NASA will launch four astronauts aboard a SpaceX Dragon capsule this weekend in the company’s first regular crew rotation to the orbiting lab. The trip, three months after SpaceX completed a high-profile trial run, will open a new era in human spaceflight for NASA as commercial firms start dominating U.S. missions in low-earth orbit.

“I hope people realize this isn’t just another launch — this is something a lot bigger,” Michael Hopkins, commander of the Crew-1 mission scheduled for Saturday, said in a NASA post on Tumblr. “Hopefully it’s setting the stage, one of those first steps to getting us to the Moon and on to Mars.”

For Space Exploration Technologies and founder Elon Musk, the flight caps almost two decades of efforts to fly people as well as cargo. The Dragon and SpaceX’s Falcon 9 rocket won NASA approval for regular crewed missions this week, making them the first vehicles the U.S. has certified to carry humans since the Space Shuttle, which was retired in 2011.

The Crew-1 launch is scheduled to blast off from Cape Canaveral, Florida, at 7:49 p.m. on Saturday, with docking at the station planned eight and a half hours later. If that attempt is scrapped, a backup launch would be set for 7:27 p.m. on Sunday with docking 27 hours later due to orbital mechanics.

Beyond becoming the U.S. space agency’s first regular commercial launch, the Crew-1 mission is also the first NASA-staffed mission licensed by the Federal Aviation Administration. The regulator is assuming responsibility for public safety because the flight will be conducted by a commercial company.

NASA on Friday was checking on Musk’s recent contacts with agency personnel after he tweeted late Thursday that he might be infected with the new coronavirus. His health isn’t likely to affect the launch, NASA Administrator Jim Bridenstine said at a news conference. Astronauts self-quarantine for two weeks before liftoff.

Hopkins, 51, an Air Force colonel and test pilot, will make his second sojourn to the space station, seven years after his first. He will be joined by three others on the mission:

• Shannon Walker, 55, a physicist and Houston native, will serve her second stint on the orbiting lab.
• Victor Glover, 44, a Navy pilot from California, will be taking his first flight to space. He will be the first Black astronaut to stay on the space station for a full six-month rotation, according to NASA.
• Soichi Noguchi, 55, a Japanese astronaut and aeronautical engineer, has the most space experience among the crew and will become one of the very few people to leave the Earth on three vehicles: Russia’s Soyuz, the retired NASA Space Shuttle and the SpaceX Dragon.

The four astronauts will push the space station to maximum occupancy when they join the three people already there. That will require changes in how mission controllers schedule the daily exercise regimen for each crew member. There will also be a squeeze on personal quarters where the astronauts sleep and have time to themselves.

The space station currently has a half-dozen crew berths, and NASA is completing work on a seventh. In the meantime, Hopkins will sleep aboard the Dragon capsule.

If that doesn’t work out, a crew member could “camp out” in one of the space station’s modules, David Wiedmeyer, a training officer at Johnson Space Center, wrote Nov. 12 in a Reddit “Ask Me Anything” session about the mission.

The National Aeronautics and Space Administration began its commercial crew program in 2010 to field a replacement for the shuttle. NASA selected SpaceX and Boeing Co. in September 2014. Boeing, which suffered delays in its work following a botched December 2019 test flight, plans a second trial without crew in the first quarter of next year.

SpaceX completed its test-flight program Aug. 2 when astronauts Bob Behnken and Doug Hurley returned from a two-month stay aboard the station.

Since then, the company has bolstered parts of the Dragon’s heat shield, made adjustments so that the landing parachutes deploy at a slightly higher altitude and reinforced some areas of the capsule so it can withstand rougher seas.

Three months ago, when Behnken and Hurley splashed down south of Pensacola, Florida, recreational boaters approached the spacecraft. When the crew of the latest mission returns in the spring of 2021, NASA has already announced one major change for the landing site: A larger flotilla of Coast Guard ships to keep pleasure craft away.