Will the planets actually move?

As for spinning planets and moving them, it would be simple. Those huge engines would just slow the spin, line up where its flying to, fly there, then slowly start spinning again. That would look pretty sweet too, giving a great sense of epicness as this planet begins its journey to a new location.

Or they could just place the rockets on the north/south pole and ignore all that nonsense.

Moving planets in the early game (I.E. moving through natural rotation) would be interesting. Imagine starting out on a planet adjacent to another planet; holding another commander. You and he go back and forth until his planet moves off, giving you a window to recover...

A while later, you and he have both gotten to the point where you can build expansion modules (I'm assuming that's what the commander-transports are called) so you can set up on new planets... you setup thruster installations on those expansions, and then it's just a matter of closing the distance.

Is anyone else visualizing late-game thruster equipped planets/moons/asteroids/etc. chasing each other through a solar system? Because to me that seems hilarious!

There are lots of different ways in which planets can move. For each one you have to ask what it would add to gameplay.

-Planets orbiting their suns: Not sure this is necessary. It may be fun, but more likely a needless headache. I mean, your enemy used to be 2 minutes away but now he's 20 minutes away - what's the point? Probably best if all planets exist at a fixed distance from each other and from the sun. It would be interesting as an option.
-Planets rotating around their own axis: Definitely. This gives you a dynamic day-night cycle and determines the power of solar cells. Thrusters should also be able to change a planet's rotation, and the global heat map should respond in real time (see terraforming thread).
-Moons orbiting their planets: Yes, I think so. This is more fun than planets orbiting stars since you always know how far away a moon is. Adds tension to lunar bombardment. They should also rotate around their own axis and be able to be tidelocked like planets.
-Planets moving towards or away from their star: Yes. And the game should offer a reasonable facsimile of the temperature and atmospheric effects you would expect. Again see the terraforming thread for a proposed mechanic.

There should definitely be simplified, but full, orbital mechanics in the game. Planets should move through their orbits, moons around their planets, etc.

I totally love the idea of prepping for a close enconter with two planets, unit cannons ready, interplanetary transports packed and ready for the launch window. A brief (or not so brief) exchange before the orbits takes everything out of range.

You could push asteroids into the orbital path of the other planet as a cheap bombardment too.

I am planning on some serious space marbles.

A few questions that plague me:
1. If the impact of the meteors is affected by velocity of impact will the trajectory and path determine how long the asteroid has been gaining velocity and therefor the damage that will be inflicted by it? And if so will I have full control of how many objects I slingshot around and the path I take to my impact sight? In the example game shown the asteroid slings around the sun which is a nice deep well to slingshot off of.
2. If the solar system is one big map full of objects is the galaxy also part of that map just further zoomed out? How will travel between solar systems look? Is it similar to travel between planets? I can't wait to see more game play. Super excited.

Bast

Both my knowledge of physics and imagination have been wiped out, but i'm playing with some thoughts.

Real planetary physics don't necesseraly imply boring gameplay.

It's obvious that celestial bodies in this game can't be the same scale as real planet. And this counts for all other distances as well!

This means that celestial bodies will be orbiting a lot closer, therefore have to orbit a lot faster to make up for the short distance. Otherwise they would crash into each other.

If you would try to get to another planet on the opposite side of the sun that's 20 minutes away, that's plainly foolish. You could just wait a couple of minutes until it's in reach to hop over.

This opens up great opportunities!

Imagine yourself waiting for alignment to hop over to another planet and hope you will succeed in establishing and keeping your new base alive when it's out of reach.

The same goes for the enemies. If you conquer a planet on an orbit beyond the enemy's orbit, then you can wait to attack until his outer planet aligns with yours and he can't reach you because his home planet is too far away! Mom won't help you now, kid!

This dynamic also means you can't really turtle on planetary scale. Your home planet isn't necessarily safer since it can always end up orbiting out of other's planets' reach.

If star systems or galaxies would slowly change (according to the same distance/time proportions as planetary systems), this would also be another dynamic to prevent a long game from bogging down. The clock is ticking slowly. One hour from here, you may find yourself close to a lot of enemy planets, so you better prepare!

Etc. etc. etc.

Let's use an example:
Earth's semi-major axis (so eh simply put orbit radius) is about 150M km. Let's divide that by 1000 so we get a less ridiculously large number. Then, instead of a whole year, our planet would only take, according to Kepler's third law:



= seconds.

This is only 17 minutes, but the sun is still 150k km away compared to earth's diameter of about 13k km, so rougly 10 earths away!

Mars has a semi-major axis of 228M km, so this amounts to:

= seconds = 31 minutes at a distance of 228k km.

The distance between Earth and Mars would then be about 78k km, so 6 earths in between.

This is enough within my major I feel obligated to respond. All bodies experience a gravitation pull towards one another and as the ratio of mass between two bodies approaches one effect is noticeable on both. For small bodies (like asteroids, spacecraft, and even moons to a degree) you can take an "ideal" assumption by assuming that the body has no effect on the planet gravitational-wise. By making that assumption and also assuming a point mass, calculating geosynchronous orbits is not terribly difficult.

So, I guess the only limit for a geosync orbit is that the satellite must orbit around the equator of the object (plus or minus a degree) and at the correct altitude.

Edit: Hope that explains, if you have any more questions just ask and Ill do my best to answer

Except then you'll have too little/much kinetic energy to maintain that orbit.

(I'm assuming that we're talking about unassisted orbits, so no extra rockets/thrust keeping you at that combination of speed+altitude).

We are. Settling into an orbit requires quite a few calculations (simpler than you would expect though). You just need to have the correct velocity and angle of approach to name a few. So, if you do it correctly then you do not have an issue maintaining the orbit.

Satellites do it all the time (change orbits). The only reason why you hear and read about satellites having unstable orbits and needing to be boosted back into position is because the LEO (Lower Earth Orbits) satellites do experience friction from the air (although there is hardly any air, it is present). Geosync orbits are far enough out that they do not experience this issue. Now, I am not including the effects of solar wind which also pushes satellites around.

On a side note, there are five points in space between two large objects (ie, earth and sun) called Lagrangian points that you can send satellites to orbit around.



These points act as psudo-bodies that you can have satellites orbit around.

Lagrange Points != Geosynchronous orbits. Pretty darn sure my point still stands.


Don't be afraid to throw out an equation or two. Anything less than a 3rd order ODE is considered easy.

Lagrange Points do not equal Geosynchronous orbits; they are two completely different concepts. Geosynchronous orbits are an orbit around earth where the object stays over the same surface spot. A lagrange point is a location in space that due to the gravitic pull from two large celestial bodies will allow an object to orbit that point.

I have to get to class now, but Ill dig out my old equation sheets and throw a few up for you to look at later (or just scan it). None of the equations are ODE.

That's because someone already solved the ODE's for the simpler cases.

And while you can get interesting results if we start doing N-body problems (like Lagrange points, Interstellar transport networks), I'm curious to know how much we can get into a nice game UI.

Things that would need to be shown to the user are not just orbits, but what area of coverage you'd get both instantly and over time.

A question I'd like to answer is "When do I attack with my ground troops so I can support them with orbital strikes?"

Correct, I was gonna say that I was not going to show the proofs for all of them because that was about half of the course where I get these formulas for and I absolutely dont want to do them again.

For traveling between two bodies there are multiple types of transfers you can achieve. For the game I think you could simplify it into two types for simplicity sake. You have (im forgetting the term) a transfer that requires the least amount of energy, but takes the longest and the alternate is a fast transfer which requires tons of energy but gets you there much faster.

So, I think if you give a player the two options of transfer (less time= more energy or more time but less energy) that would be good. There is no reason (from the games standpoint) of offering the entire range of transfers because the number of time and energy requirements for each options is infinite.

I cannot speak for the dev team regarding the UI that would be needed to implement your idea (as awesome as it sounds).

The name is Hoffman transfer orbit. The alternative is a direct transfer (I'm not sure if there is a better term), it's what they consider for mars missions so the astronauts don't get cooked by the rads.

I'm of the opinion the devs should hide the option of efficient vs fast because of another issue with orbits. Getting them to sync up with multiple objects is a royal pain and would not something players would want to deal with, i.e. how many slings around the sun do I need to get from planet A to planet B and so on. The syncing problem reduces the infinite options down to a limited set (especially if you don't consider things like slingshots around planets and moons).

I'd vote for you tell it the orbit you want to go to, and if there is something there it'll sync up with with by automagically figuring out the velocities needed. Also would be nice if they told you that waiting X mins would lead to a shorter total trip time (like how mars and earth naturally sync every few years hence missions every two years). Also, the initial video released was very much how I'd like it to be, you say go, and that's it.

It is actually called a Hohmann transfer orbit.

WRT Geostationary orbits (geosynchronous refers to the satellite in a geostationary orbit) Each celestial body has its own perfect altitude where this is possible using a circular orbit. Saying that you can adjust your altitude to get geosync orbit if you are going too fast/slow is not correct as the altitude of a stable circular orbit is determined by your orbital speed.

The altitude for a geostationary orbit around Earth is 35,786 kilometres

That's... exactly what the guy you're quoting said.

Maybe it is the Hohmann transfer orbit? The alternative is actually called a fast transfer far as I know.

Didnt realize the exclamation point stood for not equals. Never saw or did it that way. I just threw Lagrangian points up because I thought they were interesting for anyone to look up.

You are correct and I have removed the offending statement. Now I have to wonder why the hell I wrote it in the first place .

Hmm I just realized my convoluted thoughts boil down to a minor concern:

Since orbital period, given the gravitational parameter of the star, depends only on the distance to that star, I wouldn't want to see an outer planet revolve faster than an inner one.

But in the end I doubt that would even matter. It's way simpler to make planets just orbit at an arbitrary speed that's just plain fun.

And I want to point out that orbiting planets would open up a lot of awesome gameplay possibilities without adding unnessecary complexities! <3