4 minute read•Updated 6:05 PM EDT, Thu March 27, 2025
NASA and Boeing are steadily progressing toward certifying the CST-100 Starliner spacecraft for regular crewed missions, following the Crew Flight Test (CFT) to the International Space Station.
In the wake of that flight, joint teams have been working diligently to analyze in-flight data, address observed anomalies, and prepare for an extensive propulsion system test campaign set to take place over the coming months.
The collaborative effort is a critical step toward ensuring Starliner becomes a reliable, U.S.-based transportation system for astronauts traveling to and from the orbiting laboratory.
“NASA’s strategy for crew transportation is critical for assured access to space using American private industry...Our investment in commercial crew transportation capabilities is providing the needed flexibility to operate in space as safely as possible and respond to changes quickly when they arise. NASA is seeing the commitment from Boeing to adding the Starliner system to the nation’s crew transportation base.” - Ken Bowersox, Associate Administrator for Space Operations at NASA HQ
Post-Flight Progress and Remaining Challenges
Since the return of Starliner’s uncrewed capsule from orbit, teams have closed more than 70% of the observations and in-flight anomalies identified during the CFT mission. However, some of the most significant issues—particularly anomalies related to Starliner’s propulsion system—remain open and under investigation.
NASA and Boeing have committed to resolving these propulsion issues through a series of ground test campaigns planned throughout spring and summer 2025. The tests will be conducted at White Sands Test Facility in New Mexico and will include integrated thruster firings within a single service module “doghouse.” This testing aims to validate Starliner’s thermal models and determine the best approach for potential hardware upgrades and operational improvements.
Among the solutions under consideration are the installation of thermal barriers inside the thruster doghouse to better regulate heat buildup, and updates to in-flight thruster firing sequences (known as pulse profiles) to avoid overheating. In parallel, teams are also evaluating new helium seal designs to reduce the risk of leaks during future missions.
“Once we get through these planned test campaigns, we will have a better idea of when we can go fly the next Boeing flight...We’ll continue to work through certification toward the end of this year and then go figure out where Starliner fits best in the schedule for the International Space Station and its crew and cargo missions. It is likely to be in the timeframe of late this calendar year or early next year for the next Starliner flight.” - Steve Stich, manager of NASA’s Commercial Crew Program
Preparing for Starliner’s Next Mission
Looking ahead, mission planners are preparing for Starliner’s first post-certification flight, a mission that could carry crew or cargo depending on NASA’s operational needs at the time.
The flexibility to fly either payload type speaks to the modularity of the Starliner system and its potential role in supporting a variety of station operations.
The crewed flight test earlier in the program marked a significant milestone, demonstrating the vehicle’s capability to safely transport astronauts to the ISS and return them to Earth. With additional propulsion system testing and analysis underway, the upcoming certification milestones will mark the final hurdles before Starliner is cleared for long-term operational use.
NASA’s Commercial Crew Vision
The progress with Boeing’s Starliner program complements NASA’s broader Commercial Crew Program strategy, which seeks to develop two distinct U.S.-built human-rated spaceflight systems.
With SpaceX’s Crew Dragon already operational, Starliner is poised to join the mix, providing NASA with critical redundancy and flexibility in astronaut transportation.
By cultivating multiple launch providers, NASA aims to ensure uninterrupted crew access to the space station; one of the most important goals in sustaining long-duration human presence in low Earth orbit.
As Boeing and NASA continue their joint work through testing, certification, and eventual crew rotation missions, the Starliner program stands at a pivotal moment; on the verge of transitioning from test flights to operational deployment.
