The International Space Station has been the main site of human exploration in orbit for the past 20 years. Crews have been shuttling back and forth for missions as short as a couple of weeks or as long as a year. But the ISS can't last forever. Matt Ondler, chief technology officer and director of spacecraft development at Axiom Space, a space hardware and services company in Houston, discusses the challenges and opportunities in developing a one of a number of commercial projects vying to become humanity’s next outpost in orbit.