Boeing's Starliner capsule is set to undergo critical tests this weekend to verify its ability to safely carry its two-person crew back to Earth, despite encountering problems during its mission. The unexpected helium leaks and degraded maneuvering thrusters discovered during the ship's rendezvous with the International Space Station in early June triggered extensive testing and analysis, resulting in an extension of the ship's first piloted test flight from a little over one week to nearly two months.

During this extended mission, Starliner commander Barry "Butch" Wilmore and co-pilot Sunita Williams, both experienced astronauts, have been adapting to the unforeseen circumstances and enjoying their bonus time in orbit. However, the return date for the crew is yet to be announced as the team continues to make progress, but are not quite ready to finalize the plan.

Two major technical challenges lie ahead. The tests this weekend will involve "hot firing" 27 maneuvering thrusters in the Starliner's service module to ensure their proper functioning during undocking and re-entry. Additionally, parallel testing will be conducted to confirm that the five known helium leaks in the propulsion pressurization system have not worsened. These leaks are a concern as pressurized helium is crucial for igniting the propellants that power the thrusters used to re-orient the Starliner after undocking and maintain stability during re-entry and landing.

Steve Stich, the manager of NASA's Commercial Crew Program, emphasized the significance of these tests, stating that they are an essential step in the process. Assuming no major surprises arise, a NASA flight readiness review will be conducted to outline the issues and propose a "flight rationale," demonstrating that the problems have been thoroughly understood and do not pose a credible safety threat.

The initial piloted test flight of the Starliner began on June 5, and during its rendezvous with the International Space Station, multiple helium leaks and the failure of five maneuvering thrusters were detected. Subsequent investigations revealed that the thrusters' exposure to direct sunlight and the rapid-fire burns during rendezvous played a role in their performance degradation. To determine the root cause, Boeing tested a flight thruster at a NASA facility, replicating the conditions the Starliner encountered in orbit. The analysis revealed a deformation in a Teflon seal, likely due to exposure to one of the propellants, nitrogen tetroxide. The team is currently evaluating whether this seal can withstand the remainder of the flight.

Regarding the helium leaks, Stich reported that no further deterioration had been observed during earlier in-orbit tests, and all leaks remained within acceptable limits. Additional checks on the helium system will be conducted this weekend before undocking, ensuring that all aspects are thoroughly examined and accounted for.

Another noteworthy development is the extended endurance of the Starliner's batteries in space. Initially rated for 45 days, their performance in orbit has exceeded expectations, prompting an extension to a 90-day limit. As the ship marks its 50th day in space, it is anticipated that Wilmore and Williams may return to Earth by late August, pending successful completion of upcoming tests.

Mark Nappi, Boeing's Starliner program manager, expressed confidence in the vehicle's capability to safely bring the crew back home. The next steps involve presenting the gathered information and analysis to the relevant stakeholders, leading up to the agency review scheduled for the following week.

Boeing's Starliner capsule continues to face challenges and rigorous testing as it strives to demonstrate its reliability for future crewed missions.