As an alternative, NASA contracted with private companies such as SpaceX for the Commercial Crew Program, which is expected to cost 50% less than Soyuz once in regular operation.

[22] NASA astronaut Kjell Lindgren was the sole backup crew member for the flight, backing up both Hurley and Behnken for the mission.

[23] The mission insignia was designed by artist Andrew Nyberg from Brainerd, Minnesota, a nephew of spacecraft commander Hurley.

[27][28] The SpaceX patch shows the top of the company's spacesuit, with the ISS and North America portrayed on the helmet shield and a white star denoting the launch site at Cape Canaveral.

NASA calculated the loss-of-crew (LOC) probability for the test flight as 1-in-276, better than the commercial crew program requirement threshold of 1-in-270.

The 1-in-276 number included mitigations to reduce the risk, such as on-orbit inspections of the Crew Dragon spacecraft once it was docked to the space station to look for damage from micrometeoroids and orbital debris (MMOD).

[31][32] SpaceX traced the cause of the anomaly to a component that leaked oxidizer into the high-pressure helium lines, which then solidified and damaged a valve.

[34] NASA Administrator Jim Bridenstine said on 9 April 2020 that he was "fairly confident" that astronauts could fly to the ISS aboard SpaceX's Crew Dragon spaceship at the end of May or in early June 2020, pending final parachute tests, data reviews and a training schedule that could escape major impacts from the ongoing COVID-19 pandemic.

Bob Behnken and Doug Hurley will have performed duties and conducted experiments as crew on board the ISS for several months.

Hurley and Behnken were expected to live and work aboard the space station for two or three months, and then return to Earth for a splashdown in the Atlantic Ocean east of Cape Canaveral.

[55] Hurley and Behnken described Falcon 9 as a "very pure flying machine", and the ride on SpaceX Merlin engines as much smoother than with Space Shuttle Solid Rocket Boosters.

Hurley demonstrated the ability to pilot the spacecraft via its touchscreen controls until it reached a distance of 220 metres (720 ft), after which Endeavour autonomously soft-docked to the pressurized mating adapter PMA-2 on the Harmony module of the ISS at 14:16 UTC on 31 May 2020.

[5] Approximately two hours after docking, the last of three hatches between Endeavour and ISS was opened, and Hurley and Behnken boarded the ISS at 17:22 UTC, welcomed by and joining the Expedition 63 crew, consisting of NASA astronaut and station commander Chris Cassidy and Russian cosmonauts Anatoly Ivanishin and Ivan Vagner.

[6][66][67][68] Over their time aboard the ISS, Hurley and Behnken spent over 100 hours completing science experiments, while traveling 27 million miles over their 1024 orbits of the Earth.

[69] NASA mission managers had evaluated additional sites off Panama City, Florida, Tallahassee, Tampa, and Daytona Beach to provide more options in the event of stormy tropical weather.

[3] The United States Coast Guard advised against entering a 10 nmi (19 km; 12 mi) square defined in its Notices to Mariners for the hours leading up to splashdown noting "hazardous space operations" and the Federal Aviation Administration (FAA) restricted air traffic in the area in a NOTAM.

While crews worked, many private boats entered the hazardous area defined by the Coast Guard despite earlier warnings.

The United States Coast Guard said in a statement later that evening that previous warnings were advisory in nature; the three patrol boats in the area were stationed within their jurisdiction and did not provide sufficient resources to board vessels interfering with the recovery.

[70][73] Later SpaceX and NASA confirmed that their next mission will have a 16 km (9.9 mi) enforceable keep-out zone patrolled by the U.S. Coast Guard.

The "nest" was then pulled further on board the ship where a 30-minute purge of the service section took place, as there were abnormally high levels of dinitrogen tetroxide detected around the capsule.

[17][82] Hurley and Behnken were then greeted by crew aboard GO Navigator and were subsequently helped out of the capsule and onto stretchers where they were taken into the onboard medical facility, before taking a helicopter back to land.

[73] Post-flight analysis of the Dragon's heat shield revealed higher-than-expected erosion at four points where the capsule bolts to the trunk of the vehicle using tension ties.