Just a couple of quick notes until I can do some catch-up this weekend (hopefully).
1. The comments field seems to have become a de facto debate arena in the recent post on extremism, but for that purpose it's pretty clunky.
2. Yet another new face has been added. Expect even more cool posts here soon.
3. I was watching "Homefront"[DSN4] a few weeks ago and, as always, wondered where Spacedock had gone, since it was never mentioned while Earth's power systems were knocked out. Everyone was making use of the Lakota as if it was the only Starfleet item in orbit. This sort of thing . . . plus the fact that we generally never heard of or saw Spacedock at all throughout the TNG era . . . has led people (myself included) to wonder if Spacedock was even there anymore.
Of course, while Spacedock is almost certainly the biggest example of objects in Earth orbit, it isn't the only one. Earth orbit was a hub of activity in TMP, with orbital offices and drydocks galore. We've also heard of orbital habitats built by Sisko before DS9, and we've seen another drydock in Earth orbit as of Nemesis. That last bit kills the notion that all the Starfleet orbital stuff had been moved to Mars, where various large stations and drydock facilities have been seen.
Unless we're supposed to believe that Earth orbit has been cleared since the TMP era save for a drydock and some orbiting apartment buildings, then we can't simply assume that Spacedock isn't there simply because of a lack of mention.
. . . Or so I was thinking. It then occurred to me that there actually had been a mention of Earth Spacedock. In "Non Sequitur"[VOY2], Kim is trapped in a timeline that diverged from the "real" one starting several months before the episode (which was a Season 1 holdover set in 2371). He and the alternate-Paris steal a ship Kim designed from Spacedock.
So, at least as of a week or so before Voyager's departure in mid-2371 (which is when Kim signed on for the ship's mission per Pathways), Spacedock did exist. Unless something freaky happened in the intervening year, Spacedock was still there during the "Homefront" events.
Why it wasn't mentioned or used at all is another question altogether.
4. For some reason I was thinking that there was a shot of one of the huge Federation mushroom starbases like Starbase 74 (the upscaled Spacedock-style bases), one which did not have the planetary disc behind it as was seen in the original ST3 shot, and that further this base might've been "merely" of Spacedock size.
Evidently I'm either senile or have been hitting the crack pipe again, since a quick check of DITL and TrekCore.com's episode screenshots confirms that the shots of Starbase 133 and Lya Station Alpha used the TNG-modified ST3 shots as seen in the original Starbase 74 ep, "11001001"[TNG1]. Those all have the remarkably-Earth-like planet behind them.
This means, though, that every time we've seen one of those large-scale bases it has been in orbit of a Class M planet. The various "freestanding" bases have all been of the Regula-looking type (either Regula-size or of the larger 173/375 configurations).
I don't know about you, but if I've built a structure weighing in the neighborhood of 40-140 billion tonnes, I'd rather not put it anywhere where (a) it is subjected to the slightest gravity shear across its bulk or (b) it is remotely possible that it will go crashing down onto a populated planet. I mean, these things aren't in LEO, skirting the atmosphere and needing frequent boosts . . . but they aren't exactly out in stable L4 or L5 Trojan-style LaGrange positions either.
Assuming there are no such bases in open space, this implies that that type of base is dependent on the planet in some manner. Either (a) they aren't sufficiently self-sustaining in regards to basic supplies, crew support, materiel, et cetera, (b) they are specialized bases requiring certain supplies or manufacturing from below (kind of like Terok Nor's original purpose as an ore processing station before becoming DS9), or (c) other. Further pondering seems prudent.