Hayley Arceneaux is an American physician assistant and commercial astronaut. She joined billionaire Jared Isaacman on SpaceX's first private spaceflight Inspiration4, which launched on September 16, 2021, 00:02:56 UTC, and successfully water-landed local-time on Saturday, September 18. Arceneaux became the first human in space with a prosthetic leg bone after surviving bone cancer. At age 29, Arceneaux was the youngest American to travel to space, surpassed a few months later by 23-year-old Cameron Bess aboard Blue Origin NS-19. As Bess' flight was suborbital, Arceneaux remained the youngest American to have orbited Earth.