When the Enterprise enters standard orbit what is that orbit? Is it a low orbit going around a world sixteen times a day? Or is it "geosynchronous" orbit going around once a day? The problem is the range of the transporter. 22nd century was 6,200 miles. 23rd was 16,000 miles. 24th was 24,800 miles. A geosynchronous orbit is 22,236 miles above sea level. This means that before the Enterprise D the transporters couldn't reach the ground from a geosynchronous orbit. A low orbit has it own problems, at any given time the ship might not be in position to beam people up or down. At how an acute angle to the surface can you still beam? If the ship is just above the horizon a lock might not work. And would you always want to use the transporter at it's maximum possible range or would a lesser distance be safer? I've come to believe that in Kirk's time the Enterprise wasn't always orbiting the planet, but was instead hovering on it's impulse engines above a fixed point on the planet's surface. For example Assignment: Earth, the Enterprise was stationary two hundred miles directly above the New York City. At that altitude she would have been orbiting at five miles a second, but at a hover she is moving forward at only at a third of a mile per second, matching the city below her. Impulse engines that could propel the ship at hundreds of gees through space can easily provide one continuous gee to hover. In the episodes Naked Time and Court Martial when the Enterprise's engines are cut the ship doesn't continue to orbit for months and years, but instead begins to fall towards the planet's surface. Do you think the Enterprise is always orbiting the planet?
This is one of many examples of where Science Fiction, especially in visual media, have done a great disservice to the science of orbital mechanics. See http://www.braeunig.us/space/index.htm for a detailed explanation. Unless your ship can ignore gravity, it will always be orbiting.
If your spaceship is capable of warping spacetime for propulsion, then I would think that ignoring gravity (AKA, the curvature, or warping of spacetime) would be an implied ability. In fact, creating a localized area of flat spacetime within a gravity well (a "ledge," if you will) would be child's play, would it not, compared to hurling the vessel hundreds of times FTL?
It establishes a standard "plot" orbit. Insomuch as from a visual standpoint it appears to be in a low orbit. From a communications standpoint it appears to be in a geosynchronous orbit. And from transporter standpoint it seems to be stationary at about 200miles altitude.
I think in a majority of cases, TGirl's right about TOS and how they handled orbit (usually a powered orbit). They just kept the ship hovering over the beamdown area. However, the TOS Enterprise was able to beam back kirk and crew from 30,000 km away (Obsession) which is only 5,000 km shy of Earth geosync orbit altitude. It might be fudgible to think that beaming range could go a little farther...
Don't forget that a planet's geosynchronous and geostationary orbits depend on that planet's rotational period.
By constantly applying thrust to match escape velocity for a given altitude and adjusting for planetary rotation, they can maintain a parking orbit above a certain spot for as long as they like. The lower the orbit, the more fuel it takes to do that. NASA can't afford to do it, but for a starship, that's peanuts.
I'd argue that a starship would be as likely to maintain a "natural" orbit as a modern oil- or nuclear-powered naval vessel would be likely to tack into the wind. If, instead of being slave to Newton, you can hover over a planet in a pattern of your choosing (and any starship worth the name can), then you will do so. It would be pretty silly to revert to a Newtonian orbit even once when you are likely to be using "powered orbits" and complex tactical patterns 50% of the time anyway. I don't think Sulu would ever choose a natural orbit unless explicitly told to do so - perhaps so that the ship could masquerade as an asteroid or something. It just wouldn't occur to him, any more than it would occur to the helmsman of an aircraft carrier to use his ship as a sailing vessel, even when conditions allowed for this. Sulu's natural instinct would be to fight the (insignificantly feeble) forces of nature, not to go along with them. It would take a "special" pilot, perhaps somebody fanatically interested in esoteric "naturism" of some sort, to actually bother with freefall orbits unless there's a specific need. Timo Saloniemi
Your forgetting that a "natural orbit" has a safer failure mode. With the powered orbit, if the engines fail, you fall. In a natural orbit, if the engines fail, you continue to orbit. Using a powered orbit would be like parking your car on a hill by putting it in gear and revving the engine just enough to keep the car from rolling away. Better to turn your wheels to the curb and engage the parking brake. I would imagine (as that's all we can do) that powered orbits would only be used as needed. Natural orbits would be standard ops if not.
...However, we know that starships don't actually enjoy such a safe mode, not when it matters. Sabotaging of engines was enough to send the ship on a death spiral in "Court Martial", without dialogue implying that Finney would have used those engines to initiate the spiral before completing the sabotage. To the contrary, Kirk first says he himself commanded the engines shut down for the time being (due to manpower shortage created by the hunt for Finney - the engineers had to beam down), and Captain Krasnovsky then worries that the orbit will eventually decay - to which Kirk responds that there's still some time before that happens, but apparently not years or even weeks. It's after this that Finney sabotages the engines, the ones that supposedly take lots of crew to operate even if only one man to sabotage. So it seems that parking a ship around a starbase planet for what's supposed to be an indefinite time (pending the outcome of Kirk's trial) doesn't involve using a stable natural orbit... Then there are a couple of cases where gravitic anomalies or tractor beams are acting on the ship, but that's a different matter. It might be that every time the ship wasn't sabotaged or didn't lose power, she was on a safe natural orbit. But that's statistically and dramatically a bit funny. Timo Saloniemi
If you cut the engines, while the Enterprise is hovering at 200 miles, she would hit the ground in 4 minutes and 16 seconds. From maximum transporter range of 16,000 miles, she would hit the ground after a leisurely 38 minutes and 11 seconds. Both times assume no atmosphere, I'm afraid I can't quite figure that out. Twice the distance (in meters) divided by 9.81, the square root is your time in seconds. The Captain's Log in Naked Time said they had nineteen minutes left. But that was a while after Riley cut the engines. There might be occasions when they're mapping a world where the ship would be in orbit.
That sounds about right. Keep in mind that in "The Naked Time" that it was less than 20 minutes to hit the atmosphere, so they might have been a little higher up or moving much faster than a simple hover...
^ There's also varying gravity to consider. Psi-2000 might have an acceleration of around 4m/s, which would give Enterprise a bit more time. OTOH, we also have this weird thing in The Galileo Seven where the shuttlecraft apparently doesn't have enough fuel to maintain orbit for any amount of time. This would seem to be a dialog error, since a natural orbit would still be possible and technically the shuttle should be heave itself into orbit and then coast there for a while.
I had assumed in G7 that the shuttle didn't have enough fuel to achieve a natural fixed orbit. I.e. it could only get so far up with what it had, but it wouldn't be enough without Enterprise to tractor them or whatnot. --Alex
Another vote for powered orbits. There were some stories where there there's really no other explanation.
Nothing is more subtle than two thermonuclear engines spitting out enough hot reaction mass to keep a million ton vessel stationary over a major metropolitan area during the Cold War.
I have always assume they use their engines to stay where they want, but when you mention it, it could be quite dangerous.
I aways assumed a powered orbit, given certain references to short orbital periods and the ability ot "hang" over a given ground site for long periods of time.
Here's a different approach: Is there anything in canon to support or refute the notion that a space vessel's "orbit" of a given planet could be "powered" for one instance and "natural" for the next? In other words, could the Enterprise and other vessels in TOS/TNG/etc be employing different "orbit" techniques depending on the mission and the skipper's discretion?