Why are two Boeing astronauts stuck in space?

A series of problems with the new Boeing CST-100 Starliner spacecraft has delayed their return from the International Space Station.

Two NASA-trained astronauts who were testing Boeing’s new CST-100 Starliner spacecraft have been forced to remain aboard the International Space Station (ISS) orbiting the Earth some 400km (250 miles) after experiencing technical difficulties with their spacecraft.

Astronauts Suni Williams and Butch Wilmore were originally scheduled to return to Earth on June 13, after their Boeing Starliner capsule launched its first crewed flight from Florida’s Cape Canaveral Space Force Station on June 5. But the Starliner has been plagued with issues, even before the June 5 launch. A previous launch attempt was scrapped on June 1 just moments before launch because of a ground control computer performance issue.

During the 25-hour flight to the International Space Station, the spacecraft experienced several helium leaks and a malfunctioning thruster. Then, when the Starliner arrived on June 6 and attempted to dock at the ISS, four more of the 28 thrusters malfunctioned causing the ship’s arrival to be delayed.

According to a Boeing spokesperson, four of the five thrusters that previously malfunctioned are now operating normally. “This means only one thruster out of 27 is currently offline. This does not present an issue for the return mission,” the spokesperson added.

Sunita “Suni” Williams is an American astronaut and US Navy officer who joined NASA in 1998. Williams made her first spaceflight to the ISS to service electricity-generating solar array panels on the Space Shuttle Discovery (STS-116) in December 2006, when she was a flight engineer. Her second mission in May 2012 as a flight engineer was on Expedition 32 to the ISS to test a new microsatellite deployment system. After completing other missions, Williams was one of the first astronauts selected to train for NASA’s Commercial Crew Program in 2015.