How long could a starship stay up in orbit?

One other point that has not been mentioned is planetary rotation. What ever the mass/volume/density of the planet, its rotational period could be just about anything. A fast-rotating planet would have a much lower altitude for a synchronous orbit. This has never really been addressed on the show, but I could imagine an earth-like planet having, say, a five hour day and still be perfectly habitable.

I dunno. It was never explored. The plain fact is that at least certain amounts of matter (buildings, surface geology, water, atmosphere) didn’t interfere with transporter technology, whatever its underlying mechanism was. Neither, apparently, did inconveniences of orbital mechanics. (No matter how high the orbit, fully 1/2 of the orbital period the ship will be on the wrong side of the planet to beam anybody up if the matter or mass of the planet were a factor. But NOT ONCE did the crew have to wait for an opportunity to beam up. It was always “call the ship, beam up immediately”.)

Thanks for the answers so far, everyone. Very interesting. I’m sure Sulu and the other Bridge crew weren’t so addled by the spores that they’d leave the Enterprise in a low-enough orbit that there would be any risk of it plunging to the planet’s surface anytime soon.

Good catch. I was going to post that, too. Perhaps the Empire has different orbital patterns…?

Was it ever established if the ship’s computer had any level of AI? It could respond to voice commands. But it never showed any sense of initiative. I’m wondering if it was self-aware enough - or if it had a built-in program - that would notice something strange like the crew disappearing and send a distress signal to Star Fleet. Or maintain orbit on its own.

Yeah, I would expect the ship to perform basic station keeping.

I think what this phenomenon represents is the fact that the show’s writers, directors and much of its audience, having reached adulthood in the 40s, was a little fuzzy on the nature of an orbit, and probably analogized it to a very high very fast airplane flight. And of course if you lose power while flying fast and high in an airplane, you do indeed start to glide down to earth. I would guess that the writers would’ve found that kind of thing attractive and natural as a plot device. If some busybody egghead pointed out that orbits don’t actually work that way, the writer and/or directory would’ve rolled his eyes and told him it’s TV shot on the cheap, not a Nobel lecture, so go away.

What’s interested is that this would no longer work for the modern audience, which is perfectly familiar with how orbits work, although they still don’t quite get Newton’s Third Law, which is why Hulk can catch an ocean liner while merely bracing himself against the curb. He’s very strong, you know, ha ha ha.

The computer acquires a personality in the episode Tomorrow is Yesterday, but this doesn’t seem to imply that it becomes sentient; in fact Kirk treats it like an annoying glitch in the software, like a badly programmed chatbot.

edit: nm, read the situation wrong.

But there was a time they couldn’t. In Return to Tomorrow, Sargon wants the crew to beam down 112 miles underground. Although Memory Alpha nor IMDB have the quote, I thought there was a line to the effect that, normally, they couldn’t beam through that much rock, but Sargon did something to make it possible.

Maybe that was a different episode? or maybe it was in Blish’s novelization but not the final script?

No indication that Kirk’s ship’s computer had AI of that level of initiative or sophistication - but eighty-some years later Picard’s ship did, in terms of being able to accept complicated shiphandling instructions and carry them out. As for sending a distress signal, Uhura sabotaged the communications system to prevent that.

Already addressed in the OP.

I dug up my copy of The Making of Star Trek and found this:

So it does appear that the computer would keep the Enterprise in orbit indefinitely, making course corrections as needed, unless it had been specifically ordered not to do so.

It might just be that it wasn’t a significant issue. The Enterprise could travel several times faster than the speed of light. Going from one side of a planet to the other would have just taken it an unnoticeable fraction of a second.

Roddenberry did run the basics past a science adviser (I’d have to look up who it was.) Even the concept of warp drive - that you couldn’t exceed the speed of light by pressing harder on the accelerator - was far in advance of any TV shows from back then.
Decaying orbits were used to build tension, not because the writers thought it was a real problem. Just like the reason you couldn’t beam our of a mess used each week.

I remember in the ST:TNG episode, Power Play, it was mentioned that the Enterprise was entering a synchronous orbit above a planet’s southern polar region. Wouldn’t this essentially mean that the ship is hanging in space and spinning like a top?

Interesting - thanks! Not canon, but good to know.

I think this thread is conclusively answered, using facts mentioned earlier.

  1. Transporter range is ~16,000 miles

  2. Geosynchronous orbit is ~22,000 miles on an earth-like planet

  3. The transporter will not work through too much matter in the way (such as the core of a planet or hundreds of miles of solid rock)

  4. The crew never has to wait for a beam-up.

The only way all 4 conditions can be true at the same time is if the ship is actually hovering over the planet under engine thrust. This is something that we can only dream of because we’d run out of rocket fuel, but Star Trek impulse engines can move the ship to a fraction of the speed of light in minutes and do not appear to run out of fuel very quickly.

If the ship’s engines fail it will immediately begin to crash.

Basically, the ship is not in orbit at all : it’s just hovering a few thousand miles up right over the away team. This is also why the ship can fire at a specific spot on the ground with it’s weaponry at will.

There are theoretical engine ideas that would give the kind of performance you would need to do this in real life, although at great cost (and of course as far as we know transporters aren’t possible that work like they do in Star Trek)

Of course, if I were designing the flight control software, I would cause it to automatically make the burns to put the ship into a stable orbit if fuel reserves were getting low instead of letting it crash.

I’d call it canonish. It’s from a book that was co-written by Gene Roddenberry.

As I recall, McCoy objected quite vociferously. Something like “That far through solid rock? Are you out of your Vulcan mind?!?”

Harvey Lynn, of the RAND Corporation. I don’t know if they ever mentioned his scientific credentials.

Hovering, yes. I don’t believe that qualifies as “geosynchronous.” There would be no need for the ship to spin at all; it would just keep its own orientation in space.