Elon Musk’s rocket company SpaceX launched four astronauts on a flight to the International Space Station, NASA’s first full-fledged mission sending a crew into orbit aboard a privately owned spacecraft. SpaceX’s newly designed Crew Dragon capsule, which the crew has dubbed Resilience, lifted off atop a SpaceX Falcon 9 rocket from NASA’s Kennedy Space Center in Cape Canaveral, Florida. “That was one heck of a ride,” astronaut Mike Hopkins said from Crew Dragon to SpaceX mission control about an hour after liftoff. “There was a lot of smiles.” Crew Dragon will gradually raise its orbit for the next 27 hours through a series of onboard thruster firings, aiming to dock at the International Space Station. An air leak caused an unexpected drop in capsule pressure less than two hours before launch, NASA officials said. Technicians said they conducted a successful leak check and the scheduled launch was still on. The 27-hour ride to the space station, an orbiting laboratory some 250 miles (400 km) above Earth, was originally scheduled to begin on Saturday. The launch was postponed for a day due to forecasts of gusty winds from tropical storm Eta that would have made a return landing for the Falcon 9’s reusable booster stage difficult, NASA officials said. Despite reaching this important milestone, some NASA officials are hesitant to describe the Crew Dragon as fully operational just yet. The losses of two Space Shuttles — Challenger and Columbia — still weigh on the agency, and NASA engineers don’t want to get into the mindset that their work is finished. “I think what makes us nervous at NASA is that we don’t want to ever just declare victory and say we were done learning and get complacent,” Phil McAlister, director of commercial spaceflight at NASA, said during a press briefing with reporters ahead of the flight. “I think there’s a feeling that if we start just referring to these as operational that we won’t stay hungry — we won’t remain vigilant.” SpaceX founder Elon Musk was unable the attend the launch after he tweeted that he “most likely” had a moderate case of COVID-19. NASA policy at the Kennedy Space Center requires anyone testing positive to self-isolate. The spacy agency continued with its safety precautions put in place in May. All astronauts went into quarantine along with their families in October. The launch personnel at Kennedy were required to wear face masks and the number of guests was limited.