Problem of math

You can get some wierd stable orbits.
You could get a ring topology where a series of many bodies circularly orbiting a common center (with no object at that center). To get this configuration into something stable, you need to alternate between high and low mass objects.


but a system of 3 equal mass bodies is not generally stable.
The standard legrange points require that the mass of C is insignificant to B is insignificant to A.

So far I am understanding most of the science that is going on, so I think that is a good thing.

I wanted to keep some info fresh in the thread-
- The diameter of the system is 2 LY from the outer most point to outer most point. Our own system is a little over 3 LY across.

- I think I can keep most of the campaign within the range of .5 (that’s a half, the period looks to be barely there on my screen) to 40 AUs- which is a far amount of space. Anything out beyond about 10 AUs I think will be in a protected dome or space station, because of the improbability of a survival able atmosphere out any further then that, but that area still works for me.

- Atmosphere travel can be restricted by drive type, snap of fingers, and what ever else magic the GM uses, so that helps.

- Interstellar speeds not fast enough to get any where so that isn’t something I should have to worry about to much.

- I still have some campaign ideas that would require the PCs to travel some 60,000 AUs- but I have faith in the people of EN to help me figure that out.

- I am still thinking about speed of the ship in space, and wondering about how fast is to fast and how fast is to slow (1 AU/day is to fast for the inner system stuff while 1 AU makes the outer system (60k AUs out) seem implausible). Shuld I just wave the hand on that too and say- “you are there,” or should I come up with a reason?

Thanks for your thoughts and science and stuff, its making this thing a little easier.

Harmon said:

So far I am understanding most of the science that is going on, so I think that is a good thing.

I wanted to keep some info fresh in the thread-
- The diameter of the system is 2 LY from the outer most point to outer most point. Our own system is a little over 3 LY across.

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The solar wind in our solar system only extends out to 130 AU.

The sun's gravity is more noticable than intersteller forces until almost halfway to the nearest star system - about 2 light years radius (but this isn't really a good measurement).


Our termination shock occurs around 95 AUs out, and could be used as an explanation why you can't escape the star system. A brighter sun means a farther heliopause, so you can set the distance to pretty much any number you're comfortable with.

My suggestion is to go with a jump gate system and relatively low speed travel. Make it so that a jump gate must be at both the destination and source location. Also make it so that when jump gates get to close to each other or a gravity well, they cause interferance with its operation.

This way you might have to travel a several hours to a few days from any planet to reach the nearest jump gate. And you might have to take several jumpgates to reach a distant location, each with several days of travel time between them.

This would effectively keep the players "in system", allow for travel times from many hours, to days or even weeks if you can't find an efficient path between the directional jump gates.

For those portions of the campaign that require the PCs to travel far (60K AUs), have someone (Corporation, government, etc.) provide them with a new prototype drive that will get them that distance much, much faster. Have it be built on technology that won't be readily usable by the populace in general for decades to come.

This gives you option side adventures as well. The drive could malfunction, and they could end up somewhere they shouldn't be. Or perhaps another corporation has found out about the drive and tries to steal it...lots of options.

And the best part is, you can always take the drive system back after the PCs are done with the portion of the campaign that requires them to travel so far across the system.

Harmon said:

- The diameter of the system is 2 LY from the outer most point to outer most point. Our own system is a little over 3 LY across.

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That depends a bit on what you are calling "our system". Alpha Centauri is a bit over 4 ly away - so you're saying nearly half way to the nearest star is still "our system" instead of "deep space".

- I still have some campaign ideas that would require the PCs to travel some 60,000 AUs- but I have faith in the people of EN to help me figure that out.

Click to expand...

Describe, please, why they would be "required" to do that specific distance? What's special about 60,000 AU? Why can't it be "far, compared to what you're used to, but not by threeorders of magnitude?"

- I am still thinking about speed of the ship in space, and wondering about how fast is to fast and how fast is to slow (1 AU/day is to fast for the inner system stuff while 1 AU makes the outer system (60k AUs out) seem implausible).

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Consider that Columbus' first journey was something a bit short of three months long, and significant trade between the Americans and Europe continued with similar travel times. Having the journey be that long may be inconvenient for the PCs, but it is not implausible in the sense of humans doing it in general. Humans have often taken multi-month endeavors, if there's a good reason to.

Umbran said:

That depends a bit on what you are calling "our system". Alpha Centauri is a bit over 4 ly away - so you're saying nearly half way to the nearest star is still "our system" instead of "deep space".

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From the center of our system to the outer reaches of the Oort is about 1.5 LY. I would presume that AC has about the same around it though I have no time to research it right now- sorry, typing one handed while rocking a baby.

As far as your assumption that I consider the Oort deep space- I consider it to be the far back reaches of my back yard, the area where I never, ever run a mower, the area where if I wake up early enough I can see deer. Is it my land? Not sure, never had it survayed, I suppose when I get out that way I will, but right now it ante no one elses. The area just beyond the trees out there, where- if you walk out there, you can see ol' Centauri's place, well that would be where his back yard starts, but the area where you can't see neither his house, nor mine, well that is what you call Deep Space. That is the best explination of how I think it works, because no one in all our 40 years plus of space travel has ever gotten out that far.

Umbran said:

Describe, please, why they would be "required" to do that specific distance? What's special about 60,000 AU? Why can't it be "far, compared to what you're used to, but not by threeorders of magnitude?"

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I require nothing of no one. I ask that you be kind, and respectful, but its not a requirement. I learned not so long ago never to require anything of anyone- friends, family, loved ones, complete strangers, all I can do is ask, and that is what I am doing- would you please help me with these? I have minimal understanding, and a few ideas, I know that 90% of the population is smarter then me and I believe in my heart that about 95% of EN Worlders are smarter then I, so it kind of tells you the level of respect I have for you all.

As far as why- there is a mega plot element out there, and I would rather not give it away before I use it.

Umbran said:

Consider that Columbus' first journey was something a bit short of three months long, and significant trade between the Americans and Europe continued with similar travel times. Having the journey be that long may be inconvenient for the PCs, but it is not implausible in the sense of humans doing it in general. Humans have often taken multi-month endeavors, if there's a good reason to.

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I agree.

Say you have two plants on opposite sides of the sun, one is at 1 AU and the other is at 3 AUs- that means that they are 4 AUs apart, if the ship can go through the sun, then yes, that would be true, so increase that to 5 AUs because they have to go around the sun and all that. Now what would be a good time for that to take? A week? A month? If its a month then 60,000 AUs is going to be a pain cause that would be like 12,000 months. A might beyond the time line that I want to work with.

However if the 5 AU trip only takes a day then we are talking only 10 days out to 50 AUs and that seems a might to fast for what I want to do.

I know that you are Mr Physics- which means you are smart, I know that I should hear you of all people out on this.

Thank you all for your time, your patients, and your brain power. I am only asking for your thought, which you have given in kindness- thank you.

Two drives - graviton and planetary

Make the ships use two modes of propulsion. The critical one is some sort of barely understood graviton drive - it's effectiveness is somehow directly proportional to how close it is to a gravity well, and the amount of gravitational tug in the space-time frabic isn't nearly as important (but might still have some influence) as how close you are to the "bottom" of the nearest well. Best use is when you are "near" a planet or star, but too close would mean either the engine would rip off its moorings or crush the people inside when the engine was flipped on/off. How close you can actually be to a celestial body for the changeover to be safe depends more on when the ship was made and by whom, as it relies more on the metallurgical constraints and/or internal inertial/gravitational field compensator technology at the time of construction then the engine itself.

That forces ships to use a more dependable (but slower) drive both when too close to planets/stars and when too far away (interstellar). Something lower tech like ion, chemical, maybe nuclear fusion.

Only thing I'm not sure on is whether the "effectiveness" of the drive mentioned above should be its accelleration or speed. I kind of like the techno-voodoo of affecting speed directly. This would ironically make the ship (and trip) faster on both ends of the journey rather than at the midpoint of a conventional trip of accelleration/turn around/deceleration. Inhabitants of your universe could easily find that hopping between planets that are only vageuly the same direction still results in a faster overall flight than heading straight for your end point.

Harmon said:

- I still have some campaign ideas that would require the PCs to travel some 60,000 AUs- but I have faith in the people of EN to help me figure that out.

- I am still thinking about speed of the ship in space, and wondering about how fast is to fast and how fast is to slow (1 AU/day is to fast for the inner system stuff while 1 AU makes the outer system (60k AUs out) seem implausible). Shuld I just wave the hand on that too and say- “you are there,” or should I come up with a reason?

Click to expand...

This is only a suggestion, but personally if I were going to do this, I'd make the trip part of the adventure, or even a little prologue/mini-adventure in and of itself. The details of it completely depend on how the campaign world and the overall trip is set up, of course. For instance, is it going to be just the PCs on their ship, or them and a bunch of other people on it? The former I might have their ship damaged or supplies ruined, and see how well they can problem solve. The latter opens up all sorts of possibilities for NPC interaction - one of them flips and starts killing people, or maybe there's a sinister reason - someone is trying to stop the PCs from even getting there. Either way I would play up the claustrophobia and the isolation of the ship that far out as opposed to the more settled worlds.

Rhun said:

For those portions of the campaign that require the PCs to travel far (60K AUs), have someone (Corporation, government, etc.) provide them with a new prototype drive that will get them that distance much, much faster. Have it be built on technology that won't be readily usable by the populace in general for decades to come.

Click to expand...

[PSEUDOSCIENCE=TECHNOBABBLE]
The Fusion Ramjet

The fusion ramjet is a tubular structure that uses intensely powerful electro-magnetic fields to sweep up the trace amounts of interplanetary and interstellar atoms, such as ionized hydrogen. The swept up particles are funneled into the ramjet's reactor via the E-M fields, where they are compressed and heated to the point of inducing a nuclear fusion reaction, which can then be focused out the exhaust nozzles using the same E-M fields (which can be reversed for deceleration purposes. The result is a powerful, high acceleration engine with a virtually unlimited fuel supply, which, while unable to obtain superluminal speeds, is eminently suitable for extended voyages.

Unfortunately, the ramjet requires constant forward motion and a certain minimal amount of reaction mass to sustain the fusion reaction. This causes three major drawbacks:

First, any spaceship using the ramjet much reach a certain minimum velocity before the fusion reaction can be initiated. This minimum velocity is directly proportional to the concentration of reaction fuel available. It has been noted that some pilots have been able to ignite their fusion ramjets from a near standstill while orbiting in the upper atmospheres of planets. This is highly dangerous, however, as an excessively high concentration of reastion mass can overload the E-M containment fields, causing the reaction to occur in an uncontrolled manner, using resulting in the destruction of the ship and anything within the immediate vicinity.

Second, any spaceship using a fusion ramjet has a severely limited turning radius. While the ionized fusion exhaust can be directed suing the E-M field in the exhaust nozzles -- even to 180 degrees for rapid deceleration -- forward motion is still required to collect the necessary fuel to propegate the fusion reaction. Adjusting the ship's axis more than a few degrees from the line of it's trajectory will very likely provide inadequate fuel collection. The engine will stall, and the fusion reaction will be extinguished.

Lastly, the density of interplanetary and interstellar gas is by no means consistant. Pockets of "high-density", "low-density", or even empty space may exist. Explorers traveling through uncharted space do so at their own risk.[/PSEUDOSCIENCE]