“Star Trek: Lower Decks” focuses on the support crew serving on one of Starfleet’s lesser ships, the USS Cerritos, in 2380. Ensigns Mariner, Boimler, Rutherford and Tendi must go about their duties and social lives, often while the ship is rocked by a host of sci-fi anomalies. The ship’s bridge crew includes Captain Carol Freeman, Commander Jack Ransom, Lieutenant Shaxs and Doctor T’Ana. This is the second animated spin-off in the franchise following 1973-74’s “Star Trek: The Animated Series,” but it has a decidedly more adult tone and humor.