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Abber_dun

Science of Space

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Just wanted to rant a little:

For those that are interested in a very good resource for hard Science Fiction try the atomic rocket website

http://www.projectrho.com/public_html/rocket/

Going back and reading a lot of RPG books I have noticed that a lot of people get some simple science wrong with respect to space, for example shadowrun, cthulutech, and Trinity/Aberrant think for some reason that space is cold.

In order to help people understand this or perhaps facilitate authors to google and double check some basics I'll go over some basics:

First Space is not cold or hot, it is a vacuum (very little matter to be found) and as such out of the three modes of heat transfer (conduction, convection, radiation) two do not apply, as conduction and convection require matter to be in contact. From a visual standpoint it will be hard to tell the temperature of an object in space (temperature being a property of molecules), an object not generating heat will, given enough time, reach an equilibrium depending on how much radiation it gives off and how much it receives and given that radiation is the slowest form of heat transfer imply s that you do not freeze in space until you have died (and after you stop generating heat) and radiated most of your energy away, which depending on how close you are to a radiation source could be never. The intensity of radiation follows the equation I=P/(A*r^2) which shows the radius away from the radiation source is a square located in the denominator, from math we know that a growing number in the denominator makes the number smaller and smaller, since the radius is squared the Intensity of the radiation drops off very quickly as you move farther and farther from the source. Also because of the difficulty in releasing energy in a time depending way, heat rejection is a major design consideration for space ships and space stations, expect to see major radiators (large surface area to radiate heat as thermal radiation) to dump heat generated from the power plant and drive, these radiators by their very nature are susceptible to damage (large surface area and thin).  

Second you do not explode when subjected to vacuum pressures, see https://en.wikipedia.org/wiki/Space_exposure

Third, it is very unlikely your space ship will be accelerating at a rate that could hurt you, You would be very lucky to have a ship that can maintain 1g of acceleration for long periods of time. Your body is going to feel the acceleration not the velocity (unless you are unlucky enough to hit something). So that takes the travailing so fast in space that you can liquefy people off the table as the shear amount of fuel you would have to shove thru your drive to get past say 5g's. Interesting note maintaining a constant and comfortable 1g of acceleration for about a year can get you to near speed of light, just remember to decelerate for the same amount of time. On the same note maneuvering in space you will only feel your accelerations (no air to bank off of and the physics are quite different, don't ask me to work that out I'm not a physicist, my degree is in Chemical Engineering) so what this means is that when you maneuver and say your ship only pulls some small amount of g's in maneuvering you wont have your eyeballs pushed back into your head. this also changes the dynamic in that dog fights don't really happen, think about it someone is behind you shooting lasers or whatever, you can change your ships orientation 180 degrees damn near instantly and just fire back while still travailing in your original vector, there is no need or advantage to maneuvering behind someone unless they somehow don't know you are there, and don't forget that is unlikely to happen due to thermal sensors being passive and that at current tech we can detect a toaster oven at room temp in space on the range rated in astronomical units.

 

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On the 180 degree turn, that isn't exactly instantaneous. Or more you don't want to turn too fast. If your design doesn't have your control seat dead center on the center of mass, you're gonna feel the centrifugal force of the turn. And even WITH that sort of setup you'll still have issues with such G-forces acting on your body when you turn. Or maybe not. Not exactly sure on it.

I do know if the design has your control seat/cockpit outside the center of mass you will feel the acceleration, limiting how fast you can do turns. Dead-center you might have forces acting on your arms/legs depending on how you're seated.

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What you'd feel is momentum, of which centripetal force is a merely a type of (often called angular momentum). Any time you speed up or slow down (changing directions is basically speeding up in a different direction), you'd feel that change in momentum as a function of inertia.

And while it's technically true space itself is not cold, deep space (that is a region of space too distant from a source of heat like a star or planet to get much radiation) will 'feel' cold because we lose heat in it from radiation, and no energy is 'returning' to us from it. It's true that only radiation exists as a means of thermal transfer, but an object left to reach thermal equilibrium with vacuum will become quite cold. It will just take time.

It is also true that things in space that generate more heat than they can radiate can get very hot indeed. This is mostly a problem for things like spacecraft that have to maintain a relatively narrow 'band' of temperature so as not to kill astronauts, but have a great many heat sources on board...including the astronauts themselves. A spaceship generates a lot more heat than its surface area is adequate to radiate quickly, so they have to be engineered to dissipate the heat. This can be done through circulating coolants, or through vanes or similar structures that artificially enlarge the radiating surface of the vehicle.

And of course, in regions of space that have a lot of radiation passing through them from stars or other sources, space can seem hot...though it's not space itself that's hot, there's just a lot of energy passing through it.

But yeah, for the purposes of RPGs and simulations of rules that are simple enough not to need a background in physics, it's simple enough to simply treat hard vacuum as what it is: an incredibly hostile environment. The presence of radiation makes it 'hot,' the absence of it makes it 'cold,' though really any temperature effect pales in comparison to the evacuation of water from exposed tissues and the differential in pressure causing oxygen to leave your body (ideally you LET it leave through the apertures your body normally uses, as counterintuitive as it seems), followed of course by the complications of lacking oxygen. Yeah, your dessicated, asphyxiated corpse might eventually freeze as it reaches thermal equilibrium with the energy state of the vacuum around it...but you'd be looooooooong gone by then.

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Well the misconception is that books seem to think you flash freeze, and even in deep space that is simply not true human body is roughly a surface area of 2m, not near any radiation sources you still loose heat very slowly think how much heat a thermal blanket reflects back to you for a very very approximate guess as to what you are loosing. As for as the point about turning around, since there is no friction to resist you, you can turn in place as fast as your thrusts allow while still traveling on you original vector thus allowing you to aim regardless of your path which is just very cool I might add. Space is very interesting to think about and there are a lot of things to consider. The flash freeze in space repeated in books set off my rant.

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Ahh, I see, yeah. No flash freezing. You could be flash-burned if you were too close to something hot, but you can't LOSE heat faster than you can radiate it.

And yeah, turning is literally just accelerating 'that' way instead of 'that' way. The new Battlestar Galactica did it better than Star Wars, though even BSG took liberties with the concept.

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1 hour ago, Sailor OOC said:

That's what I'm getting at. The maneuvering thruster causing you to turn.

Yep we are in agreement. I think what I was trying to say was that 2g's of acceleration is very fast and can turn you around fairly quickly and as we know 2g's of force is something you will feel but not something that is going to hinder you in any way unless its maintained for a long period of time, but for maneuvering I would think 2g's would be very good and get the job done with the pilot only feeling small pulses of discomfort. Talking about BSG if i remember correctly they also did nukes in space as flash's of radiation which is correct. ON a side tangent nukes would suffer from the radius squared in the denominator problem as well and well effective would be less effective then in atmosphere (air would stay heated for a while causing further damage and shock-wave thru atmosphere is really good at doing horrible things to concrete), just as an interesting side note, nuke shaped charges would be a better design.

Also keeping it trinity themed I have concluded that any race using gamma radiation as a weapon are just being mean (not gamma ray lasers, just bursts of radiation), the amount of energy required to kill someone in a time span needed in a firefight is a tremendous amount of energy (40 greys kills you in a day which is not useful in a firefight so you would need a lot more energy) that could be spent powering a more effective weapon. Conclusion the Coalition are sadistic.

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Yeah, 2g in space wouldn't need a full g-suit for protection.

Although I'd see for more efficient ship-to-ship combat, using magnetic coil/rail weaponry which would be far more efficient in space.

Things like particle beam weapons would require a good amount of power, but have lesser recoil. Lasers are nifty but you need them "painting" the target for more than a moment just to start doing damage.

Nukes while effective close-up are pretty expensive in terms of upkeep and in manufacturing, if the amount of uranium and plutonium is as rare and scattered as it is on earth, it would be far more efficient to switch to mass driver weapons.

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Technically a beam of charged particles would be nearly impossible to use in space. Firing enough particles to do damage means they're tightly packed enough that their charges start to interact and poof...they deflect each other out of the beam and scatter all over the place. Neutral particles would work, but I don't even know how you'd confine and direct them into a beam on a scale and energy level enough to do damage. Some kind of sci-fantasy gravitational tech maybe.

Flinging projectiles can work, but over the distances that one would expect space combat to be at, it'd take a hell of a shot. Maybe some kind of self-directing projectile...a kind of minimissile that's fired via conventional means (electromagnetics or chemical or whatever), and doesn't provide it's own main thrust, but has an engine capable of course corrections as it closes on the target...

Directed energy like lasers is easier in some ways, harder in others. It solves the issue of travel time rather neatly, making the question of who wins the battle entirely one of who has a tougher hull and who has higher power lasers. Holding the lasers on target wouldn't be an issue unless there was some seriously high performance thrust at work. Keeping the laser beam tightly confined enough to do actual damage at long ranges might be.

I suspect the only near-term space combat solution for Earth would be self-propelled missiles. Railguns and lasers requires power generation that's technically possible, but probably not very practical to install on a spaceship with our current technology. Missiles on the other hand, we're very good at making. And the truth of space combat is that in most cases a spaceship is a one-hit mission-kill. One big hull rupture means the ship is so busy trying to desperately keep itself alive that it can no longer fight back or complete whatever its mission is.

That situation changes of course as you introduce progressively more speculative forms of technology, but at that point you're only limited by your imagination.

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My father retired from an areospace space division.  He helped design and build a majority of 'next generation' space exploration equipment.  Things like vehicles, capsules, suits and gear that humanity could use when we decided to explore the stars.  It's pretty shocking the things they made, but what's more shocking are the things the didn't make.  I've seen some pretty cool things made from currently existing technology that would surprise us, but the things he told me they were capable of making but didn't, is what really made me a sci-fi nerd.

Get a few beers in him and he'd talk up a storm and one of the coolest things he'd tell me about was the experimentation of various weapons in ZeroG as well as a vacuum, and you'd be surprised at how far the space weapons development was coming along.  As a GM I'm not concerned too much with the science behind things, as long the players are having a good time, but I support Abber's original point: as GMs and Players, it is a good idea to know how all this stuff works.  I'd like to add though: 'as long as you and your troupe care enough to use it all'.

Don't smother your players with science.  Chances are they don't care.

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53 minutes ago, Dave ST said:

Don't smother your players with science.  Chances are they don't care.

As a "Rocket Scientist" in real life, I wholeheartedly endorse this. Sure i think the GM should have at least a basic understanding of the science behind the stuff she has in her game, but for the players for the most part if the science isn't the plot point keep it behind the curtain and out of the way of the story.

 

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It does help to, at least in a Soft Sci-Fi setting to consider the fiddly details to be taken care of by some form of technology that's behind the scenes. Something that becomes important when the plot demands (as it broke down).

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Yeah. I'm gonna have to agree with Nina and Dave. I'm not here for lessons in Science. For all I care, they could claim the void is full of pudding and as long as it was a good game, I'd roll with it. Broad strokes is all that's needed.

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Sorry for the late reply, My problem isn't with a crazy sci Fi setting or with things like super powers and what not, My problem is the myths or misunderstandings that can be cleared up with a simple google search being spread around as truth, which is what bothered me a little, Trinity and aberrant repeated the Temperature in Space ranges from -273 C to really hot in many books and is just wrong with information being readily available its a little funny, much like the translation of an episode of DBZ in which freeza states that he/she/it could breath in space which we know is bull and ending up being comical. Its not a huge deal, I admit.

I would just like the people who write these things to google some of it, a minimal level of research if you will when you have a scientific setting. Other than that there is no problem having fun with plasma blasts and time travel. Some research can add that much more to the setting as reality is often very interesting (space is a fascinating subject). To beat a dead horse its like having someone that lived in chicago or researched chicago when writing a source book as a reference, it adds to the feel without being a classroom lesson and im pretty sure we have all read some books about areas that just got alot of the stuff wrong and it was a little disappointing.

Ill add one more thing, its like that silly movie where Aliens invade with drones and weird power armor and the story was about the military fighting back. But the reason was they wanted water or something and that was why they attacked, bad reason from the start water is plenty available in space and no invasion was needed, thus was one of the reasons that made the movie a little lackluster, among other things. There are a lot of well written though experiments on why a hypothetical alien race might attack us that are a lot more logical then water, all they had to do was pick one of those and the story would be a little better as there is less handwavium. Another example is the new star trek, dude didn't need the ancient grey goo weapon, his drone fleet was plenty enough to take out the space station and thus part of the movie fighting over some ancient wmd lost its meaning.

I feel like I just ranted a whole bunch and I'll leave it at that.

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The Jovian Chronicles game I am restarting here is a sci-fi game, but also fairly hard science... to a degree. Essentially they explain things like inertia, radiation, using reaction mass for fuel, practical oribial colony design (the ones around Earth are very different than those around Jupiter in game due to different concerns) the crazy distances and travel times between planets, how orbits affect the distances and so on.

One example is that the big star ships are build with their decks going front to back instead of top to bottom (more like a skyscraper than a cruiser ship). When the ship begins a trip it accelerates up to 1G to simulate gravity by the acceleration holding people to the floors (which run ventral to dorsal in the ships, not fore to aft) and then half way through the journey they kill the engines, do a 180 spin (since their inertia is still moving them) which make for a brief period of weightlessness and then they burn to start breaking, thereby simulating gravity again until they stop.

The explain the basics and explain how things are delt with (like magnetic screens/force fields to deal with radiation) but at the same also say, "Yeah, this is the science of this stuff, but it should never really be much of an issue or get in the way of the game and fun unless the GM wants to make a critical plot point for a story or something." which is what I like.

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