“We won’t be launching during this launch period,” said Jim Free, associate administrator for NASA’s Exploration Systems Development Mission Directorate. “We’re not where we want to be.”
The stacks, including the Space Launch System rockets and Orion spacecraft, must be rolled back to the vehicle assembly building unless they receive an exemption from those operated by the U.S. Space Force, Free said.
NASA Administrator Bill Nelson reminded that the shuttle was sent back to the vehicle assembly building 20 times before launch, noting that the cost of two scrubs was far less than a failure.
“We’re not going to launch until we think it’s right,” Nelson said. “These teams worked on it, and that’s what they came to. I think it’s part of our space program where safety is paramount.”
At 11:17 a.m. ET, three hours before the launch window, the cleanup took place.
Artemis I was due to take off on Saturday afternoon, but those plans were scrapped after team members discovered a liquid hydrogen leak, and they spent most of the morning trying to fix the problem. Liquid hydrogen is one of the propellants used in the rocket’s large core stage. Despite trying various troubleshooting procedures, the leak prevented the launch team from filling the liquid hydrogen tanks.
Previously, there was a small spill in the area, but it turned into a bigger one on Saturday. The team believes that the overpressure event may have damaged the soft seal at the liquid hydrogen junction, but they need to watch carefully.
“This was not a controlled leak,” said Mike Sarafin, the Artemis mission manager.
This is the second time in a week that the space agency has been forced to stop the countdown to launch due to technical problems. Monday’s first launch attempt was called off after several problems, including a system used to cool the rocket’s engine before liftoff and various leaks while the rocket was being refueled.
At 7:15 a.m. ET Saturday, a leak of liquid hydrogen was detected in the quick-disconnect chamber, which supplies the rocket’s core-stage engine section with hydrogen. That’s not the same as the leak that occurred ahead of Monday’s Scrub launch.
The launch controller preheats the lines in an attempt to obtain a tight seal and restore the flow of liquid hydrogen before the leak occurs again. According to NASA, they stopped the flow of liquid hydrogen and continued to “close the valve used to fill and drain it, then use helium to increase pressure on the ground transmission line to try to reseal it”.
This troubleshooting plan was unsuccessful. The team tried their 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 the launch had a 60 percent chance of favorable weather conditions.
The Artemis I stack, which includes the Space Launch System rocket and Orion spacecraft, continues on Launch Pad 39B at the Kennedy Space Center in Cape Canaveral, Florida.
The Artemis I mission is just the beginning of a plan to send humans back to the moon and eventually a crewed mission to Mars. Problems in the first two scrubs did not cause any delays to future Artemis missions, Nelson said.
Over the past few days, the launch team has spent some time addressing issues such as hydrogen leaks that popped up ahead of Monday’s planned launch before being cleared. The team also completed a risk assessment for engine tuning issues and foam cracking, according to NASA officials.
Artemis mission manager Mike Sarafin said both are considered acceptable risks ahead of the countdown to launch.
On Monday, a sensor on one of the rocket’s four RS-25 engines, identified as Engine 3, reflected that the engine was unable to reach the proper temperature range for the engine to start on liftoff.
The engine needs to be thermally conditioned before the supercooled propellant flows through the engine before liftoff. To protect the engine from any temperature shock, the launch controller gradually increased the pressure of the core-stage liquid hydrogen tank several hours before launch to deliver a small amount of liquid hydrogen to the engine. This is called “bleeding”.
John Blevins, chief engineer of the Space Launch System, said the team had determined it was a bad sensor that was providing readings — and they planned to ignore the faulty sensor and move on.
Once Artemis 1 launches, Orion’s journey will last 37 days as it travels to the Moon, orbits the Moon and returns to Earth — a total of 1.3 million miles (2.1 million kilometers).
While the passenger list doesn’t include any humans, there are passengers: three mannequins and a plush Snoopy toy will ride the Orion.
Expect to see a view similar to the Earthrise first shared during the Apollo 8 mission in 1968, but with far better cameras and technology.
CNN’s Kristen Fisher contributed to this story.