ISS crew
Despite weather delays, the ISS crew held a departure ceremony for the Ax-1 private astronauts on the space station April 19. Credit: NASA TV

WASHINGTON — Poor weather will delay the return to Earth of four private astronauts from the International Space Station, which could in turn push back the launch of the next set of NASA and ESA astronauts to the station.

The Crew Dragon spacecraft Endeavour was scheduled to undock from the ISS April 19, setting up a splashdown on the morning of April 20 off the Florida coast to conclude the Ax-1 mission to the station by Axiom Space. NASA announced April 18, though, that the undocking had been delayed to the evening of April 19, with splashdown moved to the afternoon of April 20.

The spacecraft’s departure faces further delays. NASA said April 19 the agency, working with Axiom Space and SpaceX, postponed the Crew Dragon departure, again because of weather. The agency and companies “are continuing to assess the next best opportunity for return of the first private astronaut mission to the orbiting laboratory based on weather conditions and space station operations,” NASA said in a brief statement.

Axiom Space suggested an extended delay in its own statement. “Due to unfavorable weather conditions for return, tonight’s undocking has been waved off and the crew will be spending a few more days on the space station,” the company said in an April 19 statement.

Neither NASA nor Axiom Space have stated when they expect the next opportunity to return to Earth will be. Federal Aviation Administration notices to air missions, or NOTAMs, restrict airspace at several potential splashdown locations on both April 21 and 22.

That delayed return could affect the launch of another Crew Dragon on NASA’s Crew-4 mission, currently scheduled for early April 23. NASA officials previously stated they want at least 48 hours between the Ax-1 splashdown and the Crew-4 launch to provide time for post-splashdown reviews of the Crew Dragon’s performance during reentry.

“We’ll have time to do a review between that landing and the Crew-4 launch, and we’ll preserve 48 hours in between the landing event and the launch just to make sure the recovery team is ready for the launch and that we review all that data,” Steve Stich, NASA commercial crew program manager, said at an April 15 briefing.

Despite its delayed departure, NASA and Axiom Space held a departure ceremony April 19 for the Ax-1 crew on the ISS. The four private astronauts — mission commander Michael López-Alegría and customers Larry Connor, Eytan Stibbe and Mark Pathy — arrived on the station April 9 for what was originally intended to be an eight-day stay.

López-Alegría thanked the four NASA and ESA astronauts currently on the station for being “gracious and patient” with his private astronaut crew. “They’ve shared their time, their wisdom, their food, their stories,” he said. “Especially the first couple of days, we would not have gotten through without them bailing us out on more than one occasion.”

“We hope to see a lot more PAM missions into the future,” Tom Marshburn, the NASA astronaut commanding the station, said, using NASA’s terminology for private astronaut missions (PAMs) like Ax-1. “We think we’ve accomplished a lot up here.”

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...