NASA’s Space Launch System (SLS) rocket and Orion spacecraft launched from Kennedy Space Center in Cape Canaveral, Florida, at 6:35 p.m. ET on Wednesday, carrying a crew of four astronauts to low-Earth orbit. In about 25 hours, Orion will set course toward the Moon.

At T-0, the SLS boosters ignited in an explosion of fire, generating a whopping 8.8 million pounds of thrust to propel the Orion spacecraft skyward. The SLS lifted off about 11 minutes into the 2-hour launch window, which opened at 6:24 p.m. Shortly after ignition, the rocket cleared the launch tower, surpassed supersonic speed, and jettisoned its solid rocket boosters.

At 6:43 p.m., the rocket’s core stage separated, placing the Orion spacecraft and the upper stage (also known as the interim cryogenic propulsion stage) into LEO. About 16 minutes later, Orion’s solar array wings unfurled, completing a key configuration step. These arrays supply power to all of Orion’s systems, from propulsion to life support.

This achievement was a long time coming. It’s been 54 years since the last Apollo mission returned to Earth, and humans have not left low-Earth orbit since. Over the next nine days, the Artemis 2 astronauts will venture deeper into space than the Apollo missions ever did, swinging around the far side of the Moon and back to Earth.

The Artemis 2 launch also follows multiple delays. NASA had hoped to launch during the February window, but the SLS experienced hydrogen leaks during the wet dress rehearsal that derailed those plans. Then the March window went, well, out the window when NASA had to roll the SLS back to the Vehicle Assembly Building to repair a helium flow issue.

Today, tanking both the core and upper stages of the rocket went remarkably smoothly, with no major leaks or issues. Now that Orion is finally in space, humanity is poised to return to the Moon. If everything goes as planned over the next several hours, the ICPS will perform burns to boost the spacecraft’s orbit in preparation for the translunar injection.

Approximately 3 hours and 30 minutes after launch, Orion will separate from the ICPS, and the upper stage will begin a proximity operations demonstration to test its ability to maneuver and operate safely in close proximity to Orion. Once that’s complete, the ICPS will reenter Earth’s atmosphere and splash down in the Pacific Ocean. Orion will perform a burn to adjust its orbit, and that will conclude the first day of flight.

10 days of history in the making

Assuming the mission proceeds as planned, Orion will perform the critical translunar injection burn about 25 hours after launch. This will set the spacecraft on the path to the Moon.

Orion should enter the lunar sphere of influence on the fifth day of flight. At that point, the pull of the Moon’s gravity will be stronger than Earth’s, helping the spacecraft make a fuel-efficient lunar flyby. Orion will swing around the far side of the Moon, giving the Artemis 2 astronauts a full day to observe the surface. They will see parts of the far side never before seen with the naked eye.

NASA expects Orion to exit the lunar sphere of influence and enter a return trajectory on the seventh day of flight. The spacecraft will perform a couple more burns to adjust its trajectory on the ninth and tenth days of flight before the crew capsule separates from the service module. The crew capsule will reenter Earth’s atmosphere at speeds reaching 25,000 miles per hour (40,000 kilometers per hour) and splash down off the coast of San Diego, California.

Gizmodo will be following the mission every step of the way, bringing you the latest updates as humanity makes its epic return to lunar space. Watch this space for news on all things Artemis 2.