“Such Sweet Sorrow” has Burnham preparing to make a giant sacrifice. The sphere and the Discovery have merged, making it impossible to destroy, while Leland and Control are speeding to come get the data. As Spock says, “Discovery’s very existence is the problem.”

Burnham proposes using the crystal to “take the data out of this time,” meaning, “Discovery has to go to the future.” But of course, Burnham is the one who must go to the future without a certain path back to the present. Spock deduces that there is more than one Red Angel — one of them being Burnham.

A new signal appears that leads the Discovery to Xahea, to the delight of Tilly. Xahea, you might remember, was the focus of one of the “Short Trek” episodes from before the official second season of “Discovery.” The queen of Xahea, Po, is a 17-year-old who developed technology to recrystallize dilithium, which comes in handy in creating the supernova necessary to launch Burnham and the Discovery into the future.

Burnham’s crewmates, in a show of loyalty, commit to going with her into the future, suggesting that we might never see the Discovery crew again — unless the rest of the show takes place in the future. (Curiously, Pike offers to wear the suit in the first part of the episode but doesn’t offer to go later on. I was also surprised that Grayson and Sarek didn’t offer to go as well.)

The problem here is a self-created one by the “Discovery” writing team: Much of the episode features emotional goodbyes, but as we’ve seen, characters too often appear to get killed off only to return. And in this case, Spock is one of the crew who says he’ll go with Burnham to the future — and we know that this actually doesn’t happen, unless we are just wholly disregarding Trek canon.