1990s

KIRK: We're reading it, Lieutenant. I thought you said it couldn't possibly be an Earth vessel.

SPOCK: I fail to understand why it always gives you pleasure to see me proven wrong.

KIRK: An emotional Earth weakness of mine. There it is.

KIRK: An old Earth vessel, similar to the DY-500 class.

SPOCK: Much older. DY-100 class, to be exact. Captain, the last such vessel was built centuries ago, back in the 1990s.

KIRK: Then it's a derelict, its signal left on automatic.

SPOCK: Or an old Earth ship being used by aliens.