Boeing’s new spacecraft, the CST-100 Starliner, safely parachuted to Earth on Sunday, landing atop inflated airbags before dawn at the White Sands Missile Range in New Mexico.
“It was an absolute bull’s-eye,” said Jim Bridenstine, the NASA administrator during a news conference after the landing.
The safe and seemingly flawless return of the capsule, which did not have any people aboard, provided an upbeat ending to a mission that started unhappily when a clock problem caused the spacecraft to deplete its propellant. A planned docking at the International Space Station was called off, and the capsule returned after only two days in orbit.
How the shortened flight affects the Starliner schedule and NASA’s plans to resume launching of astronauts on American rockets from American soil is not yet known.
Diagnosing and fixing the clock problem could add delays to the commercial crew program, NASA’s strategy of relying on private companies to build spacecraft to carry astronauts to and from the space station. It is already more than two years behind its original timeline.
Jim Chilton, senior vice president of the space and launch division at Boeing, estimated that the mission obtained enough data to fulfill 85 to 90 percent of the test objectives.
“The vessel looks great,” Mr. Chilton said. “They’re telling us there’s hardly any charring, perfectly level on her airbags. And that bodes really well for reusability.”
The Starliner capsule will be transported back to Kennedy Space Center in Florida, where it will be refurbished. Each capsule is designed to fly up to 10 times, and this one is currently scheduled to head to space again, this time with astronauts, in the second half of 2020.
Before then, Boeing is to fly another test flight, but with astronauts aboard.
Steve Stich, deputy manager of the commercial crew program for NASA, said teams from the agency and Boeing will spend weeks analyzing the data.
“To me, there’s good data out there that suggests that once we go through it, maybe it’s acceptable to go, next step, fly the crewed flight test,” Mr. Stich said. “But we have to go through the data first.”
Mr. Chilton agreed that it was too early to say whether the next Starliner flight will have astronauts aboard. “We’re not in position to propose that and we don’t propose it until we know the machine is worthy,” he said.
About half an hour before landing, thrusters fired for 55 seconds to drop the spacecraft out of orbit. That set off an automated choreography — jettisoning pieces no longer needed, deploying parachutes, inflating the airbags — that appeared to unfold flawlessly. The capsule touched down in the freezing desert before sunrise near a former space shuttle runway.
“It was just picture perfect,” Sunita Williams, the NASA astronaut who is to be the commander of the next flight of this capsule. She was at White Sands as part of the team examining the capsule after landing.
At the invitation of Boeing, Ms. Williams said she would like to name the spacecraft Calypso after the ship used by Jacques Cousteau to explore the oceans.
The return of the capsule on land was unusual, at least for NASA. All previous landings of its capsules — the Mercury, Gemini and Apollo programs of the 1960s and 1970s — were in the ocean. After all, you might be safer diving into water than an expanse of sand.
But Russian astronauts have always landed on solid ground, and that approach offers advantages. Salt water corrodes metal, which would complicate plans to reuse Starliner capsules for future missions. Also, a capsule hitting an ocean wave at the wrong angle could sink. (That is what happened during the testing of Apollo capsules, requiring a revamping of the design.)
While NASA and Boeing had many reasons to celebrate on Sunday, the mission went awry in a puzzling way on Friday. Quite simply, Starliner got the time wrong.
When the spacecraft separated from the Atlas 5 rocket that lifted it to space, an incorrect clock, off by 11 hours, caused it to start firing its thrusters and try to get into the position and orientation where it thought it should be.
“She thought she was later in the mission,” Mr. Chilton said on Saturday, “and being autonomous, started to behave that way.”
Boeing does not know what went wrong.
“If I knew, it wouldn’t have happened” Mr. Chilton said. “We were surprised.”
The spacecraft’s software set its clock based on the time it received from the Atlas 5 rocket before launch, and it is still too early to tell how it pulled the incorrect information, said Mr. Chilton. He added that the problem was with the Boeing software, not with the rocket, which was built and operated by another company, the United Launch Alliance.
This flight did not have anyone on board, but NASA and Boeing officials insist that if astronauts had been in the capsule, they would have been safe. The astronauts might even have been able to take over manual control and send the spacecraft on the proper path.
Flight controllers were eventually able to send Starliner the correct time. They then performed a couple of thruster firings to raise its orbit to a circular one 155 miles above the surface. That was lower than the International Space Station, which is at an altitude of about 250 miles.
During its abbreviated time in orbit, the spacecraft’s propulsion, navigation and life support systems appeared to work well. Even though the Starliner did not go to the space station, flight controllers were able to test some of the systems needed for the rendezvous. That included establishing a communication link between the spacecraft and station and extending, then retracting a ring that would have attached to the docking port.
The two portions of the mission of greatest danger to astronauts — launch and return to Earth — have been demonstrated.
NASA still hopes to carry astronauts to orbit again in the first half of 2020, and has also hired another company, SpaceX, to take crews to the space station.
The problem with Boeing’s Starliner does not directly affect SpaceX’s capsule, Crew Dragon, which completed its first trip to and from the space station in March. But SpaceX has encountered its own hurdles and delays, and still has to complete tests of its parachute and conduct an in-flight test of its abort system, before it is ready to carry astronauts. That launch is currently scheduled for Jan. 11.
NASA has already talked to Russia about buying additional seats on the Soyuz rockets, which have been the only transportation available to astronauts to and from the International Space Station since 2011.