NASA and Boeing are preparing to return the Starliner spacecraft to operational service, with an uncrewed test flight to the International Space Station planned for December 2026 or January 2027, the US space agency.
NASA Administrator Jared Isaacman said the Starliner-1 mission would be used to verify modifications made following problems encountered during the spacecraft’s first crewed test flight and generate additional flight data before astronauts return aboard the vehicle.
“We are starting with an uncrewed Starliner-1 mission to the International Space Station to validate the improvements made to the spacecraft and gather the flight data we need,” Isaacman said.
NASA plans to use the results of the uncrewed mission, along with corrective measures recommended by its programme investigation team, to complete the testing and certification process required for crewed operations. The agency currently expects astronauts to fly on Starliner-2 in 2028.
The programme overhaul follows Starliner’s 2024 crewed test flight, during which astronauts Sunita “Suni” Williams and Butch Wilmore travelled to the ISS. The spacecraft subsequently returned to Earth without the astronauts following concerns over its propulsion system.
An investigation into the mission produced 61 recommendations aimed at bringing future Starliner missions in line with NASA’s human-spaceflight requirements. Investigators identified problems involving the spacecraft’s service-module reaction-control thrusters, which had operated outside their qualified engineering parameters and experienced control anomalies.
Ground testing subsequently linked the propulsion issues to the interaction between thermal conditions and aspects of the system’s design. Boeing has since incorporated thermal changes into the service module, which NASA plans to evaluate during Starliner-1.
The spacecraft is also receiving a redesigned thruster valve intended to address poppet-seal extrusion, along with upgraded crew-module thrusters, new batteries and changes to its parachute system.
Dana Weigel, manager of NASA’s Low Earth Orbit Programme, described the upcoming mission as an important stage in the certification process and in NASA’s plans for sustained human operations in low Earth orbit.
NASA also intends to exercise options for fifth and sixth Starliner missions to the ISS. In parallel, the agency is working with Boeing and United Launch Alliance to certify the Vulcan rocket for human spaceflight following the final flight of the Atlas V.
Isaacman said NASA continued to work with Boeing on addressing issues identified on earlier Starliner flights, with the broader objective of maintaining more than one US spacecraft capable of carrying astronauts to low Earth orbit.
