Mike Blake / Reuters

CAPE CANAVERAL, Fla.—The stars were out over the marshlands near the launchpad. Crickets trilled a steady melody, interrupted by the occasional squawk of a bird flying low over the water. Except for a few pops of lightning, the sky was a very deep blue, almost black. It was, by all appearances, nighttime.

Then came a burst of blinding light.

A SpaceX rocket ignited its engines just before 3 a.m. ET on Saturday and rose like a ball of fire against the sky. A gold-colored glow spread across the horizon, like a racing sunrise in the middle of the night.

For the first time, a commercially built spacecraft designed to carry humans has launched to the International Space Station.

There are no people on board, but the hope is that the next such flight will carry a crew. The United States hasn’t sent people to space from American soil since the Space Shuttle program ended in 2011 after three decades of operation. To reach the International Space Station, where they live and work for six months at a time, NASA astronauts travel to Kazakhstan and launch inside a Russian capsule, atop a Russian rocket, snuggled close to Russian cosmonauts. To break its reliance on this arrangement, which costs more than $80 million per seat, NASA hired SpaceX, along with the aerospace company Boeing, to develop a crew-transportation system.

The successful launch of SpaceX’s Dragon spacecraft on Saturday is a meaningful milestone for NASA. An expensive arrangement with a diplomatic rival is not ideal. If the rest of the spacecraft’s journey goes well, NASA astronauts could fly on Dragon in time for the 50th anniversary of the Apollo moon landing in July.

It’s a significant achievement for SpaceX too. Returning human spaceflight to American shores would boost the company’s prestige, and on top of that, SpaceX managed to edge out Boeing. Both companies have experienced schedule delays and technical issues, but SpaceX has gained a decisive lead.

Jim Bridenstine, the NASA administrator, said that he is “100 percent confident” a crewed mission will launch this year.

Elon Musk, the SpaceX founder, is optimistic too. “So far, it’s looking quite promising,” Musk said.

The Dragon spacecraft is now in orbit, but the mission is far from over. The spacecraft must fire its engines to lift itself higher and move toward the ISS. As it approaches the station, Dragon will prepare for a maneuver that it has never attempted.

SpaceX has flown a different version of the Dragon spacecraft, designed to carry only cargo, to the ISS. These capsules were captured by a powerful robotic arm attached to the station and operated by an astronaut inside. This time, the Dragon spacecraft will rely on its autonomous-navigation systems to dock to a port.

This attempt may be more nerve-racking than the launch itself. SpaceX has mastered rocket launches and booster landings—the booster on this flight returned to Earth and gently touched down on a ship off the coast of Florida, a feat SpaceX perfected only a few years ago. But it has never tried to attach a spacecraft to a space station traveling 17,500 miles per hour. Russia’s space agency, Roscosmos, which operates half of the ISS, was even hesitant to formally approve the plan.

If SpaceX sticks the docking, the crew of the ISS—an American, a Russian, and a Canadian—will be able to enter the Dragon spacecraft and welcome its contents: 400 pounds of cargo, and a mannequin in a spacesuit that SpaceX has named Ripley, for the protagonist of the Alien films, portrayed by Sigourney Weaver. After five days, Dragon will detach, reenter Earth’s atmosphere, and parachute down to the Atlantic Ocean, where SpaceX recovery crews will be waiting.

More tests of the system’s soundness will follow after Dragon returns. If everything checks out, the next spacecraft will carry two NASA astronauts, Doug Hurley and Bob Behnken, both alumni of the Space Shuttle program. Hurley and Behnken watched the launch unfold alongside Musk and engineers at Kennedy Space Center, inside the room where mission control once gathered for the launches of space shuttles. Hurley, a veteran pilot who tested aircraft in the Marines before he joined NASA, told reporters, “I can’t begin to explain to you how exciting it is for a test pilot to be on the first flight of a vehicle.”

NASA says SpaceX must resolve some technical concerns before the agency is ready to replace the mannequin with astronauts. But its first passengers say they feel ready, and they’re not nervous.

“Part of the reason that we’re in the job that we’re in is that we tend to get nervous kind of after the fact rather than in the moment,” Behnken said. “They do their best, from a training perspective, to try to beat that all out of you by giving you a lot of experiences before you jump into the actual spaceship and ride it into space.”

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