NASA astronaut Sunita Williams stuck in space: Still no return date but engineers finally identify the potential problem

NASA and Boeing officials have not yet set a return date for the two astronauts on Boeing’s Starliner spacecraft: Sunita Williams and Butch Wilmore. This is despite recent tests to replicate and understand the issues it faced during its inaugural crewed test flight. These issues included helium leaks and thruster malfunctions on the way to the International Space Station (ISS). However, engineers have identified potential causes for these problems and are conducting additional tests to confirm their findings, according to a report by CNN.

Engineers in New Mexico conducted over 1,000 test firings of the Starliner’s thrusters, mimicking both their initial and return journey operations. These tests suggested that heat buildup inside the thrusters may cause Teflon seals to bulge, restricting propellant flow. This discovery has increased confidence in the spacecraft's ability to undock and return safely. 

Due to the findings, NASA and Boeing decided against manual control of the Starliner on the return trip, as manual maneuvering stressed the thrusters during the ISS journey. Despite the progress, it remains uncertain if the same Starliner spacecraft will be used for the return trip.

Astronauts Butch Wilmore and Suni Williams, who arrived at the ISS on June 6 for a planned week-long mission, have now been in space for about 50 days. The Starliner is designed to stay in space for a maximum of 90 days.

Further tests are being conducted to address helium leaks. Engineers believe these leaks result from seals degraded by exposure to propellant vapor. They are exploring material changes for future missions. Tests this weekend will include firing 27 of the Starliner’s thrusters while docked at the ISS to understand if the leaks have worsened.

The unresolved helium leak issue is a significant factor in the delay in setting a return date. NASA and Boeing aim to understand and manage the stability of these leaks. A review to plan for Starliner’s undocking is expected soon, possibly as early as late next week.