NASA stops launch rehearsal for its giant Moon rocket

NASA on Sunday morning cut short a practice countdown for its new megarocket, the Space Launch System. It is a key component of upcoming missions to return astronauts to the moon, and the agency said there was a problem with the mobile launch tower.

NASA will try again on Monday.

The 322-foot-tall rocket and its Orion capsule are crucial components for Artemis, NASA’s moon landing program. The system, which can launch astronauts to lunar orbit but will rely on other components to land them on the moon’s surface, is billions of dollars over budget and years behind schedule.

The weekend’s exercise, which NASA calls a wet dress rehearsal, is the last major test before the rocket launch is launched on its first uncrewed test flight, which could occur as soon as this summer. By simulating a countdown without the excitement of engines igniting and a rocket rising to space, NASA hoped to work out glitches with equipment and procedures.

The rehearsal, which started Friday night, was “wet,” because it was to include pumping more than 700,000 gallons of liquid oxygen and liquid hydrogen into the massive rocket’s propellant tanks.

On Saturday afternoon, severe thunderstorms passed over the launch site, with four lightning bolts striking protective towers around the rocket and launcher. Preparation work at the launcher had to be paused during the storm, but after reviewing the data, NASA said there was no damage and the countdown could continue.

On Sunday, the dress rehearsal was more than three hours behind schedule. Then the halt occurred just before the propellants were to begin flowing. NASA said the problem was found in the mobile launcher, or the movable tower with numerous systems used to manage the rocket on the ground before it lifts off. Fans that create positive air pressure in enclosed areas on the mobile launcher were not working. The positive pressure is needed to prevent buildup of hazardous gases including ones that could potentially ignite.

Then a backup fan also failed, apparently for a different reason, leading to the halt in the countdown.

This article originally appeared in The New York Times.

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