As STAR TREK: DISCOVERY begins rehearsals this week in anticipation of next week’s launch of filming, CBS has confirmed today that the series — rescheduled from January to May 2017 back in September — is now warping off the springtime CBS All Access Schedule.

In a statement released to multiple media outlets today (including Variety), CBS made the following comments regarding this second delay:

Production on ‘Star Trek: Discovery’ begins next week. We love the cast, the scripts and are excited about the world the producers have created. This is an ambitious project; we will be flexible on a launch date if it’s best for the show.

We’ve said from the beginning it’s more important to do this right than to do it fast. There is also added flexibility presenting on CBS All Access, which isn’t beholden to seasonal premieres or launch windows.

While this additional push-out of the DISCOVERY debut will likely be a disappointment to fans, EW’s James Hibberd offered the following commentary which may factor into the reason for a new shift:

This switch has a few reasons behind it, a key one is that recently cast star Sonequa Martin-Green is on AMC’s mega-hit The Walking Dead, which is airing its current season through April. There’s a concern about marketplace confusion if CBS were to ramp up promoting her as the star of a new sci-fi show while her horror hit is currently on the air.

The other reason is there’s still a lot of careful deliberation continuing to go into making Discovery special, from the choice of directors, to set design, to the special effects. While May would have been a strong premiere month for the project since Discovery will launch on the CBS broadcast network before moving to the streaming service (May is a ratings surge month), given that Discovery will normally live on All-Access, there’s no pressure to fill a specific time slot.

That being said, we now do not know when CBS plans to release the series – but with filming just days away, we’re likely to hear another debut projection from CBS before too long.

In addition to the calendar changes, CBS also announced this morning that English actor James Frain has been cast as Sarek (son of Skon, son of Solkar) in the new series, making him the fourth actor to portray the Vulcan Ambassador – and father of Spock – in the Trek franchise.

More notably, however, this casting brings the first previously-known Trek character into the DISCOVERY fold, connecting back to Bryan Fuller’s comments back in August that Amanda Grayson “maybe” will factor into the show (though while there’s been no word on that character’s official appearance, having Sarek around will open that door quite easily).

Frain has been most recently spotted on Gotham, True Detective, and the genre favorite Orphan Black (video above).

Meanwhile, we’re still waiting official CBS confirmation of Sonequa Martin-Green’s casting in the lead role, widely reported by multiple outlets in December.