Summary
NASA and Boeing plan an uncrewed Starliner-1 flight to evaluate propulsion-system changes before a crewed return mission currently planned for 2028. NASA also intends to add two Starliner station flights and certify Vulcan for crew transport.
NASA and Boeing said on Sept. 28 that Starliner will make an uncrewed engineering flight before the companies complete work toward crewed missions. NASA says Starliner-1 could fly in December 2026 or January 2027; the agency’s current plan is to return astronauts to the International Space Station on Starliner-2 by 2028.
The next flight is intended to evaluate changes made after problems with the spacecraft’s service-module thrusters during Starliner’s first crewed flight in 2024. NASA also intends to exercise options for a fifth and sixth Starliner flight to and from the station, and will work with Boeing and United Launch Alliance to certify the Vulcan rocket for crew transport after Atlas V’s final flight.
Starliner-1 will test propulsion changes without a crew
NASA’s Program Investigation Team identified 61 recommendations after the 2024 flight, which ended with Starliner returning to Earth uncrewed. The investigation found that the service-module reaction-control thrusters had operated outside their engineering qualification, contributing to a loss of control. NASA and Boeing said ground testing and analysis pointed to a combination of the thermal environment and features of the thruster design as factors in the performance problems.
Reaction-control thrusters help a spacecraft control its orientation and movement. Boeing has made thermal modifications to Starliner’s service module, which NASA plans to evaluate on Starliner-1. The flight is designed to check the improved thermal environment, gather performance data needed for system qualification and identify residual risk before crewed missions.
NASA and Boeing have also agreed to a further change to the service-module thruster valves. The modification, to be completed after Starliner-1, is intended to address poppet-seal extrusion and its effects on thruster performance. The uncrewed flight will therefore provide engineering data before that valve change is incorporated for certification and future crewed flights.
Certification work will continue after the test flight
Boeing plans additional spacecraft changes, including new thrusters in the crew module, new batteries and minor parachute-system modifications intended to improve performance and reliability. NASA says the flight data, corrective actions and required testing will inform certification for crewed operations. The agency has described Starliner-2 as the planned crewed return mission, with astronauts expected to fly by 2028.
NASA says maintaining more than one U.S. crew-transportation option is important for continued access to space, the eventual transition from the International Space Station to commercial stations, and wider commercial activity in low Earth orbit. The expanded Starliner flight options and planned Vulcan certification are part of that effort; the immediate step is an uncrewed test of the spacecraft’s propulsion changes.