NASA has continued to twist itself into a pretzel over whether Boeing's CST-100 Starliner - now two months past its original return date - can be used to bring back its crew to Earth and whether a failure to do so would be classed as a mishap.

The briefing, which did not feature any Boeing personnel, hinted at the turmoil behind the scenes at the US space agency as staffers grapple with the problem of Starliner's problematic thrusters amid the knowledge that a proven and operational spacecraft, in the form of the Crew Dragon, could be pressed into service.

The question for engineers and managers is which option would pose less risk for the crew.

The wrangling means a decision on the transport method that the Starliner crew, Butch Wilmore and Suni William, will take for their trip back to Earth has been delayed once again, likely to the week after next.

During the briefing, it was noted that factors including docking port availability and the use of International Space Station (ISS) consumables meant that the last week of August would be the point where a decision - whether Wilmore and Williams become part of Crew-9 or return on Starliner -would have to be made.

For context, Boeing's Starliner has been cleared for crew return in an emergency. However, NASA is still weighing up whether it would be riskier to use it for a nominal return or simply wait for the next Crew Dragon.

Returning the Starliner crew on the Crew-8 capsule, currently docked to the ISS, hasn't been seriously considered as part of a nominal flight plan. However, NASA did explain that should a contingency event happen after Starliner left the ISS in uncrewed mode and before the Crew-9 spacecraft arrived, Wilmore and Williams would have to return to Earth unsuited. While the suits are, in theory, not required should the capsule maintain pressure during reentry, it is one more risk for NASA to balance.

The suits are not interchangeable: Boeing suits can't be used in a SpaceX vehicle and vice-versa. SpaceX suits for the Starliner crew would arrive with Crew-9.

There's an obvious comment to be made about lessons learned from the infamous Apollo 13 incident, where the Command Module's cartridges for the carbon dioxide scrubber had to be adapted for the Lunar Module, but there are doubtless very good technical reasons why SpaceX and Boeing went different ways with their suit design.

We'd welcome your explanations in the comments below.

NASA also indicated that if the Calamity Capsule's crewed flight test ended with an uncrewed landing, it wouldn't count as a mishap since NASA would have intervened and decided to remove the crew.

Right now, the primary plan remains to return the Starliner crew to Earth as planned using Boeing's spacecraft. However, as NASA engineers grapple with explaining the thruster issues, the go / no-go decision continues to move backward.

There is, it seems, finally an end in sight to the uncertainty. ®

https://www.theregister.com//2024/08/15/nasa_starliner_decision_end_august/