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.
The capsule’s safe return put a less unhappy ending to the mission, which was able to complete many but not all of its objectives. The mission was an important step in NASA’s efforts to resume human spaceflight from the United States. Agency officials said it was too early to decide whether the next flight of Starliner will include astronauts on board as currently planned.
The capsule, which was built to resume launches of astronauts from the United States, was forced to end its crewless test flight early because a problem with its internal clock right after launch on Friday put it into the wrong orbit. That led to unexpected firing of the maneuvering thrusters, which depleted propellant and precluded the possibility of docking with the International Space Station.
About half an hour before landing, it fired thrusters for 55 seconds to drop out of orbit. That set off an automated choreography — jettisoning pieces no longer needed, deploying parachutes, inflating the airbags — to precisely aim at the landing site.
What went wrong 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 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,” Jim Chilton, senior vice president of the space and launch division at Boeing, said during a news conference on Saturday, “and being autonomous, started to behave that way.”
That caused it to use much more propellant than was expected. Its communications antennas also were not pointed in the correct position, which meant it did not immediately receive corrective commands from Boeing’s flight controllers on Earth. Because of the initial problem, not enough propellant remained to rendezvous and dock with the space station.
How did Starliner get the wrong time?
“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 by the United Launch Alliance.
If there were astronauts aboard, would they have been in danger?
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.
Did Boeing fix the problem?
Flight controllers were 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 is lower than the International Space Station, which is at an altitude of about 250 miles.
Mr. Chilton said the spacecraft’s propulsion, navigation and life support systems operatied well.
What will happen next after Starliner lands?
Boeing and NASA will investigate what went wrong and fix it.
Although the current mission could not perform all of its tasks, the two portions of greatest danger to astronauts — launch and return to Earth — have now been demonstrated.
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 testing of Apollo capsules, requiring a revamping of the design.)
The returned Starliner capsule is expected to be used again for a future mission carrying astronauts.
When will NASA be ready to fly crews to the space station again?
NASA still hopes to carry astronauts to orbit again in the first half of 2020, and has hired two companies to take astronauts to the space station, Boeing and SpaceX. Both have encountered hurdles and delays.
The problem with Boeing’s Starliner does not directly affect SpaceX’s Crew Dragon capsule. But that company still has to complete tests of its parachute and conduct an in-flight test of its abort system, currently scheduled for Jan. 11, before it is ready to carry astronauts.
Boeing had been aiming for a demonstration flight taking astronauts to the space station in the first half of 2020. But the problems on Friday’s uncrewed test may lead to further delays.
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.