An international four-man crew strapped into a SpaceX capsule atop a Falcon 9 rocket at the Kennedy Space Center Tuesday for a dress-rehearsal countdown that sets the stage for launch Wednesday on a privately-funded research mission to the International Space Station.

Retired NASA astronaut Michael López-Alegría, Italian co-pilot Walter Villadei, European Space Agency astronaut Marcus Wandt of Sweden, and Turkey's Alper Gezeravci, spent the afternoon rehearsing launch-day procedures aboard their Crew Dragon spacecraft before departing the pad to clear the way for an engine test firing.

A few hours later, SpaceX engineers fired up the Falcon 9's first stage engines to verify their readiness for blastoff. If all goes well, López-Alegría and his three crewmates will strap back in Wednesday for launch at 5:11 p.m. EST, kicking off an automated one-and-a-half-day rendezvous with the space station.

During a late Tuesday teleconference, officials said the rocket and spacecraft were ready to go after last-minute fixes for a parachute issue that cropped up after a recent cargo flight and work to replace connectors holding the Crew Dragon spacecraft to the Falcon 9's upper stage that did not appear to be torqued, or tightened, to specifications.

Few details were provided, but Benji Reed, SpaceX senior director of human spaceflight programs, said the work was done in "an abundance of caution" and "we're ready to fly."

It will be the third piloted flight to the station sponsored by Houston-based Axiom Space in an ongoing NASA-sanctioned program to increase private-sector utilization of the outpost. Axiom, in turn, is using the flights to gain the experience needed to launch and operate a commercial space station after the ISS is retired at the end of the decade.

López-Alegría, one of America's most experienced astronauts, made three trips to space aboard NASA's shuttle, and once aboard a Russian Soyuz spacecraft. After retiring from NASA, he went to work for Axiom and commanded the company's first commercial mission to the ISS in April 2022. He is a citizen of both the U.S. and Spain.

His crewmates for the Ax-3 mission are all veteran European military pilots or flight engineers with extensive management experience. Wandt and Gezeravci are making their first space flight, while Villadei participated in an up-and-down trip to the edge of space last year aboard Virgin Galactic's winged sub-orbital spaceplane.

Assuming an on-time launch Wednesday, the Ax-3 fliers will dock with the space station early Friday, temporarily boosting the lab's crew to 11. During their two-week stay, the Ax-3 fliers plans to carry out more than 30 experiments primarily devoted to learning more about the effects of weightlessness on a variety of physical and cognitive parameters.

"This...is the first all-European mission with four European astronauts representing their countries as well as the European Space Agency," said Lucie Low, Axiom's chief scientist.

"So we're excited to be building on the successes of Ax-2 by continuing to expand the global microgravity research community and enabling new researchers from many countries to access microgravity for sometimes the first time."

On a lighter note, the Italian company Barilla has provided ready-made pasta that will be heated up and taste tested, Axiom says, "as part of an effort to develop a broader range of tasty foods in space for future space travelers."

Wednesday's flight will be the 12th piloted trip to orbit by SpaceX's Crew Dragon. NASA sponsored one piloted test flight and has so far sent seven long-duration crews to the station. SpaceX has launched two commercial flights to the ISS for Axiom, and one Earth-orbit mission paid for by tech entrepreneur Jared Isaacman.

In:
• Spacewalk
• International Space Station
• Space
• NASA

William Harwood

Bill Harwood has been covering the U.S. space program full-time since 1984, first as Cape Canaveral bureau chief for United Press International and now as a consultant for CBS News.

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