NASA Weighs Uncrewed Starliner Test Before Crew Flights

NASA is considering an uncrewed Boeing Starliner mission before allowing the spacecraft to carry astronauts again. The potential test follows propulsion problems during Starliner’s first crewed flight in 2024, which forced NASA to extend astronauts Barry “Butch” Wilmore and Sunita “Suni” Williams’ stay aboard the International Space Station.

The mission was originally expected to last about eight days. Instead, the astronauts remained in orbit for approximately nine months before returning to Earth aboard SpaceX’s Crew Dragon on March 18, 2025. NASA determined that bringing them home aboard Starliner presented unnecessary risk.

The decision created a major challenge for Boeing’s commercial crew program. Starliner remains important to NASA’s goal of maintaining two independent U.S. crew transportation systems alongside Crew Dragon. However, the spacecraft must complete additional engineering reviews, testing, and certification work before supporting routine astronaut missions.

An uncrewed flight could show whether design changes and corrective actions have worked. It would allow NASA to evaluate Starliner’s propulsion, software, docking, reentry, parachute, and landing systems without exposing astronauts to unresolved risks.

Starliner’s Role in NASA’s Commercial Crew Program

NASA created the Commercial Crew Program to support privately operated spacecraft that can transport astronauts to and from low Earth orbit. The program gives NASA greater transportation flexibility while encouraging commercial innovation.

Boeing’s CST-100 Starliner is one of two spacecraft developed under the program. The other is SpaceX’s Crew Dragon, which began regular crew missions to the International Space Station in 2020. Using two systems reduces NASA’s dependence on a single provider.

Starliner is designed to carry up to seven people, although NASA missions generally use smaller crews. The spacecraft consists primarily of a reusable crew module and a service module that provides propulsion and power. It launches aboard a United Launch Alliance Atlas V rocket and lands on airbags in the western United States.

Before conducting regular operational missions, Starliner must meet NASA’s human-rating and certification requirements. Those requirements cover launch safety, crew systems, guidance and navigation, propulsion, docking, communications, thermal protection, parachutes, landing, and emergency procedures.

What Happened During the 2024 Crewed Test Flight?

Starliner launched on June 5, 2024, carrying Wilmore and Williams. The Crew Flight Test was intended to demonstrate the spacecraft’s ability to transport astronauts to the International Space Station and return them safely to Earth.

The mission included launch, orbital crew operations, rendezvous and docking, life-support evaluation, manual and automated control demonstrations, undocking, reentry, and parachute-assisted landing.

NASA reported helium-system leaks and failures involving multiple reaction-control-system thrusters during Starliner’s approach to the station. The problems did not prevent docking, but they complicated the mission and prompted additional analysis.

The helium system pressurizes propellant tanks so fuel can reach the spacecraft’s thrusters. Thrusters control the spacecraft’s orientation, adjust its trajectory, support station approach, and prepare it for undocking and reentry. Even when some thrusters remain operational, NASA must determine whether sufficient performance margin exists for both normal and emergency maneuvers.

Ground testing reproduced some of the thruster behavior. NASA and Boeing investigated whether excessive heating caused internal seals to swell and restrict propellant flow. The agency also considered helium leakage, thruster redundancy, flight rules, and the spacecraft’s ability to complete a safe return.

These issues did not prove that Starliner would fail. They did mean that NASA lacked sufficient confidence in using the spacecraft to return the astronauts under the original mission plan.

Why the Astronauts Returned on Crew Dragon

NASA extended Wilmore and Williams’ stay while engineers reviewed Starliner and evaluated possible return scenarios. The International Space Station provided a safe temporary environment, although extending a mission created additional logistical and operational demands.

Starliner returned to Earth without its crew on September 6, 2024, and landed in New Mexico on September 7. Wilmore and Williams remained aboard the station and returned on March 18, 2025, as members of the Crew-9 mission aboard SpaceX’s Crew Dragon NASA.

Their extended mission lasted approximately 286 days. NASA said the decision to use Crew Dragon was based on safety and the need to maintain an appropriate crew complement aboard the station NASA.

Why NASA May Choose an Uncrewed Test

An uncrewed flight would allow NASA and Boeing to evaluate Starliner after corrective actions without placing astronauts aboard. Potential objectives include:

• Testing thruster performance under flight conditions.
• Monitoring helium-system pressure and leak behavior.
• Evaluating guidance and navigation.
• Demonstrating automated station approach and docking.
• Testing undocking and deorbit operations.
• Measuring atmospheric-entry conditions.
• Evaluating parachute deployment and airbag-assisted landing.

An uncrewed mission cannot reproduce every condition of a crewed flight. It cannot fully test astronaut workload, cabin procedures, emergency response, or crew interaction with mission control. It can, however, provide important data about the spacecraft’s physical performance.

The return sequence requires precise coordination. Starliner must separate from the station, conduct a deorbit burn, enter the atmosphere at the correct angle and speed, withstand extreme heating, deploy parachutes, and land under airbags. An uncrewed flight could provide data on propulsion, heating, structural loads, parachute behavior, landing forces, and onboard computer performance.

A successful flight would increase confidence but would not automatically approve another crewed mission. NASA would still need to review the data and determine whether additional testing or design changes were necessary.

What Must Be Investigated Before the Next Flight?

Thruster and Propulsion Performance

NASA and Boeing must determine why several reaction-control-system thrusters underperformed during the 2024 flight. Possible contributors include excessive heat, seal behavior, restricted propellant flow, hardware design, software commands, and operating procedures.

Engineers must establish whether the problem was limited to specific components or could affect other spacecraft. They must also assess redundancy. A crewed spacecraft does not need every thruster to operate perfectly, but it must retain enough capability for critical normal and emergency maneuvers.

Helium-System Concerns

Helium pressurizes Starliner’s propulsion system. Engineers must identify the source and rate of each leak, determine why it occurred, and decide whether the design requires modification. Corrective actions could include replacing components, changing seals, altering operating procedures, or redesigning parts of the system.

A leak may remain within flight limits while still revealing a design weakness that NASA wants resolved before another crewed mission.

Software, Navigation, and Operations

Starliner’s software controls guidance, navigation, propulsion commands, docking, communications, and return operations. Software changes must be tested against normal and unexpected conditions.

NASA and Boeing must also evaluate how onboard automation interacts with ground control. Crews and mission controllers need clear procedures for automatic actions, human intervention, and conflicting or incomplete data. Simulations and integrated tests can expose failures that cannot safely be reproduced in orbit.

How a Future Uncrewed Mission Could Differ

The 2024 Crew Flight Test emphasized crewed operations, station docking, life-support performance, and the complete transportation cycle. A future uncrewed mission would likely focus on corrective measures and risk reduction.

NASA could add extended thruster firings, more detailed helium monitoring, additional propulsion measurements, or a return profile designed to collect reentry and landing data. The spacecraft might carry test equipment or limited cargo rather than astronauts.

NASA can accept some risks during an uncrewed demonstration that it cannot accept during a crewed mission. However, the flight would still need to protect the International Space Station, other spacecraft, launch personnel, and recovery teams.

An uncrewed mission also cannot fully demonstrate crew workload, cabin ergonomics, astronaut interaction with flight software, human responses to alarms, or emergency actions that require astronauts. NASA could therefore require additional crewed testing or a detailed certification review afterward.

What the Decision Means for NASA and Boeing

NASA wants Starliner and Crew Dragon both available because redundancy improves resilience. Two providers can create more launch opportunities, support flexible scheduling, and reduce dependence on one spacecraft.

Crew transportation affects station research, maintenance, spacewalk planning, cargo delivery, and emergency response. NASA also coordinates station operations with Russia, Europe, Japan, Canada, commercial partners, and other organizations, so changes to one vehicle can affect the wider program.

Boeing faces financial and reputational pressure from Starliner’s delays and additional testing. More testing increases costs and extends the schedule before routine missions can begin. At the same time, thorough testing could protect the program’s future by resolving problems before another crewed flight.

Claims about cancellation, penalties, or future funding require official documentation. The confirmed issue is that Starliner remains subject to NASA’s technical and safety approval process.

What Happens Before Another Crewed Mission?

NASA and Boeing must analyze flight data, inspect returned hardware, identify the causes of the propulsion and helium-system issues, and show that proposed design changes address those causes.

Testing could include:

• Thruster hot-fire tests.
• Pressure and leak tests.
• Propulsion-system inspections.
• Software-in-the-loop simulations.
• Docking simulations.
• Reentry and landing analysis.
• Parachute testing.
• Full mission rehearsals.

Before launch, NASA conducts formal flight-readiness reviews involving program managers, engineers, mission operations teams, and safety officials. The reviews examine unresolved hazards, corrective actions, procedures, and contingency plans.

The next launch date will depend on technical evidence rather than a fixed timetable. NASA has not established a final date for another crewed Starliner mission until the spacecraft meets its requirements.

Frequently Asked Questions

Is an uncrewed Starliner flight officially approved?

NASA has indicated that additional testing and certification work are required. A proposed or studied mission should not be confused with formal launch approval.

What would an uncrewed flight test?

It could evaluate propulsion, helium-system performance, software, navigation, docking, reentry, parachutes, and landing.

Would it dock with the International Space Station?

That depends on NASA’s mission design and risk assessment. Docking would provide a stronger test of station-approach operations but would also add complexity.

Would the spacecraft carry cargo?

The payload would depend on the approved mission. A test vehicle might carry equipment or limited supplies, but an operational cargo mission should not be assumed without an official announcement.

When could Starliner carry astronauts again?

The timing depends on investigation results, corrective actions, testing, and NASA certification. No unverified date should be treated as final.

Conclusion

NASA’s consideration of an uncrewed Starliner test reflects a central lesson from the 2024 Crew Flight Test: spacecraft problems must be understood before astronauts are placed at risk.

Wilmore and Williams safely returned aboard Crew Dragon after NASA decided that Starliner should land without them. The decision extended their mission but gave engineers more time to study the spacecraft’s propulsion and helium-system behavior.

An uncrewed flight could provide valuable evidence about whether corrective actions work under real orbital and reentry conditions. It would not replace NASA’s certification process or prove that every crewed-flight risk had been eliminated.

Starliner’s future depends on transparent investigations, successful ground and flight testing, and measurable improvement. The outcome affects Boeing, NASA, International Space Station operations, and the broader goal of maintaining multiple U.S. crew transportation options.