WASHINGTON — NASA gave its approval Dec. 12 to proceed with the launch later this month of Boeing’s CST-100 Starliner commercial crew spacecraft on an uncrewed test flight to the International Space Station.

At the end of a Flight Readiness Review at the Kennedy Space Center, NASA officials approved plans to launch the Starliner on its Orbital Flight Test (OFT) mission on a United Launch Alliance Atlas 5 at 6:36 a.m. Eastern Dec. 20. A launch on that day would result in the spacecraft docking with the ISS a little more than a day later, remaining there for nearly a week before landing at White Sands Missile Range in New Mexico in the predawn hours of Dec. 28.

“I’m happy to announce we’re go for launch,” NASA Deputy Administrator Jim Morhard said in a media teleconference shortly after the review concluded.

Phil McAlister, director of commercial spaceflight development at NASA, said there was still some “standard open work” to complete ahead of that launch, as well as resolve two open issues. “We could move off the 20th, but right now the 20th is looking good,” he said.

Those open issues, said John Mulholland, vice president and program manager of Boeing’s commercial crew program, include finalizing a review by the ISS program to confirm the Starliner flying on the mission matches the previously approved design, as well as final “data loads” for the spacecraft. Both of those, he said, should be completed before the scheduled Dec. 20 launch.

In the meantime, launch preparations will continue, including a final cargo load into the spacecraft Dec. 14 and rollout of the Atlas 5 with Starliner to the pad at Cape Canaveral’s Launch Complex 41 on Dec. 17. Starliner will be carrying an anthropomorphic test dummy, nicknamed Rosie, that will be instrumented to measure the conditions astronauts will experience on the vehicle. “And, absolutely, as we approach the holidays, we will be bringing presents for the crew,” Mulholland added.

Assuming the launch does take place Dec. 20, the spacecraft would dock with the station at 8:08 a.m. Eastern Dec. 21, with undocking at 2:16 a.m. Eastern Dec. 28. The nearly week-long stay, Mulholland said, is driven primarily by the requirement that there be two landing sites in the western U.S. available on consecutive days for the landing, adding that the fact the landing will be taking place at night — 5:48 a.m. Eastern — is not an issue.

If the launch doesn’t take place during the instantaneous launch window on Dec. 20, there are backup dates reserved for Dec. 21 and 23. Should the launch not take place by Dec. 23, Mulholland said several other dates are available, including Dec. 25 through 28. “We have plenty of available launch opportunities as we look forward into December,” he said.

A successful OFT mission would allow Boeing and NASA to proceed with a crewed flight test with agency astronauts Mike Fincke and Nicole Mann, and Boeing test pilot Chris Ferguson, on board. That mission would be ready to launch in the “first part of 2020,” Mulholland said, but declined to be more specific about a potential launch date. “We’re hesitant right now to set the launch date until we get through a solid Orbital Flight Test and make sure we thoroughly review the data and understand anything we might need to do to support the Crew Flight Test,” he said.

Kathy Lueders, NASA commercial crew program manager, said that SpaceX would also be ready to fly a crewed flight test in early 2020, some time after an in-flight abort test of the Crew Dragon spacecraft currently scheduled for no earlier than Jan. 4. “They’re getting their spacecraft ready and launch vehicle ready for first quarter of 2020.”

While optimistic that Boeing and/or SpaceX will have commercial crew vehicles ready to carry astronauts in 2020, the agency remains in negotiations with the Russian state space corporation Roscosmos to obtain additional Soyuz seats to ensure NASA astronauts can remain on the station after current agreements on Soyuz seats expire in the fall of 2020.

“We don’t have a negotiation settlement yet, but certainly both parties are very interested in seeing us maintain our astronauts and their cosmonauts on the International Space Station,” NASA Administrator Jim Bridenstine said in a Dec. 10 interview.

“Building a rocket, building a spaceship is very, very difficult,” said Kirk Shireman, NASA ISS program manager, during the Dec. 12 media call when asked about the status of procuring additional Soyuz seats. “While we are definitely working very hard with Boeing and with SpaceX to fly off U.S. soil, we need to make sure that we have margin. The worst thing we could do is to rush those things, rush finishing these vehicles.”