Since the space shuttle made its last outing in 2011, NASA has relied on Russia’s Soyuz capsules, and more recently SpaceX’s Crew Dragon spacecraft, to carry its astronauts into space. And the manned missions were fairly unambitious, usually just ferrying crew to and from the International Space Station. But this Wednesday the agency took a major step toward revitalizing the human spaceflight program. At 1:47 am eastern time, NASA’s Space Launch System (SLS) successfully launched from Cape Canaveral, Florida for the first time carrying an unmanned Orion spacecraft that will eventually carry humans back to the moon and Mars later this century. “It took a lot to get here, but Orion is now on its way to the moon,” Jim Free, NASA’s deputy associate administrator for the Exploration Systems Development Mission Directorate, said in a news release. “This successful launch means that NASA and our partners are on a path of space exploration further than ever before for the benefit of humanity.” The launch has been a long time coming. SLS — the most powerful rocket ever built — was originally supposed to be ready by 2017, but has experienced years of delays and billions of dollars in budget overruns. Even after launch, the system suffered repeated failures, with launch attempts on August 29 and September 4 aborted due to a faulty temperature sensor and liquid hydrogen leakage, respectively. Wednesday’s launch also had to deal with some last-minute obstacles, with crews having to fix a leaking valve and a faulty ethernet switch in the hours before liftoff. In the end, everything went according to plan, with the SLS successfully lifting the Orion capsule to an altitude of about 2,500 miles before it separated and fell back to Earth. The unmanned spacecraft will now travel 40,000 miles past the Moon and then return to Earth over the next 25 days, giving NASA a chance to assess the performance of its systems before it needs to carry astronauts. One of the most critical tests will be to see how the vehicle’s heat shield withstands temperatures of up to 5,000 degrees Fahrenheit as it re-enters Earth’s atmosphere. It will also carry several mannequins loaded with sensors designed to measure the forces and radiation that human astronauts will be exposed to while on board. Assuming all goes according to plan, the mission will lay the groundwork for Artemis II, which will carry a human crew around the moon without landing in 2024, according to current schedules. It will be followed in 2025 by Artemis III, which will land the first woman and the first person of color on the moon. However, this third mission will rely on more than just NASA. The space agency has contracted SpaceX to build a modified version of the Starship spacecraft it is currently developing to serve as a lander. A crew of four astronauts will fly to the moon in Orion, but two will then be transferred to the so-called “Human Landing System” in orbit before descending to the surface. By then, NASA also hopes to have a small space station called the Lunar Gateway in orbit around the moon. The plan is for both spacecraft to dock with the station during the crew transfer, although it is also possible for both to dock directly in case the Gateway is not ready in time. Either way, the station is likely to play an important role for future missions, as a stopover for astronauts heading to the lunar surface and eventually as a staging post for trips to Mars. Questions remain over whether NASA can actually achieve its ambitious goals for a return to the moon, with its watchdog recently telling lawmakers that development delays in key systems mean Artemis III will not launch until 2026 at the earliest .And missions to Mars aren’t likely to be in the cards until at least the late 2030s, according to NASA Administrator Bill Nelson. However, the launch of Artemis I is a major milestone in space exploration and marks the beginning of an exciting new era of human spaceflight that could eventually take us further into the solar system than we’ve ever gone before. Image credit: NASA