works the best! You could also state that they have never made the leap to discover star drive tech. Simply position your binary star system between galatic arms within the galaxy and there isn't another near by solar system to be able to reach. Thus this would explain why star driv tech was never seriously worked on, and why they would have focused on doing tera-forming projects on the various different world to make those four different world liveable to humantity. As to space ships, maybe you base the ships off of Traveller based smaller ships. Thus System Defense Boats, and small merchants and etc. Make the crews like 4-5 men with maybe a robot or two with a AI computer and etc. Penn Penn Not having developed interstellar drive is actually the default condition. There's very little reason to expect practical interstellar travel without a superscience handwave. Well, in some way, interstellar travels already "exist". http://en.wikipedia.org/wiki/Project_Orion_%28nuclear_propulsion%29 http://en.wikipedia.org/wiki/Project_Daedalus http://en.wikipedia.org/wiki/Project_Longshot This just takes decades to accomplish. The way I thought it, this system would have been colonized by humans from Earth a long time ago and no contact would have been maintained with it (because it takes so many years to travel). Then, planets would have been terraformed over the years to make them habitable without special equipment or infrastructure. But anyway, it seems Basil just blew up everything away... By the way, could you explain to me why a gas giant could only be in the habitable zone only if there is something to slow it up? Isn't it the contrary (the faster rotation, the nearer to the star)? And why does it takes dusts and debris to slow it down? Can't it have a slow revolution speed by itself? Anyway, thanks, everybody. Have fun! Quote Link to comment Share on other sites More sharing options...
Basil Posted December 18, 2007 Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space By the way, could you explain to me why a gas giant could only be in the habitable zone only if there is something to slow it up? Isn't it the contrary (the faster rotation, the nearer to the star)? And why does it takes dusts and debris to slow it down? Can't it have a slow revolution speed by itself? Anyway, thanks, everybody. Have fun! Um, I think you're confusing revolution (going around the star) with rotation (turning around its own axis). Also, perhaps, confusing the planet's period (number of seconds to go all the way around the star) with its velocity of revolution (meters per second). The farther a planet is from a star, the faster (m/s) it goes; the longer orbit is why its period (time of revolution) increases. Thus, as a gas giant in a "dusty" stellar system runs into stuff, it is slowed down. As it goes slower it can no longer resist the star's gravity through "sideways" velocity, and is pulled inwards. Closer in, its velocity is enough to keep from being pulled all the way into the star, and since the inner system is likely to be less "dusty", there comes a point where the gas giant is no longer being slowed enough to matter. This drag effect will likely knock loose any sizable satellites, as well. BTW, a gas giant in the inner system is usually referred to as a "hot Jupiter." A gas giant cannot form close enough to a star to be a hot Jupiter because during the early stages of star formation there's a period where the star is expelling a *lot* of plasma and so forth; during this period any hydrogen and helium near the star is blown away. This would rip the prospective hot Jupiter's H and He away, leaving a rocky body like the Earth (actually, it's more complicated than that, but that explanation will do). So, a gas giant can't form in the habitable zone and it can only wander into the habitable zone if the rest of the system is full of dust, gas, etc. Which won't happen if there's a rocky body in the inner system, because *that* body would pick up most or all of the dust, gas, etc. before it can do much to the gas giant's orbit. BTW, a hot Jupiter will not (quickly) be blown away by the greater radiation nearer the star because gas giants have a very high albedo. Thus, the hot Jupiter is reflecting most of the incoming electromagnetic radiation, and can keep cool --- well, cool enough to hang onto its H and He for a goodly while. So there you have it; either a rocky body in the habitable zone, or a hot Jupiter (probably with no large satellite), but not both. Quote Link to comment Share on other sites More sharing options...
Brother Jim Posted December 18, 2007 Report Share Posted December 18, 2007 Re: Setting for a "realistic" campaign in space Of course the system looks artificial !!! It was made by someone and the humans found it. Quote Link to comment Share on other sites More sharing options...
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