Astronauts from NASA, Butch Wilmore and Suni Williams, have been on the International Space Station (ISS) for several weeks after the first crewed flight of Boeing's new Starliner spacecraft encountered serious technical difficulties. Issues with thrusters and several helium leaks (which are used in the Starliner's engine system) prevented the planned return of the spacecraft.

Technical Challenges of Starliner
Before launch, a small helium leak was identified on the Starliner. Helium is an inert gas, which means it is very unreactive with other materials, making it ideal for use in contact with rocket fuel and high temperatures. A helium leak can cause insufficient fuel to reach the thrusters, which was the case during this flight. Four out of five thrusters were repaired while the spacecraft was docked to the ISS, but concerns remain for the return trip.

The helium leak problem was first discovered while the Starliner was on the launch pad, but it was deemed negligible, so the spacecraft was sent into orbit. After launch, additional leaks were discovered that prevented the use of several of the spacecraft's smaller thrusters. Upon re-entering Earth's atmosphere, the spacecraft requires a very specific "attack angle" to prevent overheating due to friction, which could result in the destruction of the spacecraft.

NASA and Boeing assure that additional thrusters and other redundancy systems are built into the spacecraft, making this scenario unlikely. However, given the severity of the helium issues, the astronauts may feel some concern.

Impact on Future Missions
The Starliner faces an additional challenge because it ejects its service module upon return, meaning crucial data about the thruster problems could be lost during re-entry into Earth's atmosphere. NASA and Boeing are currently conducting ground tests and investigations on the ISS to gather as much information as possible before the spacecraft returns.

While the astronauts remain on the ISS, their safety is a priority for both agencies. If a serious malfunction is discovered while on the ISS, there are alternative spacecraft that can safely return the crew to Earth.

History of Delays and Issues
The Starliner has been part of NASA's Commercial Crew Program since 2010, with the first crewed flight planned for 2017, but numerous delays occurred. The first successful uncrewed flight happened only in 2022, following a failed attempt in 2019. Meanwhile, SpaceX has achieved five successful crewed missions to the ISS and 30 cargo missions with its Crew Dragon.

Boeing, a long-term partner of NASA, has played a key role in the space program, including the Space Shuttle program and the development of the Space Launch System (SLS) rocket that will send astronauts to the Moon. However, the Starliner issues come at an inconvenient time for Boeing, which faces public criticism due to problems with commercial aircraft.

Meanwhile, the extended Starliner mission has allowed additional time for testing and data collection. Boeing and NASA engineers believe this additional time will provide a better understanding of the thruster behavior and the spacecraft's systems during longer missions. These tests are crucial for future operational missions lasting up to six months, the first of which is planned for 2025.

Safety Measures and Upcoming Flights
Although thruster problems have raised concerns, NASA and Boeing are conducting extensive tests to ensure the astronauts' safe return. While on the ISS, Wilmore and Williams are participating in numerous experiments and tests to ensure the Starliner is ready for future missions. The astronauts have also conducted comfort and functionality tests on the spacecraft, including emergency system checks.

The extended stay on the ISS has also allowed ground teams to conduct additional analyses and prepare for the spacecraft's return. The Starliner will return to Earth in August, ahead of the planned ISS crew replacement. The plan is for Wilmore and Williams to return before the launch of the Crew-9 mission conducted by SpaceX. The return is scheduled for the end of July or early August, depending on the test results and safety checks.

Boeing's Future Plans
Despite the current challenges, Boeing remains a key partner of NASA in space missions. Along with the continued development and testing of the Starliner, Boeing is also involved in the development of the SLS rocket, which will play a key role in the Artemis program to return humans to the Moon. These missions mark a significant step forward in space exploration and lay the foundation for future missions to Mars.

The extended mission on the ISS provides valuable data that will help improve Starliner systems and ensure astronaut safety in future missions. Boeing and NASA engineers are working intensively on data analysis and system optimization to ensure the spacecraft's successful return and preparation for future long-term missions.

These efforts demonstrate the commitment of both organizations to the safety and success of space missions, despite the technical challenges they face. With further testing and improvements, the Starliner will be ready for operational missions that will significantly contribute to space exploration and ensure the safe return of astronauts to Earth.

Despite all the challenges, the Starliner remains a key element in NASA's plan for space exploration, and efforts to improve its systems will ensure the success of future missions and the safety of all involved astronauts.

Original:
Ian Whittaker
Senior Lecturer in Physics at Nottingham Trent University