4 astronauts splashdown on SpaceX capsule to end Axiom Space’s private Ax-4 mission

A SpaceX capsule carrying four astronauts on the private Ax-4 mission hurtled through the Earth’s atmosphere early Tuesday, paralleling the California coast with a splashdown in the Pacific Ocean off San Diego, capping 20 days in space.

The pre-dawn return, which rattled parts of southern California with a sonic boom just before 2:31 a.m. PT, ends Axiom Space’s fourth private mission to the International Space Station where it was docked for 18 days.

The Houston, Texas-based commercial space company works with SpaceX for rides to the I.S.S. and coordinates with NASA for the usage of the station for its astronauts. Ax-4 lifted off from Florida’s Kennedy Space Center on June 25.

On this flight, the crew of four set a number of firsts:

• They flew the maiden voyage of SpaceX’s newest capsule, named Grace.
• The commander, Peggy Whitson, extended her record-setting cumulative time in space by a U.S. astronaut to 695 days. Now Axiom Space’s director of human spaceflight, the veteran former NASA astronaut made her fifth overall space trip.
• She was joined on Ax-4 by astronauts from India (pilot Shubhanshu Shukla), Poland (mission specialist Sławosz Uznański-Wiśniewski) and Hungary (mission specialist Tibor Kapu).
• Axiom Space notes it was the first time in four decades that, “these nations launched national astronauts into space — and for the first time ever, their astronauts lived and worked aboard the International Space Station.”

While at the I.S.S., the Ax-4 crew conducted approximately 60 scientific experiments and research studies. The company says it’s the “most research and science-related activities” conducted so far on an Axiom Space flight.

This was the 18th time SpaceX launched humans into orbit. The Starbase, Texas company’s next mission for NASA, Crew-11, is scheduled to launch in a few weeks from the Kennedy Space Center for a long-duration stay at the space station.

Central Florida Public Media’s Brendan Byrne contributed reporting from Orlando, Fla.