WASHINGTON — A delayed launch of commercial satellites on a Falcon Heavy could upend the schedule of flights to the International Space Station, including a private astronaut mission that was scheduled for early May.

During an April 24 briefing about an upcoming ISS spacewalk, a NASA official said the Ax-2 mission to the station by Axiom Space, which had been scheduled for as soon as May 8, would likely be pushed back.

“We’re trying to determine the best launch date right now for the Axiom mission,” said Dina Contella, operations integration manager for the ISS at NASA. “We’re currently just looking at what our options are.”

She said later in the briefing that the review is linked to delays in the Falcon Heavy launch of the ViaSat-3 Americas and Astranis Arcturus satellites from Launch Complex 39A at the Kennedy Space Center. The launch, previously scheduled for April 18, was delayed to April 26 by SpaceX several days after a static-fire test of the rocket’s three boosters. The company did not disclose the reason for the delay.

That pad is also used for Falcon 9 cargo and crew missions to the ISS, but requires some work to change over from Falcon Heavy to crewed Falcon 9 launches. “We will be having to figure out a new launch date for Axiom based on the turnaround of the pad,” Contella said. She said NASA was in discussions with SpaceX and Axiom Space about a new launch date, which could be announced in the next few days.

There is limited flexibility for rescheduling Ax-2, a 10-day mission to the ISS on a Crew Dragon that will carry four private astronauts, including two from Saudi Arabia. A cargo mission, SpaceX CRS-28, is currently scheduled to launch June 3, and Contella said that NASA would like to keep that cargo mission on schedule.

“We’re trying to, if we can, leave SpaceX CRS-28 on June 3,” she said. That mission is carrying another pair of new solar arrays for the station that will be installed on two spacewalks. NASA wants to complete those spacewalks by early July, when the station enters a “high beta” period with extended illumination of the station. “If we can complete that whole mission before the high beta, that would be preferred.”

It’s unclear what will happen if Ax-2 cannot be rescheduled for the CRS-28 cargo mission. Shortly after CRS-28 is the Crew Flight Test mission of Boeing’s CST-100 Starliner, currently scheduled for July 21, followed in mid-August by Crew-7, a Crew Dragon mission for NASA. The agency confirmed the dates for those two later launches April 14 in a manifest that also includes Crew-8 in February 2024 and Starliner-1 in mid-2024.

Contella added that NASA is also hoping to launch another Cygnus mission, NG-19, to the station some time this summer. The NG-18 Cygnus was unberthed by the station’s robotic arm and released April 21, later reentering. Cygnus, though, uses a different port than the two docking ports for Dragon, Crew Dragon and Starliner spacecraft, giving NASA more schedule flexibility.

The April 28 spacewalk, by NASA astronaut Steve Bowen and UAE astronaut Sultan Alneyadi, will do some preparatory work for those upcoming solar array spacewalks, including installing cables and fixing insulation “that’s not exactly in the right configuration,” Contella said. They will set up equipment during their spacewalk “so the June spacewalks can go off as planned.”

Bowen and Alneyadi will also retrieve a large S-band antenna, taking it inside the station so it can be returned to Earth for refurbishment. The spacewalk will be the first by Alneyadi or any Emirati astronaut and the eighth by Bowen.

Those activities will take place as engineers continue to review data from coolant leaks suffered in December by a Soyuz spacecraft and in February by a Progress spacecraft, both while docked to the station.

“We don’t have any new news to report” on the Roscosmos investigation into the leaks, she said, including whether the two leaks had a common cause. “They are investigating and we are closely working with them.”

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...