The NASA astronauts going back to the Moon this decade will be riding the Orion spacecraft – the motor of which has just passed an important safety test. The launch abort system (LAS) has been tested for the first and final time.

The LAS is critical to safeguarding the astronauts. If something goes wrong during launch, the system is designed to move out of the way of the rocket below it, the space launch system (SLS). On February 25, NASA tested the attitude control motor, built by the Northrop Grumman, which allows the capsule to steer during an abort. Thanks to this successful test, the motor qualifies for human missions.

The LAS has three solid rocket engines. The abort motor pulls the crew module away from the SLS. The attitude control motor steers the capsule, and finally, a jettison motor pushes the LAS away before parachutes are deployed. With the test this week, all these motors have now been triple-tested.

The tests have been a decade in the making, with smaller and larger scenarios tested over the year. While this was a static test, there have been several showing exactly what might happen during an emergency at launch or a few minutes afterward.

The space agency ran a test in 2010 that showed if there was a problem on the launchpad, the Orion module was able to work it out and initiate the LAS. Last year, a booster rocket sent the spacecraft up 9.45 kilometers (5.87 miles), where it performed the abort procedure during a critical time in a real launch. At that altitude, the spacecraft would be experiencing incredible aerodynamical forces.

The goal is for the first crew to launch on Orion as part of the Artemis II mission. This will take place by 2023 and will include an insertion into lunar orbit, something not done with a crew since the last Apollo mission in the 1970s. NASA believes that humans will be back on lunar soil by 2024 and certainly by the end of the decade at the latest.