# Implying science in fiction



## wulfAlpha (Nov 30, 2017)

Ok I may have bitten off more then I can chew. I'm working on a Space Opera/ SciFi story involving... Well Mechs for lack of a better term. I'm trying to write an action scene that takes place in space but I don't really understand how orbital mechanics work. Any suggestions or ideas on how I can paint an accurate picture? Anyone know any orbital mechanics simulators? Or am I overthinking it? Any suggestions would be great.


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## moderan (Nov 30, 2017)

Here. And here.


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## wulfAlpha (Dec 1, 2017)

Thanks! This is what I was looking for.


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## Terry D (Dec 1, 2017)

moderan said:


> Here. And here.



Great. Now something else to waste my time. :coffeescreen:


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## Ralph Rotten (Dec 1, 2017)

Orbital mechanics in a nutshell.
To achieve a stable orbit you need to find the right speed.  Too fast and you spiral outwards.  Too slow and you spiral inwards.
Essentially, an orbit is when you balance inertial force against gravitational pull.  Orbital velocity depends on altitude.

If you really wanna play with orbital flight, get the Xplane simulator.  You can do AMAZING things with that software including space flight.  I have flown halfway to the moon before the numbers got too big and crashed my PCs one at a time.  
Here is some video of me flying the NASP into orbit around Mars. (Martian orbital speeds are about a 3rd of Earth's)
https://www.youtube.com/watch?v=gFIvA4Serz8

Here is the Space Shuttle taking off from Mars.  I almost go orbital in this one.
https://www.youtube.com/watch?v=GZnTT6q40Vw


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## velo (Jan 19, 2018)

*Not a rocket scientist, but this is my understanding*

An object in orbit is free-falling towards the thing it is orbiting.  When you are orbiting you're actually going past the planet so fast you fall around the planet.  

Look at the picture I attached.  I whipped it up as a quick example.  It's a matter of the average of two velocities- perpendicular and tangential to the surface of the planet.  The perpendicular velocity is a constant at any given distance from the centre of the planet and is caused by gravity.  The ship will enter orbit if its tangental velocity averages out with the perpendicular one like the dashed arrow labeled 'stable orbit.'  If you slow the ship's tangential velocity you get "decaying orbit" (or lower orbit) and by speeding up you get "escaping orbit."  

In terms of writing, as an example, if you want to go down to the planets surface you would not necessarily fire engines away from the planet (perpendicular to the surface).  You would fire your engines ahead of you, reducing the tangential velocity.  This will lower the orbit and eventually cause you to hit the atmosphere.  It doesn't have to be directly ahead but you have to slow the ship relative the surface of the planet so that the direction of fall no longer aims past the planet's surface.   To escape you would fire behind you, also tangentially to the surface.  

Larry Niven's _The Integral Trees_ is a fun read and takes place in a gas torus orbiting a star.  Not sure of the feasibility of that part but he gets a LOT about orbital mechanics (how the characters move in a zero-g orbital environment)  right.


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## hardlyboiledauthor (Feb 27, 2018)

Unless you are actually building a contraption of some sort, it might help to think simply of how things would look. Think of it how Einstein did: [h=2]From the Great Courses Daily: "In 1907, physicist Albert Einstein devised what we now call the “elevator” thought experiment, in which he dreamed up the idea of having an entire physics laboratory inside a falling elevator. The result of Einstein’s experimental elevator experiment was nothing less than the principles underlying the General Theory of Relativity.[/h]
I really love to picture it that way, Einstein has the physicists conduct all kinds of experiments in his fictional elevator : ) 

Best of luck,
Shaun


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## Bodes (May 21, 2018)

This might be unconventional advice, but I just read tow sci-fi novels and to be honest, they both really skimmed over the science part of the story. I think that theres a careful balance that needs to be stuck between acknowledging the scientific ideas that make your story plausible/possible but also not drawing too much attention to them. For example, I'd be hesitant to really draw attention to the science in my writing because I'm not confident enough to explain it thoroughly. Something explained incorrectly almost always draws more attention than something that was skimmed over.


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## moderan (May 21, 2018)

> sci-fi


is a pejorative, commonly referring to the kind of stuff you see on the SyFy channel, where accurate science is optional and even character is malleable depending on the immediate needs of plot. Otherwise, even the lowliest sf writer keeps up on current technological developments and works them into the stories.


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## Terry D (May 21, 2018)

moderan said:


> is a pejorative, commonly referring to the kind of stuff you see on the SyFy channel, where accurate science is optional and even character is malleable depending on the immediate needs of plot. Otherwise, even the lowliest sf writer keeps up on current technological developments and works them into the stories.



You mean, not like The Last Jedi, where bombs 'drop' in zero G, and people are able to function without space suits after their ships are ripped open? I can suspend a lot of disbelief in science fantasy, but that stuff had me yelling at the screen (I watched it at home, so I only annoyed my wife, not a theater audience).


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## moderan (May 21, 2018)

Never saw it. Prolly never will. But yeah, like when the oxygen rushes in in Total Recall. Like the sharktopus. Like that. Like looking through the wrong end of the telescope bad.


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## Rhymetravilla (May 28, 2018)

Keep in mind any sizeable objects in space and be aware of their pull of gravity if they are large.


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