BALTIMORE — NASA announced Aug. 3 the assignment of eight agency astronauts, a mix of veterans and rookies, as well as one company astronaut to fly on the first set of commercial crew missions by Boeing and SpaceX.

In a ceremony at the Johnson Space Center in Houston, NASA announced who would fly on the crewed test flights planned for next year of Boeing’s CST-100 Starliner and SpaceX’s Crew Dragon, as well as the first post-certification, or operational, missions by each vehicle.

“For the first time since 2011, we are on the brink of launching American astronauts on American rockets from American soil,” said NASA Administrator Jim Bridenstine at the event attended by several members of Congress and other NASA and industry officials.

The SpaceX crewed test flight, currently scheduled for April 2019, will be flown by NASA astronauts Robert Behnken and Douglas Hurley. Each astronaut flew on two shuttle missions, including Hurley on the final shuttle flight, STS-135, in 2011. They were two of the four astronauts selected by NASA in July 2015 to be trained to fly commercial crew missions.

The Boeing crewed test flight, planned for mid-2019, will carry three people, including former NASA astronaut Chris Ferguson, commander of STS-135 and, for the last several years, a Boeing employee working on the Starliner program. He will be joined by Eric Boe, who flew on two shuttle missions and was another astronaut selected for commercial crew training in 2015, and Nicole Aunapu Mann, a member of the astronaut class of 2013 who will be making her first flight.

NASA officials didn’t state why a three-person crew would be flying on the Starliner test flight, but the agency announced an agreement earlier this year with Boeing to study turning that crewed test flight into an operational mission in the event of further commercial crew delays. That would include adding a third astronaut to the mission and extending its stay on the station from two weeks to up to six months.

The first Starliner post-certification mission, yet to be formally scheduled, will fly NASA astronauts Josh Cassada and Sunita Williams. Cassada is a rookie astronaut selected in 2013, while Williams, the fourth astronaut selected for commercial crew training, has spent 322 days in space on two long-duration station missions. The first Crew Dragon post-certification mission will be flown by Victor Glover, another rookie astronaut selected in 2013, and Mike Hopkins, who spent 166 days on one station mission.

Both Crew Dragon and Starliner are designed to carry four astronauts. In a statement, the agency said that additional crew members for those first post-certification missions “will be assigned by NASA’s international partners at a later date.” That will include Canada, Europe and Japan, who have traditionally relied on NASA for ISS transportation. It may also include Russia, as NASA officials have discussed in the past flying Russian cosmonauts on commercial crew vehicles, possibly in exchange for seats on Russian Soyuz spacecraft.

The crew assignments came a day after NASA issued new schedules for the uncrewed and crewed test flights, pushing back the flights by several months from earlier schedules. However, at the announcement companies sounded more confident in those revised schedules.

“Predicting launch dates can make a liar out of every one of us,” acknowledged Gwynne Shotwell, president of SpaceX. “We had our quarterly [review] this week, and for the first time in years, it felt real. It’s real. It’s right here.”

After announcing the crews, Bridenstine engaged in a largely lighthearted question-and-answer session with the selected astronauts, who expressed their delight in being selected and anticipation in flying on these next-generation vehicles.

“It is absolutely like flying the iPhone,” said Behnken in response to a question from Bridenstine. “I look forward, sir, to getting you down there at some point out in Hawthorne [SpaceX’s California headquarters] and maybe you can sit next to us in the cockpit and go through flying the iPhone to dock to space station.”

“So, just to be clear, Bob, I’ve already done that, and I nailed it,” responded Bridenstine, a former naval aviator.

“I think I probably did it better,” Behnken said.