Starliner's Return Delayed: NASA Investigates Thruster & Leak Issues

NASA and Boeing are extending the stay of the CST-100 Starliner spacecraft at the International Space Station (ISS) to conduct a thorough analysis of in-flight anomalies. The decision to postpone the return of astronauts Butch Wilmore and Suni Williams follows the detection of multiple helium leaks in the spacecraft's propulsion system and unexpected performance from several maneuvering thrusters during its flight to the station.

Mission Context: The Crew Flight Test

The Crew Flight Test (CFT) is the inaugural crewed mission for Boeing's Starliner, a crucial step toward certifying the vehicle for regular operational flights under NASA's Commercial Crew Program. This program aims to provide redundant, safe, and reliable transportation for astronauts to and from the ISS, with SpaceX's Crew Dragon being the other certified provider.

Analyzing In-Flight Anomalies

During its journey to the ISS, mission controllers identified five small helium leaks in the service module's propulsion system, which pressurizes the propellant lines. Additionally, five of the 28 reaction control system (RCS) thrusters failed to perform as expected during the final phases of rendezvous and docking. While four of these thrusters were later recovered, engineers are working to understand the root cause of these issues before proceeding with the return flight.

1. Helium Leaks Identified: Five distinct leaks were detected in the service module's propulsion system manifolds.
2. RCS Thruster Performance: Five reaction control system thrusters experienced off-nominal performance during docking operations.
3. Data-Driven Decisions: The delay allows teams to review flight data, conduct ground tests, and develop operational procedures to ensure system integrity for undocking and re-entry.

Prioritizing Crew Safety

We are taking our time and following our standard mission management team process. We are letting the data drive our decision-making relative to managing the small helium system leaks and thruster performance we observed during rendezvous and docking.

The primary rationale for the delay is to ensure the complete safety of the crew. The RCS thrusters are critical for attitude control and performing the deorbit burn necessary for a safe return to Earth. NASA and Boeing are committed to a comprehensive review to verify the spacecraft can perform these critical maneuvers without issue.

Next Steps and Future Outlook

While docked to the ISS, the crew is not in any danger and is continuing to perform science and maintenance tasks alongside the station's Expedition crew. Mission teams on the ground will continue to analyze system performance and conduct further checkouts. A new undocking and landing date will be determined once the analysis is complete and all parties are confident in the spacecraft's readiness for the return journey.

The rigorous process being undertaken for the Starliner CFT underscores the uncompromising commitment to safety in human spaceflight. Successfully resolving these challenges is essential for establishing Starliner as a second reliable crew transportation system, strengthening NASA's capabilities for sustained operations in low-Earth orbit.