I would imagine that Space Station K-7, seen in the TOS ep "The Trouble with Tribbles", needs no introduction here. I was recently reviewing Geoffrey Mandel's excellent K-7 blueprints from 1976, and I noticed that the "maximum radius" of the K-class station were just a few dozen meters (yards) less than the presumed length of a Constitution-class starship. This intrigued me. There never was any canon confirmation anywhere on the actual size of the station, was there? People can compare the size of the Enterprise and the Klingon ship to the K-7 as they circle around it, and I suppose that's a vaguely logical means of making a conclusion. (If the Klingon vessel was 100 kilometers off the station, it certainly wouldn't be that close; it doesn't matter if you're going by the remastered images or the original ones.) The Mandel prints are neat, but by no means complete. This leads to questions and speculation in my mind. We hear the characters talking about shore leave, shopping, and starships using the station. We never see any spacecraft physically docking with the K-7, but we can assume it is at least possible for spacecraft of some size to do so. (I suppose it is possible that the quadrotritcale grain, bound for the troubled Sherman's Planet, could have been transmat-beamed over to the K-7's storage compartments, but we must also assume that physical docking and transfer must at least be possible as well.) I point all these things out because the way the characters keep referring to the K-7 suggests it is a "big" operation unto itself. Kinda like a commerce hub at a key point in the interstellar void. (Every spacecraft, including the station, is apparently well illuminated in both "The Trouble with Tribbles" and also in "The Ultimate Computer", at least in the original version; so we can assume K-7 and its unnamed cousin are in deep space.) The notion that the station has become a storage facility for hybrid grain interestingly suggests that the station has the capacity to do so. So K-7 (and that other one) are "big", bustling facilities in deep space, or so we may safely assume. But just how "big" is "big", anyway? There is nothing canon (outside of remastered imagery) to suggest that Cyrano Jones' one-man scoutship actually "landed" on the station, but can we make the assumption that it is at least possible? If the station can serve as a storage depot for needed grain on nearby Sherman's Planet, does that mean it can logistically serve as a storage or processing platform for other materiel? Or maybe the transfer or servicing of equipment? The notion of "shore leave" opens up the possibility that K-7 has the capacity for spacecraft, including starships-of-the-line, to allow their crews/passengers to disembark and either relax on the station or be left there as a port in a longer itinerary. This, to me, suggests that the station has the capacity to handle "passengers"/"visitors" of many hundreds, if not thousands, at a time. Remember, this isn't like an island on Earth, where you can take a walk on the beach. A space station, by definition, is an enclosed vessel with volumetric limits. So in order for K-7 to accommodate shore leave for starship crews, and storing large quantities of grain, and house its own crew, and do it all with no emergency conditions (nothing in the way K-7 personnel behaved indicated that the arrival of two starships at once, on top of handling the grain, would be a problem; in fact, issues with the Klingons and Sherman's Planet politics aside, they acted like it was business as usual) indicates (to me, at least) that there's plenty of room. The notion of Starfleet using a similar station for disembarking an entire crew for Fleet exercises suggests that it not only has the capacity but also that it has plenty of power, as well. (Obviously M-5 would have to be handled in a secure facility, and Daystrom and other Fleet V.I.P.'s would want to relax in generous accommodations as well... Plus, if we assume that these stations are isolated in an interstellar void, each of them must be secure with an ample power source for continued operations.) So, just how "big" is "big", anyway?