Boeing’s Starliner is aiming to launch its first crewed voyage on Saturday, a mission that has been a decade in the making.

The new spacecraft is expected to lift off atop an Atlas V rocket at 12:25 p.m. ET from Cape Canaveral Space Force Station in Florida. A livestream of the event will begin at 8:15 a.m. ET on NASA’s website.

Weather conditions are 90% favorable for launch, with the only concerns being winds and cumulus clouds, according to Mark Burger, launch weather officer of the 45th Weather Squadron at Cape Canaveral Space Force Station.

The mission, called Crew Flight Test, is the culmination of Boeing’s efforts to develop a spacecraft to rival SpaceX’s Crew Dragon capsule and expand US options for ferrying astronauts to the space station under NASA’s Commercial Crew Program. 

If successful, the flight would mark only the sixth inaugural journey of a crewed spacecraft in US history, NASA Administrator Bill Nelson noted in a May news conference. Riding on board will be veteran NASA astronauts Butch Wilmore and Suni Williams.

A May 6 countdown was halted just two hours before launch time due to a faulty pressure valve on the Atlas rocket. Subsequent issues, including a helium leak in Starliner’s propulsion system, have since been resolved, according to Boeing and NASA.