NASA and Boeing have announced another delay in the return of two astronauts from the International Space Station (ISS), adding four more days to their mission aboard the Starliner spacecraft. This delay marks yet another setback in the troubled Starliner program, which has faced technical issues and delays for years.

The undocking of the Starliner spacecraft has been pushed back for the second time, with the new target date set for June 26. During a press briefing, Steve Stich, manager of NASA's Commercial Crew Program, explained that the decision was made to give the teams additional time to analyze data and ensure a safe return for the astronauts.

The Starliner capsule, launched on June 5 atop United Launch Alliance's Atlas V rocket, carried NASA astronauts Butch Wilmore and Suni Williams to the ISS. However, the docking process was fraught with difficulties. Five thrusters on the spacecraft failed during the approach, although four were eventually recovered. According to Stich, the demanding rendezvous required the thrusters to fire more frequently, causing additional heating.

Another challenge encountered by the Starliner was the development of five helium leaks, potentially related to the activity of the thrusters. However, Stich reassured reporters that the leak rates have decreased since the spacecraft docked with the ISS.

Helium is crucial for the spacecraft's thruster systems, reducing combustibility and toxicity. Stich noted that the vehicle currently has approximately 70 hours of margin for the deorbit burn, with the helium supply covering around 10% of the required time.

While the Starliner remains parked outside the ISS, ground teams are conducting tests and collecting data to ensure a safe journey back to Earth. Evaluations are being carried out on an oxidizer isolation valve in the service module, responsible for controlling the flow of oxidizer essential for fuel combustion in the thrusters.

Despite the challenges faced by the Starliner program, Stich expressed confidence that the teams now feel comfortable about the return operation. The Crewed Flight Test is a crucial part of NASA's Commercial Crew Program, aimed at transporting crew and cargo to and from the ISS under a $4.3 billion contract with Boeing.

In comparison, SpaceX, NASA's other commercial partner, has successfully launched eight crews to the space station. Boeing's Starliner, however, has encountered numerous delays and technical hiccups on its path to crewed missions. The recent mission marks the first time the vehicle carries a crew to orbit.

Mark Nappi, vice president and program manager of Boeing's Commercial Crew Program, acknowledged that this is a test flight and stated that the team is still in the process of learning about the vehicle's performance and identifying areas for improvement.

Both NASA and Boeing officials have stated that the Starliner spacecraft remains safe for reentry. However, the decision has been made to keep it docked to the ISS to conduct additional tests in orbit. The maximum mission duration for Starliner's current mission is 45 days.

Starliner's journey back to Earth is estimated to take approximately six hours, and the spacecraft is expected to land in the Utah desert. As the teams continue to address the challenges faced by the Starliner program, NASA and Boeing remain committed to ensuring the safety and success of future crewed missions.