With a roar that lit up the night sky, NASA sent its colossal next-generation rocket soaring into space for the first time on Wednesday. The Space Launch System rocket, or SLS, took off at 1:47AM ET from Cape Canaveral, Florida, signaling the start of a bold new era for the US government’s space program.

It also marks a major success for NASA’s Artemis program to return to the Moon, which has been plagued by years of delays, development mishaps, and billions of dollars in budget overruns. During the past few months, both hurricanes and technical difficulties caused launch delays — including two scrubs. Then, tonight, engineers managed to fix both an intermittent hydrogen leak and a “bad ethernet switch” in the hours just before launch.

NASA can now put many of those problems in the rearview as it looks ahead to the program’s future.

“For the Artemis generation, this is for you,” said Charlie Blackwell-Thompson, Artemis launch director, as she gave the go-ahead for launch.

The SLS carried its Orion capsule to an altitude of just under 4,000 kilometers before the two craft separated and the core stage of the rocket fell back to Earth, falling into the Pacific Ocean. (The two solid boosters, which separated even earlier, fell back into the Atlantic.) Orion will continue onward to the Moon, which it will orbit for several days before returning to Earth. The capsule is scheduled to splash down in the ocean on December 11th. For this mission, Orion is uncrewed — save for a trio of mannequins, two of which were fitted with sensors to measure radiation levels. 

One of the main goals of this flight is to test Orion’s heat shield, which will have to endure temperatures of 2,800 degrees Celsius as it enters Earth’s atmosphere. In addition, NASA will be testing radiation shielding, sensors, navigation, and communications equipment. 

The SLS launch was also a test of NASA’s most powerful rocket configuration yet, a prerequisite for future deep space missions. Artemis I, the first integrated flight of SLS and Orion, stands 322 feet — 17 feet taller than the Statue of Liberty — and weighs 5.75 million pounds. During launch and ascent, SLS will produce 8.8 million pounds of maximum thrust, 15 percent more thrust than the Saturn V rocket.

The rocket was originally intended to debut in 2017, but it has consistently been over budget and behind schedule. Government auditors accused NASA of failing to be transparent about cost overruns that have added approximately $1.8 billion to the final budget. 

But it was finally ready to launch this year. The first launch attempt on August 29th was scrubbed after Engine No. 3 failed to reach the appropriate temperature to allow for the launch — something that NASA later blamed on a potentially faulty sensor. On September 3rd, NASA made another attempt to launch the rocket but had to scrub again when a persistent hydrogen leak appeared during fueling, defying engineers’ repeated attempts to troubleshoot the issue. Once the leaks got figured out, Hurricanes Ian and Nicole delayed NASA’s launch schedule even further, to November 16th.

This time, the weather cooperated, but hydrogen was still an issue. When an “intermittent” hydrogen leak emerged, NASA sent a crew of three technicians, known as a “Red Crew,” to the launch pad itself. In the shadow of a fully fueled rocket, they had to tighten bolts that could fix the leaky valve on the mobile launcher — the massive platform that holds the giant rocket. They succeeded. Then the Space Force noticed that one of their radar systems needed for the launch wasn’t working properly. Now an ethernet switch needed to be replaced, a process that took more than an hour. Once that was fixed, it was smooth sailing for the mission.

Nearly two hours after launch, the Orion spacecraft officially entered trans-lunar orbit, kicking off the next leg of its 26-day journey. The next flight of the Artemis program, currently set for 2024, will carry a crew of astronauts around the Moon and back without landing. Then, in 2025, NASA plans to launch the first crewed Moon landing since the Apollo 17 mission in 1972. This landing will include the first woman and the first person of color to walk on the Moon.