WASHINGTON — Delays in the completion of a new Crew Dragon spacecraft will extend the stay of astronauts on the International Space Station by a month, including two who have been there since June.

NASA announced Dec. 17 that it was delaying the launch of the Crew-10 mission to the ISS, previously scheduled for February, to no earlier than late March. NASA, in its statement, cited the need to provide additional time to complete a new Dragon spacecraft that will be used for the mission.

“Fabrication, assembly, testing, and final integration of a new spacecraft is a painstaking endeavor that requires great attention to detail,” said Steve Stich, NASA commercial crew program manager, in a statement. “We appreciate the hard work by the SpaceX team to expand the Dragon fleet in support of our missions and the flexibility of the station program and expedition crews as we work together to complete the new capsule’s readiness for flight.”

The new Crew Dragon will be the fifth in SpaceX’s fleet, along with three cargo Dragon spacecraft. “It’s almost done,” said Sarah Walker, director of Dragon mission management at SpaceX, in a July briefing. At the time she said the spacecraft was completing final work at SpaceX’s Hawthorne, California, factory and would be shipped to Florida “shortly” for final preparations. At the same briefing, Stich said the spacecraft was slated for the Crew-10 mission, then planned for February.

NASA, in its statement about the delay, said the new Crew Dragon was now expected to arrive in SpaceX’s Florida processing facility in January. The agency didn’t elaborate on specific issues that caused the delay.

NASA said it considered options, including using a different Crew Dragon spacecraft and unspecified “manifest adjustments,” before settling on the delay. In addition to the Crew Dragon spacecraft Freedom, currently at the ISS for Crew-9, two others, Endeavour and Resilience, recently returned to Earth after the Crew-8 and Polaris Dawn missions, respectively, and likely would not be ready for a February launch.

Crew-10 will still fly with the same crew: NASA astronauts Anne McClain and Nichole Ayers, JAXA astronaut Takuya Onishi and Roscosmos cosmonaut Kirill Peskov.

The delay does give extra time in space for the Crew-9 crew. That Crew Dragon launched with NASA astronaut Nick Hague and Roscosmos cosmonaut Aleksandr Gorbunov in late September. After arriving at the station, NASA astronauts Suni Williams and Butch Wilmore formally joined the crew. NASA elected in August to have Williams and Wilmore, who arrived on the station in June on Boeing’s CST-100 Starliner, to remain on the station and return the Starliner to Earth uncrewed because of concerns with the spacecraft’s thrusters.

Wilmore and Williams are frequently described as being “stuck” or “stranded” on the station, although NASA has frequently noted that two have always had the means to return to Earth in an emergency. However, this latest delay means that their time on the ISS, originally scheduled to be as short as eight days, will be extended to around 10 months, assuming a launch of Crew-10 in late March and a return of Crew-9, after a handover period on the ISS, in early April.

The plan to use a new Crew Dragon is one reason why Wilmore and Williams did not return sooner. At a briefing in September, Stich said that NASA considered various options for returning the astronauts, and concluded that doing so on Crew-9 was the best choice, one that required removing two astronauts originally assigned to the mission.

“We could schedule it a little shorter,” he said of the Crew-9 mission, having it return sooner than February to shorten the extended stay of the Starliner astronauts, “but then we’d have to have another vehicle ready.” He suggested then that preparations for the new Crew Dragon didn’t make it feasible to move up the Crew-10 launch.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...