ORLANDO, Fla., Dec. 12 (UPI) -- Boeing's CST-100 Starliner space capsule is ready for its maiden voyage as early as Dec. 20, NASA officials said Thursday.
The space agency said the capsule passed a flight readiness review Thursday. The review included dozens of managers and engineers from the space agency, Boeing and launch provider United Launch Alliance.
The scheduled launch date is Dec. 20, but alternate dates because of potential delays go into the Christmas holiday, including Dec. 21, 23 and 25 through 28.
NASA and Boeing "are proceeding with plans for Boeing's Orbital Flight Test following the Flight Readiness Review," NASA's Commercial Crew Program said on its official Twitter account: "Launch of the CST-100 #Starliner spacecraft atop a @ULALaunch #AtlasV rocket remains scheduled for Dec. 20 at 6:36 a.m. ET."
There's a lot riding on the mission, which will be an uncrewed flight that heads from Florida to the International Space Station. Starliner has been planned for years, along with SpaceX's Crew Dragon capsule, to replace buying seats on Russian Soyuz capsules.
If all goes well, Starliner would carry astronauts to the space station in 2020 in what could be the first return to human spaceflight from U.S. soil since the space shuttle's last mission in 2011.
"We are looking forward to ending that gap," said Phil McAlister, director of NASA's commercial spaceflight development. He added, "This program will be opening up more people doing more things in space."
The spacecraft is scheduled to lift off on an Atlas V rocket from Launch Complex 41 at Cape Canaveral Air Force Station in Florida.
Officials reviewed the flight plan and redundancies built into the spacecraft systems and procedures for safety, according to a statement from NASA.
They also discussed how the data from the test flight will help prepare for the first crewed flight. Ken Bowersox, NASA's deputy associate administrator for human exploration and operations, led a readiness poll.
Starliner is smaller than Dragon, which SpaceX adapted for human use after using it for years to send cargo to the space station. Starliner is 16.5 feet high when coupled with its service module. Crew Dragon is 26.7 feet high with its trunk.
Starliner crew modules are designed to fly up to 10 missions. Service modules are made for each mission. Boeing holds a contract for two test flights and six missions to the International Space Station. Future Starliner missions depend on NASA's needs for station crews and commercial demand.
According to Boeing, Starliner is designed to fit up to seven people, but NASA missions will carry a crew of only four or five.
Boeing also plans to fly private passengers, selling an extra fifth seat on NASA missions. The company says potential customers include commercial and government-sponsored astronauts or private citizens flying as tourists.
Most flights on operational missions will be about six to 12 hours from launch to docking, but times will vary on specific missions depending on launch and rendezvous requirements.
Unlike Crew Dragon or the Apollo-era capsules, Starliner won't land in the ocean. It has parachutes and airbags to drop it into desert landing zones at White Sands Missile Range in New Mexico, Dugway Proving Ground in Utah, Willcox Playa in Arizona or at Edwards Air Force Base in California.
Both Boeing and SpaceX are more than two years behind schedule, according to their contracts awarded in 2014. Boeing successfully tested Starliner's abort system Nov. 4 at White Sands Missile Range.
The earlier abort test saw Starliner accelerate to about 650 mph in five seconds, verifying that the engines and thrusters were capable of firing in the event of an emergency while astronauts sat on the launch pad or ascended.