NASA astronauts, from left, Bob Behnken and Doug Hurley, assigned to fly on SpaceX's Demo-2 test flight of its Crew Dragon, are inside a mockup of the spacecraft at NASA's Johnson Space Center in Houston on Aug. 2, 2018, ahead of the agency's announcement of their commercial crew assignment Aug. 3. Nine U.S. astronauts were selected for commercial crew flight assignments on the first test flights and operational missions for SpaceX's Crew Dragon and Boeing's CST-100 Starliner.