There were glitches in its propulsion system, but Boeing’s Starliner spacecraft and the two NASA astronauts it was carrying successfully docked at the International Space Station on Thursday afternoon.
Docking at 1:34 PM ET was more than an hour later than planned, after repairs to several malfunctioning thrusters.
The Starliner’s arrival came a day after the vehicle lifted off from the Cape Canaveral Space Force Station in Florida. The docking test was a major milestone for the flight, providing the final verification that Starliner is ready to begin operational flights once a year to carry NASA crews for their six-month stay on the space station.
NASA hired Boeing to build the spacecraft as a replacement for its retired space shuttles, but the agency experienced years of costly technical problems and delays that prevented it from flying the Starliner with people on board.
Engineers expected to encounter problems during this flight, and they did.
Before launch, a small helium leak was discovered in Starliner’s propulsion system. This led to weeks of investigation.
Helium, an inert gas, is used to propel the spacecraft’s thrusters. If too much is lost, the thrusters may not work properly.
Engineers determined the leak was limited to a seal, but later discovered a “design vulnerability.” If there were a series of improbable failures in the propulsion system after disconnection, Mr.
Boeing developed a backup procedure to return the Starliner to Earth in case of unexpected failures. Boeing and NASA officials concluded that the helium leak did not need to be repaired and the spacecraft could be launched.
However, last night, two more helium leaks appeared.
The flow of helium to the leaky parts of the propulsion system was stopped, and Mr. Wilmore and Mrs. Engineers investigated the problem while Williams slept. In the morning, mission managers decided to proceed with the docking. The flow of helium was turned back on for docking maneuvers.
“Starliner currently maintains a large reserve of helium,” Boeing engineer Jim May said during NASA’s coverage of the Starliner mission. “We expect more than 90 hours of free-flight capability after the test. Currently, helium leakage is not a safety issue for the crew or the mission.
As the Starliner approached the space station, four of the Starliner’s 28 maneuver jets malfunctioned. This led to further adjustments, and the Starliner lost its first docking opportunity.
The spacecraft and astronauts waited for the next one, and approached slowly without difficulty.
After procedures to ensure the seals were airtight, it took two hours to open the hatches between the Starliner and the space station. At 3:45 p.m. ET, Ms. Williams and Mr. Wilmore emerged from the Starliner and were greeted with hugs from the other astronauts.
