NASA Stops Launch Rehearsal for Its Giant Moon Rocket

The Space Launch System was cut short on Sunday morning. The agency said there was a problem with the mobile launch tower, which is a key component of upcoming missions to return astronauts to the moon.

NASA will try again on Monday.

NASA's moon landing program relies on the 322-foot-tall rocket and its capsule. 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 last major test before the rocket is launched on its first uncrewed test flight, which could occur as soon as this summer, is the weekend's wet dress rehearsal. NASA wanted to work out problems with equipment and procedures by doing a simulation without the excitement of engines and a rocket rising to space.

The rehearsal was to include pumping more than one million gallons of liquid oxygen and liquid hydrogen into the massive rocket's propellant tanks.

There were four lightning bolts that struck protective towers around the launch site on Saturday. After reviewing the data, NASA said there was no damage and the launch could continue.

The dress rehearsal was three hours late. Just before the propellants were to start flowing, the halt occurred. NASA said the problem was found in the mobile launcher, a tower with many systems used to manage the rocket on the ground before it lifts off. Positive air pressure was not being created by fans on the mobile launcher. The positive pressure is needed to prevent the build up of hazardous gases.

During a news conference Sunday evening, the launch director said that the fan has been running since the mobile launcher was moved to the launch site.

The fan is used to blow in more air for loading propellants. The fan ran in this mode for a long time.

We don't believe that was related to the lightning.

A backup fan also failed, which led to the halt in the count.

We decided to stay down because it was the first time we had loaded a vehicle.

The loading of propellants is to start at 7 a.m. on Monday. The exercise ends in the afternoon. There is a chance that another attempt could be made on Tuesday.

The first test flight of the Space Launch System, Artemis 1, could occur this summer with the capsule traveling around the moon and back to Earth without astronauts on board. The second Artemis flight would have astronauts on board. The first lunar landing by astronauts since 1972 will be by Artemis 3. NASA has a proposed date for that trip, but it could face more postponements.