Starliner

Boeing’s CST-100 Starliner is one of two spacecraft NASA ordered in September 2014 to carry astronauts to the International Space Station; Boeing’s firm fixed-price contract was worth up to $4.2 billion, against $2.6 billion for SpaceX. CST stands for Crew Space Transportation, and 100 for the Kármán line, 100 kilometers up. Once certified, Starliner is to carry up to four NASA crew members and about 220 pounds of cargo, launching on a United Launch Alliance Atlas V.

The first uncrewed Orbital Flight Test, on December 20, 2019, did not reach the station; a second uncrewed test docked there in May 2022. The Crew Flight Test launched Butch Wilmore and Suni Williams on June 5, 2024, but some thrusters did not perform as expected and the helium system leaked. NASA brought Starliner home without crew in September 2024, and the two astronauts returned with NASA’s SpaceX Crew-9 mission on March 18, 2025. NASA classified the test as a Type A mishap, its most serious category.

In November 2025 NASA cut Boeing’s firm order to four flights, with two more as options, and made the next mission, Starliner-1, uncrewed. On September 28, 2026, NASA said Starliner-1 could fly in December 2026 or January 2027, that it intends to exercise both options, that it will work to certify ULA’s Vulcan to launch Starliner after the last Atlas V, and that it plans to fly astronauts again on Starliner-2 by 2028.

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