NASA Crew-4 preps for launch but liftoff delayed as Ax-1 mission waits to leave ISS

ORLANDO, Fla., April 20 (UPI) -- NASA's next crew of astronauts planned to launch no earlier than Saturday, but space agency officials are preparing to delay the flight because of weather problems preventing the return of Axiom Space's first mission crew from the International Space Station.

The Ax-1 crew originally planned for a 10-day mission, part of the first-ever private astronaut mission to the International Space Station, which has already grown to 13 days in space as NASA's Crew-4 has prepared for it's now delayed launch.

Poor weather in the Atlantic Ocean landing zones the Axiom mission crew would splash down in has kept them at the orbital outpost for longer than expected -- and the journey grew longer on Wednesday.

The Crew-4 astronauts can't launch to ISS until Ax-1 undocks because of limited docking space for vessels on the station.

NASA's head of human spaceflight, Kathy Lueders, told UPI in a phone interview that teams were currently assessing new launch and landing dates.

"When Axiom-1 departs the space station, we will have room for Crew-4 to dock," she said. "However, we want to provide a two-day gap in between for data reviews and to prepare our launch and recovery assets."

Mike McAleenan, launch weather officer at the 45th Weather Squadron at Cape Canaveral Space Force Base, said that forecasters are keeping a close watch on the weather over the next several days.

"A strong high pressure [system] has built into Florida. This means that winds will remain high at all splashdown sites," McAleenan told UPI in a phone interview.

McAleenan said that the northern most landing sites are the most ideal at the moment, because this is where the winds will be the lightest. To that end, officials are marking the Gulf Coast and Jacksonville as the best option.

The teams have to get the timing right, however, because while those locations offer reduced wind speeds, recovery teams would have to work around morning rain showers.

While there is an urgency to bring home the crew -- Michael López-Alegría, a retired NASA astronaut and current Axiom employee; Larry Connor, a real estate and technology entrepreneur; Mark Pathy, a Canadian businessman; and Eytan Stibbe, an Israeli entrepreneur and former fighter jet pilot -- McAleenan stressed that safety is the top priority.

Despite the delay, the Crew-4 astronauts -- Kjell Lindgren, Jessica Watkins and Bob Hines of NASA, along with Italian astronaut, Samantha Cristoforetti -- continue to prepare for launch, including prelaunch dress rehearsals and test firing their rocket.

SpaceX rolled the crew's spacecraft -- a human-rated Dragon capsule named Freedom -- and rocket out to the launch pad earlier this week to start pre-launch testing.

Engineers briefly test fired the rocket's engines on Wednesday afternoon, giving it the green light to proceed toward launch whenever the weather cooperates.

The astronauts also ran through their launch-day countdown, practicing strapping into the spacecraft and preparing for liftoff.