EXPLAINER: 4 will circle Earth on 1st SpaceX private flight


              In this Sunday, Sept. 12, 2021 photo made available by SpaceX, from left, Chris Sembroski, Sian Proctor, Jared Isaacman and Hayley Arceneaux sit in the Dragon capsule at Cape Canaveral in Florida, during a dress rehearsal for the upcoming launch. The fully automated Dragon is the same kind that SpaceX uses to send astronauts to and from the International Space Station for NASA. But the chartered flight won't be going there. (SpaceX via AP)
            
              In this July 2, 2021 photo provided by John Kraus, from left, Sian Proctor, Chris Sembroski, Jared Isaacman and Hayley Arceneaux pose for a photo at Duke Health in Durham, N.C, during hypoxia training to understand how each crew member reacts in a low-oxygen environment. (John Kraus/Inspiration4 via AP)
            
              In this July 11, 2021 photo provided by John Kraus, from left, Hayley Arceneaux, Chris Sembroski, Jared Isaacman and Sian Proctor float during a zero gravity flight out of Las Vegas. The plane, a modified Boeing 727, flies multiple parabolic arcs to provide 20-30 seconds of weightlessness. (John Kraus/Inspiration4 via AP)
            
              In this July 28, 2021 photo provided by John Kraus, from left, Jared Isaacman, Sian Proctor, Hayley Arceneaux and Chris Sembroski stand in the crew access arm at Launch Complex 39A at Kennedy Space Center in Florida. They will use this arm to board the Falcon 9 rocket on launch day. (John Kraus/Inspiration4 via AP)
            
              In this Aug. 8, 2021 photo provided by John Kraus, from left, Chris Sembroski, Sian Proctor, Jared Isaacman and Hayley Arceneaux stand for a photo in Bozeman, Mont., during a "fighter jet training" weekend to familiarize the crew with G-forces. (John Kraus/Inspiration4 via AP)