Raghesh SyncStation

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Raghesh SyncStation

Postby dorward » Sun Aug 15, 2004 6:17 pm

Page 130 of the Centauri book shows a location marked Raghesh SyncStation. It 100% clear as to what this is. My best guess is that it is the orbital platform mentioned in the text - in a geosynchronous orbit. Is this right?

Also - is Raghesh a misspelling of Ragesh? The text matches up with what we know about the planet from screen and the core book, but it seems to have aquired an H from somewhere.
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Postby lastbesthope » Sun Aug 15, 2004 7:51 pm

Speaking purely from the standpoint of orbital mechanics any station in geostationary orbit must be directly above the equator of the planet. In this case the eguator being defined in relation to the axis of rotation, not as defined by any map system or using the magnetic poles as a reference. As such, unless the map is drawn funny I can not see the station being in orbit over the point marked on the map.

Perhaps it is the ground station in contact with the satellite, that could be located anywhere within LOS of the station in orbit.

As for the extra 'H' I don't know where that has come from but you're right, it wasn't there originally in the on screen display at the start of "Midnight in the Firing Line" (Aren't DVDs wonderful!)

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Postby Eryx » Sun Aug 15, 2004 10:32 pm

lastbesthope wrote: Speaking purely from the standpoint of orbital mechanics any station in geostationary orbit must be directly above the equator of the planet.

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Interesting. Why is that?
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Postby Dag'Nabbit » Mon Aug 16, 2004 8:11 am

It has to do with the physics of orbiting a spinning spheroid/semi-spheroid. Gravity pulls any orbiting object towards the center of its mass. If you put an object in orbit outside the equatorial belt, it will not remain there. Gravity will pull the object 'down' towards the Earth's center. <This is a lot easier to explain with a drawing>

If you put an object in orbit outside a geostationary orbit, and without enough velocity to counteract the Earth's gravity, then it's orbit will decay and it will re-enter the atmosphere. If you do provide enough velocity to resist the Earth's gravity, then you will have given the orbiter a vector roughly perpindicular to the Earths gravity resulting in a stabilized orbit. If too much V is imparted on the satellite then it will eventually leave the Earth's orbit for open space.

In order to station a satellite in a geosynchronis orbit then you must fix it's position in orbit at a specific point in space that is fixed, relative to a point on the equator, so that it's velocity in it's orbital path prevents gravity from pulling it down. The math is not extremely complex, but very precise.

That explanation may have been a little much, but if you have questions let me know. If I messed up somewhere in there I'm pretty sure I won't have to remind any one to tell me. :wink:
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Postby Eryx » Mon Aug 16, 2004 12:45 pm

Dag'Nabbit wrote:
It has to do with the physics of orbiting a spinning spheroid/semi-spheroid. Gravity pulls any orbiting object towards the center of its mass. If you put an object in orbit outside the equatorial belt, it will not remain there. Gravity will pull the object 'down' towards the Earth's center. <This is a lot easier to explain with a drawing>
I'm no physicist or anything so this is the bit I'm having a hard time with. Surly wherever you place the satellite, its going to be pulled down by the gravity so I still don't understand why it HAS to be equatorial.

Thanx for the info.
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Postby mthomason » Mon Aug 16, 2004 12:51 pm

http://www.wordiq.com/definition/Geosyn ... _satellite

Has a nice explanation of the differences between geosynchronous and geostationary, as well as some of the scientific reasoning. Oh, and don't forget to click on the links to the two orbit types (well, one type and one subtype, to be more accurate) :)
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Postby dorward » Mon Aug 16, 2004 12:56 pm

Eryx wrote: I'm no physicist or anything so this is the bit I'm having a hard time with. Surly wherever you place the satellite, its going to be pulled down by the gravity so I still don't understand why it HAS to be equatorial.
OK, my astrophysics is a bit rusty, but as I recall:

* Gravity accelerates you towards the centre of the planet.
* When you orbit you are already moving in a different direction.
* So although you move closer to the centre of the planet, you are also moving away from the planet at a different angle.
* It works out that you stay the same distance away from the planet.
* As a result you have to orbit around the widest point of the planet, otherwise you are pulled off to the side.
* In a GeoSync orbit you are falling around the planet at the same speed that it rotates, so you are always above the same point on the surface.
* You can only achive this if you are above the equator as that is the only area on the surface that rotates along the widest point.
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Postby dorward » Mon Aug 16, 2004 12:58 pm

What? Using third party references? Isn't that cheating?
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Postby mthomason » Mon Aug 16, 2004 1:01 pm

dorward wrote:
What? Using third party references? Isn't that cheating?
Yes. :)

*rolls a d20, comes up with a 1, slips it up his sleeve*

Direct hit!
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Postby dorward » Mon Aug 16, 2004 1:03 pm

mthomason wrote:*rolls a d20, comes up with a 1, slips it up his sleeve*

Direct hit!
I've just rolled some dice behind my GM's screen. Now I have an evil grin on my face.
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Postby mthomason » Mon Aug 16, 2004 1:09 pm

dorward wrote:
mthomason wrote:*rolls a d20, comes up with a 1, slips it up his sleeve*

Direct hit!
I've just rolled some dice behind my GM's screen. Now I have an evil grin on my face.
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Postby Eryx » Mon Aug 16, 2004 2:16 pm

dorward wrote: * As a result you have to orbit around the widest point of the planet, otherwise you are pulled off to the side.
Ah, that makes sense now. Thankyou.
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Postby PottsBr » Mon Aug 16, 2004 7:35 pm

Orbiting a planet is like learning to fly in Hitchhiker's Guide to the Galaxy. You fall, but miss the ground. During the orbit, you are being accelerated towards the center of mass of the object you are orbiting. If you were a stationary object, SPLAT!! However, if you have enough forward velocity, you will miss the planet and go around one more time.

So long as you are well outside the atmosphere, this will continue almost indefinitely. The atmosphere will impose drag, which will slow you down, so you won't miss on that next pass, SPLAT!!

If your orbit happens to be circular, and you are at the right speed and altitude, you will be moving in concert with the rotation of the planet, like all those nifty Dish Network/Direct TV/GPS satelites.

One thing that has often bothered me is shows where ship lose power and start falling from orbit. What sort of orbit were they in? Were they deliberately operating slower than their altitude required and using thrust to counter gravity? Were they actually orbiting so low as to brush the atmosphere and require thrust to keep up speed? The shuttle (when it's flying) stays up for days without any power. The ISS goes months at a time with just the periodic boost. Somebody needs to teach these navigators how to calculate an orbit.
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Postby lastbesthope » Mon Aug 16, 2004 10:46 pm

PottsBr wrote:One thing that has often bothered me is shows where ship lose power and start falling from orbit. What sort of orbit were they in? Were they deliberately operating slower than their altitude required and using thrust to counter gravity? Were they actually orbiting so low as to brush the atmosphere and require thrust to keep up speed? The shuttle (when it's flying) stays up for days without any power. The ISS goes months at a time with just the periodic boost. Somebody needs to teach these navigators how to calculate an orbit.
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KISS analysis:

All orbits are elliptical. The plane of the ellipse must contain the centre of mass of the body being orbited. So to be geostationary the orbit must be over the equator at all times with an orbital period of 1 day and be circular (ellipse of eccentricity e=0).

Of course geostationary sats are rubbish for comms at high latitudes, so the soviets came up with Molniya orbits. You can find info by googling for Molniya orbit. It really is quite clever if you look at the maths. the US intelligence agencies ended up using them as well for satellites to spy on the Soviets. :D

If you think that's fun, try googling for Lagrange points and the Jacobi integral. I swear I still don't understand that to this day although I derived it in 2 exams, I only believe in L1, the other 4 take some believing.

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