Artemis 1: Why Nasa scrubbed Monday’s Moon rocket launch and what’s next

Nasa engineers are assessing engine and thermal insulation issues that forced the space agency to scrub the launch of its new Moon rocket on Monday

The launch of Nasa’s new massive Moon rocket scheduled for Monday morning has been scrubbed due to a problem with one of the rocket’s engines, but the space agency can try again as soon as 2 September.

The two-hour launch window for Nasa’s Artemis I mission opened at 8.33am Monday morning, and Nasa’s ground operations crew had begun filling the massive Space Launch System (SLS) rocket at 1.14am as it sat on the launch pad at Kennedy Space Center in Florida. Nasa started the launch countdown on Saturday 27 August, but the count entered a protracted hold before the launch window opened due to the engine issue.

The problem, according to Nasa updates, began as controllers began the engine bleed test, which involves allowing some of the SLS rocket’s cryogenic propellant to flow into the main engines to chill them down enough to handle the flows of liquid oxygen and liquid hydrogen necessary for launch.

“Engine 3 is not properly being conditioned through the bleed process, and engineers are troubleshooting,” Nasa officials wrote in a blog post at 6.23am Monday morning.

By 8.36am EDT, Nasa officially scrubbed the launch due to the engine bleed issue.

“We don’t launch until it’s right,” Nasa administrator Bill Nelson said in a statement about the decision to scrub the launch. “It’s just illustrative that this is a very complicated machine, a very complicated system, and all those things have to work. You don’t want to light the candle until it’s ready to go.”

The engine bleed test is one of the procedures Nasa had planned to check during a “wet dress rehearsal” for launch where the space agency rolled the SLS to the launch pad and practiced filling it with fuel and running a simulated countdown. But after four attempts to complete all aspects of the wet dress rehearsal failed, Nasa decided to move on without completing every aspect of the test in June.

Anticipating the possibility of unpredictable problems scrubbing the first launch, Nasa already has two backup launch windows in mind for a follow up launch attempt. The first backup launch window opens at 12.48pm EDT on Friday 2 September, and the second backup launch window opens at 5.12pm EDT.

Nasa has yet to announce on which, if either, of the backup launch dates the space agency will try again to launch Artemis I, as engineers are still assessing the engine bleed issue, as well as some cracks that appeared in the insulation lining the exterior of the SLS rocket’s core stage.

Artemis I, when it flies, will be the first test flight for the new SLS rocket and an important test for the Orion spacecraft it carries. Together, the launch vehicle and spacecraft are the cornerstones of Nasa’s new Artemis Moon program, which aims to land humans on the Moon again by 2025 with the Artemis III mission.

Artemis II, a crewed lunar flyby, is scheduled for May 2024, and the Artemis I mission is an uncrewed test run for a mission like Artemis II. When it launches, be it 2 or 5 September, or another date, Artemis I will power Orion on a lunar flyby mission that will last 42 days and allow Nasa to collect important data on how the rocket and spacecraft perform before the first humans board the new vehicles.

The plan, assuming that Artemis I, and then Artemis II and III, fly as expected, is for Nasa astronauts to build space stations on and around the Moon, and to spend extended time on the lunar surface over the next decade in preparation for a crewed mission to Mars in the 2040s.