It's a whole family of designs. It starts with Masao Okazaki, whose fan site
The Starfleet Museum features his art on various "older" Trek ships and stations he dreamed up to create a whole history for Starfleet. When the Vanguard novels were in want of cover art on such "older" things, that is, a Starbase 47 with post-ENT but pre-TOS aesthetics, Masao got contacted, and drew the station, based on his "J Class Starbase" design. It was then also used, slightly rescaled and otherwise fine-tuned, in the TOS-R episode "Ultimate Computer" (it says "Starbase 6" on tiny letters on the side, but this can't really be seen, and the episode dialogue doesn't reveal the identity of the station), and finally makes an appearance in this LDS ep, again with mods.
However, Masao already combined the aesthetics of ST3 Spacedock with those of TOS to create the original. So the ST3 design is very much part of the same family, as are its various study models and drawings that pop up in TNG and elsewhere. And of course the top dome here is lifted from the original TOS station, a variant of the real-world "sombrero" study by Douglas Corp. for a much, much smaller space habitat launched on top of rockets, with the top domes fitting inside the nose cones... So Deep Space Station K-7 from "Trouble with Tribbles" (also originally reused in "Ultimate Computer") is part of the family, too.
Timo Saloniemi
