NASA: Starliner astronauts not stranded on the ISS, return only later

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NASA and Boeing are still not agreeing on a date for the end of the first manned Starliner mission. The space capsule will remain docked to the International Space Station (ISS) for at least another two weeks. Further tests will be carried out during this time. The two astronauts should have returned to Earth in mid-June, but various problems have arisen, which the US space agency and Boeing are trying to understand.

Boeing's Starliner reached the ISS on June 6, with a slight delay. Like the launch of the first manned mission with this spacecraft, docking with the ISS was delayed due to technical problems, albeit only by 80 minutes. This was due to problems with the engines. It was not until the second docking maneuver that everything went smoothly, and the two astronauts were able to board the ISS shortly afterward.

Initially, the Starliner mission was extended by a few days for further testing of Boeing's spacecraft. For example, the spacecraft's propulsion system was to be examined while docked. But shortly before the already delayed return flight, the return of Boeing's Starliner to Earth was postponed – indefinitely.

Mission extended into the second half of July

NASA has now announced that the two astronauts Butch Wilmore and Suni Williams will remain on the ISS for at least two more weeks. This will give NASA and Boeing engineers on Earth more time to test the Starliner engines. Docking with the ISS had been slightly delayed because of these engines. Five had been automatically deactivated by the spacecraft's computer because their readings were outside the permissible limits. It is still unclear why the engines went offline.

Four of these engines functioned correctly during a test of the Starliner docked with the ISS in mid-June and have been released for the rest of the mission. However, the engineers are not certain that the engines fired at full power, as this took place when the spacecraft was docked. NASA will therefore test the identical engines again on Earth and simulate the situations in space.

NASA wants safety before return flight

"It gives us potentially 100 percent assurance that everything we've seen in orbit is OK," NASA manager Steve Stich explained. "It's just one more piece of data we have before we actually deorbit the vehicle." This is because, unlike the crew module, the Starliner service module with the engines will not return to Earth, but will burn up on re-entry into the atmosphere, meaning that the engines cannot be examined retrospectively.

At the same time, NASA emphasizes that the Starliner astronauts are not stranded on the ISS. Everything will be done to ensure that they return to Earth with Starliner. The ISS has sufficient space and resources for their stay. In an emergency on the ISS, whether for safety or medical reasons, Starliner could also fly back immediately. NASA has not yet approved the spacecraft for return under normal conditions.

Battery life and helium leaks

Although Starliner's batteries are originally only certified for a mission of 45 days, NASA says that this is not a problem due to the performance of the batteries so far, so the mission may well last longer. The previously registered helium leaks would also be investigated further on Earth, but the valves of the Starliner docked to the ISS were closed so that the leaks are temporarily sealed. The valves would not be opened again until the return flight and, according to NASA, Starliner has ten times the amount of helium required for the return flight.

NASA would not say at this stage when exactly Boeing's Starliner will return to Earth. "We have the luxury of time," said Ken Bowersox from NASA. "We're still in the middle of a test mission. We're still pushing things forward." Steve Stich added: "Once testing is complete, we'll look at the plan for landing. We don't have a target date today."

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