Artemis I was scheduled to take off on Saturday afternoon, but those plans were scrapped after team members discovered a liquid hydrogen leak that they spent most of the morning trying to fix. Liquid hydrogen is one of the propellants used in the rocket’s large nuclear stage. The leak prevented the launch team from filling the liquid hydrogen tank, despite several troubleshooting procedures.
It is the second time in a week that the space agency has had to stop the launch countdown due to technical problems. The first launch attempt, on Monday, was called off after several problems arose, including with a system intended to cool the rocket’s engines prior to launch and several leaks that developed while the rocket was being fed.
The liquid hydrogen leak was discovered at 7:15 a.m. ET Saturday in the quick-disconnect cavity that feeds the rocket with hydrogen in the engine section of the nuclear stage. It was a different leak than one that occurred prior to Monday’s scrubbed launch.
The launch controllers warmed up the line in an attempt to get a good seal and resumed the flow of liquid hydrogen before another leak occurred. They stopped the flow of liquid hydrogen and proceeded to “close the valve used to fill and drain it, then increase the pressure on a ground transfer line using helium to try again.” shut down,” NASA said.
That troubleshooting plan was unsuccessful. The team tried the first plan again to warm up the line, but the leak recurred after they manually restarted the flow of liquid hydrogen.
Weather officer Melody Lovin said there was a 60% chance of favorable weather conditions for the launch.
The Artemis I stack, which includes the Space Launch System rocket and the Orion spacecraft, will remain on Launchpad 39B at the Kennedy Space Center in Cape Canaveral, Florida.
The Artemis I mission is just the beginning of a program that aims to return humans to the moon and eventually land manned missions on Mars.
There is still a backup option for the Artemis I mission that launches on September 5 and 6.
In recent days, the launch team has taken time to address issues, such as hydrogen leaks, that occurred before Monday’s scheduled launch before it was scrubbed. The team also completed a risk assessment of an engine conditioning problem and a foam crack that also surfaced, according to NASA officials.
According to Artemis mission manager Mike Sarafin, both were considered acceptable risks en route to the launch countdown.
On Monday, a sensor on one of the rocket’s four RS-25 engines, identified as engine #3, indicated that the engine was unable to reach the proper temperature range necessary for the engine to start on takeoff.
The engines must be thermally conditioned before super-cold propellant flows through them before taking off. To prevent the engines from experiencing temperature shocks, launch controllers gradually increase the pressure of the liquid hydrogen tank at the core stage in the hours before launch to send a small amount of liquid hydrogen to the engines. This is known as a ‘bleeding’.
The team has since determined that it was a bad sensor that gave the reading — they plan to ignore the faulty sensor, according to John Blevins, chief engineer of Space Launch Systems.
Once Artemis I is launched, Orion’s journey will take 37 days as it travels to the moon, orbits it, and returns to Earth — a total of 1.3 million miles (2.1 million kilometers).
While the passenger list doesn’t include people, there are passengers: three mannequins and a plush Snoopy toy will ride in Orion.
Expect to see views of Earthrise similar to what was first shared during the Apollo 8 mission in 1968, but with much better cameras and technology.