Boeing's Starliner set up for third shot at first human spaceflight

A pair of NASA astronauts will try again on Wednesday morning to take a ride on Boeing's CST-100 Starliner, making its first-ever human spaceflight.

Butch Wilmore and Suni Williams have already suited up and climbed on board the spacecraft twice in the last month, but will try for a third time with a launch attempt set for 10:52 a.m. atop a United Launch Alliance Atlas V rocket from Cape Canaveral Space Force Station's Space Launch Complex 41.

Space Launch Delta 45's weather squadron forecasts a 90% chance for good conditions.

The most recent attempt on Saturday came within four minutes of liftoff, but an issue with ULA's computer system at the launch pad forced the scrub.

"The disappointment lasts for about three seconds," said ULA President and CEO Tory Bruno after the scrub. "We've been at this a long time and you just immediately get busy and do your job, and we'll be back."

Teams have since replaced the launch computer hardware, setting up the latest attempt. A May 6 attempt was scrubbed because of a fluttering valve on the ULA rocket's upper Centaur stage, also since replaced, while Boeing and NASA had to sign off on the safety of a small helium leak on Starliner's propulsion module that they ultimately decided not to fix.

"I kind of use the analogy of sports," said Boeing's Mark Nappi, vice president of its commercial crew program. "You're playing a game and you get a bad call, and you're a little irritated at first, or a little frustrated at first, but you immediately focus on the next pitch. And that's what our teams do. They're focused on the next pitch."

If they manage to lift off, the astronauts will spend just over 24 hours making their way to the International Space Station where they will spend about eight days on board before returning to Earth for a landing in the desert in the southwestern United States.

Dubbed the Crew Flight Test, it's the final required mission for Boeing under NASA's Commercial Crew Program to achieve certification and set up regular rotational missions to the ISS, sharing duties with SpaceX. Wilmore and Williams will spend time on both the way up and down from the ISS testing out manual control overrides among other facets of the mostly automated spacecraft.

The flight comes just over four years since SpaceX made its first crewed flight to the ISS with its Crew Dragon spacecraft, which has since flown 13 times carrying 50 humans to space. That includes the four members of Crew-8 awaiting along with the rest of the seven-person crew of Expedition 71 aboard the ISS.

ISS crew members Jeanette Epps and Tracy Dyson recorded a message for Williams and Wilmore ahead of their last attempt to launch this past Saturday.

"We can't wait for you guys to join us here on station," Dyson said. "We'll be monitoring your every move on the journey and we'll be waiting to open the hatch and welcome you to your home away from home."

"We know you've waited a while to get your ride aboard Starliner, but we know it will have been worth every minute," Epps added. "So from all of us on the International Space Station, godspeed and we'll see you soon."

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