And consider they are making their first encounter with Khan aboard a drifting sleeper ship with suitably warm breathable atmosphere, lighting and artificial gravity, (!!!) all of which works after (at least) 200 years.
I choose to believe that the cylindrical portion of the ship contained a 2001
-style centrifuge which produced the gravity.
Another thing to consider: Kirk said at the end that their heading took them near Ceti Alpha, so presumably they were somewhere in that general vicinity already. Now, Alpha Ceti (as it's more properly called) is about 250 light-years away, give or take -- and the Botany Bay
was a sublight ship. So assuming they were within, say, 20 ly of Alpha Ceti, then "Space Seed" couldn't have taken place any earlier than 2226 or so.
If we go with the currently accepted date of 2267 for the episode, that's 271 years to cover somewhere around 250 ly, which gives a velocity of somewhere around 93% of lightspeed. At that speed, the time dilation factor would be just about 2.7, so 270-ish years externally would only be 100 years aboard ship, which could help explain why the power was still working. Although it means that getting the Enterprise
to match velocities with the BB would've been rather more involved than was shown.
IIRC, Golstein & Golstein's "Star Trek Space Flight Chronology" from 1980 seemed rotted in the notion that TOS was set in the late 22nd century, so obviously the authors took their cues from the canon dialogue in the series.
According to Memory Beta
, the SFC timeline put TOS in 2207-10 -- early 23rd, not late 22nd. As I said above, they were trying to reconcile the "Space Seed" reference with the references to the 23rd century that some texts had previously made, so they put it as early in the 23rd century as they could.
For quite a while in the late '70's, I subscribed to this view as well. TMP seemed to shatter this house of cards when Decker suggested that Voyager VI "was launched from Earth more than 300 years ago". (That's from my memory... anybody have an exact transcription? I suspect that's the first clear mention in canon that would set TMP in the late 23rd century)
I must've overlooked that reference, because I clung to the SFC chronology (approximately) until TNG: "The Neutral Zone" gave a 2364 date onscreen.