This was the first test flight of the Boeing Starliner spacecraft carrying astronauts.
But it ran into problems shortly after launching from Cape Canaveral, Florida, on June 5.
In the capsule, helium, which fuels the propulsion system, leaked, and several of the thrusters malfunctioned.
Boeing and NASA engineers worked for months to figure out the technical issues, but in late August the space agency decided Starliner was not safe enough to return astronauts to space.
“From a human perspective, we're all delighted that the landing was successful, but some of us wish things had gone as planned,” Steve Stitch said at a post-landing press conference.
“We planned to carry out the mission by taking Butch and Suni.”
“There is clearly work to be done,” he said, adding that it would take “some time” to decide what happens next.
The briefing panel consisted solely of NASA officials. Two Boeing representatives who were supposed to be present were missing.
NASA official Joel Montalbano, when asked about the non-participation, said Boeing had decided to “delegate to NASA” to take over the mission.
Instead, Boeing issued a statement “acknowledging the work the Starliner team did to ensure a successful and safe undocking, deorbit, reentry and landing.”
Boeing said it would “review the data” and determine next steps for the program.
Mr. Stitch previously He acknowledged that there was “tension in the room” between Boeing and NASA when the decision was made not to fly astronauts aboard Starliner, with Boeing insisting the spacecraft could carry two people and return safely.
“The NASA team couldn't rest on that because of the uncertainties and the modeling,” he said.
Plans to use rival SpaceX have significantly delayed the return of astronauts.
The extra time is to allow SpaceX to launch its next rocket, which is scheduled for liftoff in late September.
Originally intended to carry four astronauts, it will carry two instead, which will create room for Butch and Suni to ride together on the vehicle to return to Earth when their planned stay ends in February next year.
