VIDEO: First NTSB briefing on Virgin Galactic accident

NASA astronauts Bob Behnken and Doug Hurley completed their final training sessions in Houston this week before their scheduled May 27 liftoff on a SpaceX Dragon spacecraft from the Kennedy Space Center, the first launch of humans from the Florida spaceport since 2011.

NASA officials released a nearly five-year, $28 billion plan Monday to return astronauts to the surface of the moon before the end of 2024, but the agency’s administrator said the “aggressive” timeline set by the Trump administration last year hinges on Congress approving $3.2 billion in the next few months to kick-start development of new human-rated lunar landers.

Christopher Ferguson, commander of the final space shuttle flight and now a Boeing executive, has stepped down as commander of the first piloted test flight of the company’s troubled CST-100 Starliner commercial spacecraft, he and Boeing announced Wednesday. He has been replaced by NASA astronaut Barry “Butch” Wilmore.