Star Trek: Picard debuted its first season finale this week on CBS All Access. The episode included the return of Capt. William Riker to active Starfleet duty. Riker returned to duty to lead the Starfleet squadron responding to Captain Jean-Luc Picard's distress call, but he wasn't commanding the USS Titan, the ship he left the Enterprise to captain in Star Trek: Nemesis. Instead, he was acting captain of the Curiosity-class USS Zheng He. Responding to fan question on Instagram, Picard showrunner Michael Chabon revealed why Riker wasn't back aboard the Titan. He notes the number of years that have passed since Nemesis took place and since Riker retired from active duty, as well as the timing and nature of this mission.
"Assuming that the Titan is still in service — probably a reasonable assumption — she's nearly a decade in Riker's rear-view, and he in hers," Chabon says. "It's off somewhere in the galaxy exploring strange new worlds, seeking out new life, etc. This brand new Curiosity-class ship was freshly crewed up and ready to go."
Riker departing the USS Enterprise-E to take command of the USS Titan after marrying Deanna Troi, who would join him on the Titan, was a subplot of Star Trek: Nemesis, the final Star Trek: The Next Generation movie. The ship has never appeared in canon, but a series of interconnected Star Trek novels continues to follow the ship's adventures under Riker's command after the events of Nemesis.
Riker's new ship is the USS Zheng He. The ship is named after a 15th-century Chinese explorer. In addition to being an accomplished mariner, Zheng He commanded the Ming Dynasty's treasure ships, which were referred to as the "Star Fleet."
Some aspects of the ship may look familiar. The Zheng He's bridge is a redress of the USS Discovery bridge set at Star Trek: Discovery's production site in Toronto. The layout is the same, but the screens have been altered to show era-appropriate LCARS displays and the captain's chair has been altered slightly.
The exterior of the Zheng He, a Curiosity-class vessel, resembles some ships from the game Star Trek Online. It isn't exactly like any of the game's ships, as was the case with Admiral Picard's new ship, but the overall aesthetic is similar. I would come as no surprise to see Curiosity-class ships are added to Star Trek Online in an update in the near future.