In September 2014 Boeing was one of two companies selected by NASA to develop crewed spacecraft to ferry astronauts to the International Space Station, the other being SpaceX.

The flight ended in partial failure, with Calypso being forced to return to Earth without arriving at the ISS due to an issue with the spacecraft's onboard Mission Elapsed Timer (MET) clock software.

[2] Prior to OFT, Spacecraft 2 was scheduled to fly on Boe-CFT, the first crewed Starliner flight test sometime in 2020, although the partial failure that occurred on Boe-OFT threw this into doubt.

[4] Due to unexpected valve position indications in the Starliner propulsion system, the launch was further delayed to later in August while engineering teams investigated the problem.

During the pre-launch readiness check on the pad, sensors indicated that 13 of the NTO valves had failed to open on command.

On 13 August 2021, Boeing decided to return the spacecraft to the Commercial Crew and Cargo Processing Facility in order to perform a deeper-level troubleshooting of the valves.

[6][7] After inspection it was found that the valves had been corroded by intrusion of moisture from the humid Florida air, which reacted with dinitrogen tetroxide, creating nitric acid, which then reacted with aluminum parts inside valves, creating corrosive products, mostly aluminum nitrate.

Spacecraft 2 launched on a rescheduled OFT-2 mission from the Cape Canaveral Space Force Station on an approximately week-long test flight to the ISS.