SpaceX is set to launch its first astronaut crew into orbit Wednesday afternoon, marking the return of human spaceflight from U.S. soil after nearly a decade.

The countdown to launch is underway. Astronauts Bob Behnken and Doug Hurley are scheduled to lift off aboard SpaceX's Crew Dragon capsule from Florida’s Kennedy Space Center at 4:33 p.m. ET on a test flight to the International Space Station. The historic launch will be the first time that NASA astronauts have flown to the orbiting lab in a commercially built spacecraft.

Read more and watch the launch on NBCNews.com, NBC News NOW and MSNBC.