Overview
The CST-100 Starliner is a crew capsule developed by Boeing under NASA's Commercial Crew Programme (CCP), alongside SpaceX's Crew Dragon. Starliner is designed to carry up to 7 astronauts to the International Space Station, launching atop a ULA Atlas V rocket (and eventually Vulcan Centaur). However, Starliner's development has been marked by significant delays, software errors and thruster issues that have made it one of the most troubled spacecraft programmes in modern spaceflight.
Key Specifications
| Parameter | Value |
|---|---|
| Manufacturer | Boeing |
| Crew Capacity | Up to 7 (4 for NASA missions) |
| Diameter | 4.56 m (15 ft) |
| Height | 5.03 m (capsule + service module) |
| Mass | ~13,000 kg |
| Habitable Volume | 11 m³ |
| Launch Vehicle | Atlas V N22 / Vulcan Centaur |
| Landing | Airbag-assisted land landing (western US) |
| Abort System | 4 × Launch Abort Engines (pusher configuration) |
| Reusability | Capsule designed for 10 flights |
Development History
OFT-1 (December 2019): The first uncrewed Orbital Flight Test failed to reach the ISS due to a mission elapsed timer software error that caused excessive thruster firings. A second critical software bug was discovered during the mission that could have caused a catastrophic collision between the capsule and service module during separation. The capsule returned safely but never reached the station.
OFT-2 (May 2022): The second uncrewed test reached the ISS successfully, but experienced thruster anomalies during approach and docking. Two of the capsule's orbital manoeuvring thrusters failed during flight.
CFT (Crew Flight Test, June 2024): The first crewed flight carried NASA astronauts Butch Wilmore and Suni Williams to the ISS. During approach, five of Starliner's 28 reaction control thrusters failed, and helium leaks were detected in the propulsion system. NASA ultimately decided the thruster issues posed too much risk for crew return. Wilmore and Williams remained on the ISS, and Starliner returned to Earth uncrewed in September 2024. The astronauts returned months later aboard a SpaceX Crew Dragon.
Land Landing
Unlike Dragon (which splashes down in the ocean), Starliner is designed for land landings using airbags deployed beneath the heat shield. This approach aims to reduce recovery costs and simplify capsule refurbishment for reuse. Landing sites are planned in the western United States (White Sands, New Mexico being the primary site).
Programme Status
Following the CFT thruster and helium leak issues, the future of the Starliner programme is uncertain. Boeing has absorbed over $1.6 billion in cost overruns on the fixed-price CCP contract. NASA has expressed continued interest in maintaining two crew transport providers for redundancy, but operational Starliner crew rotation missions depend on resolving the propulsion system issues definitively.