Two astronauts testing Boeing’s new Starliner spacecraft were scheduled to return to Earth on Wednesday night but will now remain on the International Space Station (ISS) due to ongoing technical issues. The spacecraft's return had already been delayed because of problems with some thrusters and helium gas leaks, which are used to push fuel into the propulsion system.
NASA is conducting a high-level review to address these technical problems before deciding on the new return date for astronauts Suni Williams and Butch Wilmore, who are not in any danger. The Starliner, launched on June 5, had a minor helium leak that engineers believed would not impact the mission. However, four additional leaks developed, and five out of 28 maneuvering thrusters failed during the approach to the ISS, although four were restarted.
Originally an eight-day mission, the return was postponed to investigate the issues. On June 18, NASA announced the return would begin at 22:00 EST on Wednesday, June 26 (03:00 Thursday, June 27 BST). Despite previous assurances that the helium leaks posed no safety risk, a high-level review prompted NASA to adjust the return date to July without providing further details.
NASA aims to thoroughly investigate the spacecraft’s faults before re-entry, as the service module will burn up upon re-entry, potentially losing critical information. The astronauts are not stranded, as Starliner is certified for emergency return to Earth. The decision on the next steps depends on an “agency level review” by NASA, raising questions about whether the initial launch should have proceeded despite the leak.
Dr. Adam Baker, head of Rocket Engineering, a UK company specializing in rocket propulsion systems, acknowledges the rationale for launching but suggests it would have been better to identify and repair the leak beforehand. He notes the risk of striving for perfection leading to delays and increased costs, possibly diminishing public and political support. However, he believes NASA and Boeing should have considered the potential worsening of the leak post-launch.
Addressing the issue would have been costly, requiring the rocket's removal from the launch pad and propulsion system extraction. Another concern is why these problems were not identified in the two previous uncrewed flight tests, according to Dr. Simeon Barber, a space scientist at the Open University. He emphasizes that the current issues are unexpected at this stage of Starliner’s development.
Identifying the root cause of the helium leaks and thruster problems is critical for NASA. Without understanding the failure's root cause, risk analyses and contingency plans remain incomplete. Dr. Barber stresses the importance of ensuring there are no systematic problems affecting both the primary propulsion system and backups.
As a last resort, NASA and Boeing can return the astronauts on SpaceX’s Dragon capsule, although this would be embarrassing for Boeing. However, Dr. Baker believes this situation is an expected part of new spacecraft development and is not a major concern, as long as it is analyzed and resolved before the next crewed flight.