The launch marks the first time a privately owned and operated spacecraft received certification from NASA for human spaceflight Credit: AP They will join NASA astronaut Kate Rubins and Russia's Sergey Ryzhikov and Sergey Kud-Sverchkov, who are already onboard the ISS. NASA and SpaceX have been working for a decade to return human spaceflight to the United States while ensuring the multibillion-dollar ISS remains functional and staffed. A safe docking marks the end of the first step in NASA's and SpaceX's landmark mission, and marks the first fully operational crewed mission for SpaceX. The Dragon capsule, named Resilience, is the first privately owned and operated spacecraft to receive certification from NASA for human spaceflight. SpaceX received the important certification just days ago. With just three staffers - a drop from 13 astronauts in 2009 - the ISS has fewer people to run experiments and keep the station maintained. Glover, a rookie astronaut and Navy commander, would be the first Black astronaut to spend an extended period aboard the ISS Credit: AFP via Getty Images