Boeing Starliner Spacecraft 2

Boeing Starliner Spacecraft 2 is the first of two active Boeing CST-100 Starliner spacecraft developed and built under NASA's Commercial Crew Program. It was first meant to make its maiden flight on the crewed Boe-CFT, but after the partial failure of Calypso on the first Orbital Flight Test it was reassigned to the repeat uncrewed test, Boe-OFT-2, and to Starliner-1. A launch attempt on 30 July 2021 was stopped when thruster anomalies followed the docking of the Nauka module at the space station, and later attempts were halted when 13 of 24 oxidant valves in the propulsion system failed to open. Investigation found that moisture from humid Florida air had reacted with nitrogen tetroxide to form nitric acid and corrode aluminium parts in the valves. Boeing swapped in the service module meant for the crewed flight and added a nitrogen drying and valve cycling system before the spacecraft flew the rescheduled OFT-2.