Starship Orbits in Trek

[Timo]

Stumbled on another orbit situation from The Mark of Gideon: "Captain's log, stardate 5423.4. We are orbiting the planet Gideon. [..] We were in synchronous orbit over the capital city of Gideon.". More proof of synchronous orbits over planet positions.

But not of freefall synchronous orbits. A figure-eight or a simple point hover above the capital could be what Kirk is describing here, and we get no deorbit threat.

Enterprise uses low orbits for planet surface scanning (exploration). It also uses synchronous orbits for dwelling over the same spot on the planet (for transporting and possibly communications). I love simple facts.

And the Mirror Enterprise uses low orbits for bombardment: obviously, a Terran ship would hide behind the horizon till the moment comes to rain death on the victim!

Well, now I'm deeply curious about how Spock reckoned that so precisely. [..] yet another example of the Vulcan people's love for false precision.

Also known as Vulcan humor. And this would be a perfect time for it: an obvious alien is making inane questions under potentially malicious pretenses, so of course Spock's sarcastic answer should match the absurdity of the question.

The one deorbit scenario that really annoys me, even allowing for drama and plot convenience, is in "Into Darkness". The Enterprise in near orbit of the Moon next to the Vengeance, and when her main power starts to fail, is suddenly in imminent peril from burning up in Earths' atmosphere!

The feeble excuse here is that the heroes wanted to get to Earth. Perhaps we missed the bit where Kirk commanded "Best speed to SF HQ, Sulu!" and Scotty went "Noooo, me bairns! They dinna work!" and Sulu said "Sure they do. Did you think all your underlings are utterly incompetent at making basic repairs?"... But then Khan gets a few shots in, and the ship again loses propulsion, now while en route to Earth along an impulse path that can certainly cover the distance in seconds.

The visuals still show the two ships close to the Moon where said gravity would not be an issue. But <insert classic argument about interior and exterior scenes perhaps not being in full sync>.

At that point in the movie, I've already been defeated by the fact that the Enterprise is forced out of warp closer to Earth than they probably should've decelerated on their own, and yet it's still treated as if they've been prevented from reaching their destination.

Closer? I think Sulu was trying to drop out of warp on the lawn of SF HQ.

Remember that Sulu in the previous movie parked within the atmosphere of Titan, after a mad interstellar dash at highest possible warp, and without any sissy final deceleration until he slammed the brakes. So he's quite likely to go "Can do, Sir!" when Kirk suggests that they bypass the arrival formalities at Sol, due to said formalities being solidly in the hands of Admiral Marcus.

Marcus tries to stop them from achieving their goal. He fails. And no wonder, since he

a) is flying and firing unfamiliar and untested hardware,
b) probably still wants Khan back alive, and
c) has no reason to worry anyway, since he holds the upper cards in armaments, jamming, cover story and clout.

On the other hand, perhaps he succeeds and gets exactly what he wanted. After all, he

d) has failed in the task of making the Klingons fire on the Enterprise, so now concentrates on making Kirk look like a terrorist - so he needs an audience, at just the right distance.

It is of little issue that what he wanted is close to what Sulu wanted...

Timo Saloniemi

 

[BK613]

Well, now I'm deeply curious about how Spock reckoned that so precisely. He must be using Mean Sea Level (or Mean Lava Level) of Excalbia, since anything else would introduce more than a tenth-of-an-inch variation in the orbit, but is he measuring to the bottom-most point of the ship, or its centerpoint? Of course, if the orbit wasn't perfectly circular, the ship would've also gained or lost altitude while Spock was talking, making yet another example of the Vulcan people's love for false precision.

Perhaps he is just reading off the display of the 23rd century version of a radar or laser altimeter. Which are pulse-and-return type devices that initially measure the actual distance between the emitter/detector and the ground.

 

[Timo]

...Aka false precision or meaningless/misunderstood data. But how often is Spock really guilty of that? When reading off distances to hostile forcefields or threat signatures in landing party duty, he would be within his rights to go for centimeters lest Kirk fry his fingers or bump his nose. When counting down to destruction, he'd better be on the mark exactly, even when it's ten minutes to T still. And he's entitled to being particular about his age (the way Sarek is).

Of course, in this specific case, Spock has no display available! (But perhaps he uses his Vulcan hearing for discerning a verbal output interface nobody else can hear?)

Timo Saloniemi

 

[uniderth]

Looking at circular orbits, for each distance away from the planet's surface you have a specific orbital speed. A synchronous orbit is at a distance where the speed of orbit matches the rotation of the planet. So this distance will change based on the rotational period of a given plant.

In an elliptical orbit your speed is greatest at periapsis (closest point) and is slowest at apoapsis (slowest point). So you can actually move at a slower of faster speed that a circular orbit would allow by having an elliptical orbit. This would allow you to have momentary synchronicity by having a slower or faster speed for a given distance with a circular orbit.

So you could in theory have a synchronous orbit farther away the the circular one, but you would need constant thrust towards the planet surface. Basically, would would be using brute force to rotate your elliptical orbit. You could also maintain a synchronous orbit at a closer distance than normal. You would need just need to be moving slower than the circular orbital speed using brute force to prevent you from falling towards the planet. If your orbit is low enough your periapsis would be within the planets atmosphere, or even within the planet itself.

So as has been mentioned by others the Enterprise could be hovering over one spot in a low synchronous orbit; which would require constantly using the impulse engines to prevent it from falling down to the planet. I think this makes sense with what we see on screen.

 

[BK613]

need to be ultra precise in your measurements if you want to put transportees down on the soles of their boots.

 

[Timo]

True enough. It's just that you need to be precise timewise, too, with the distance changing by the millisecond as well as by the millimeter. So Spock's quip to "Lincoln" can't be taken seriously in that sense, either.

Timo Saloniemi