NASA Scrubs Second Launch Attempt for Artemis I Moon Mission

The failed launch attempt at Florida’s Kennedy Space Center came five days after NASA scrubbed an initial scheduled launch to begin a 1.3-million-mile, 42-day mission to circle the moon and return to Earth, potentially opening the door to a new era in space exploration. 

For much of Saturday morning, NASA engineers worked to troubleshoot the problem behind the scrub—a persistent leak of super-cold liquid hydrogen fuel from a cavity located between the ground and a quick disconnect mechanism on the engine section, according to NASA. 

Because of repair expectations and scheduled launches of other rockets, NASA officials late Saturday said the 322-foot-tall Artemis I stack, including the Space Launch System (SLS) rocket booster and the Orion spacecraft will most likely have to be rolled back to the Vehicle Assembly Building, after spending more than two weeks sitting on Launch Pad 39B. The current launch period for Artemis I ends on Tuesday. 

“We will not be launching in this launch period,” NASA associate administrator Jim Free told reporters during Saturday's news conference. “We are not where we wanted to be.”

Officials have always said they will not launch until they’re fully satisfied that everything is working correctly. With all systems working as expected, engineers would benefit from the best performance data possible for optimizing future missions with astronauts aboard. 

Saturday’s fuel leak was a “much larger leak” than a leak that was discovered during the initial launch attempt on Monday, August 29, Artemis mission manager Mike Sarafin told reporters. 

“We know that when you get above roughly a 4 percent concentration of hydrogen in ambient air you're at risk of having a flammability event or a flammability hazard,” Sarafin said. “We were seeing in excess of that by probably two or three…times our acceptable concentration limit.”

He said “It was pretty clear that we weren’t going to be able to work our way through it like we did on Monday in terms of the managing of the leak.”

A procedure known as a kick-start bleed test also hampered the initial launch attempt. The test involves bleeding liquid oxygen fuel into the SLS core stage’s four RS-25 engines to properly chill them before liftoff. 

"We know we had a bad sensor," said SLS program manager John Honeycutt during a news conference Thursday. During troubleshooting in the days leading up to Saturday’s launch, NASA was able to determine “without a shadow of a doubt” that “good, quality liquid hydrogen was going through the engines," Honeycutt said. However, as a precaution, engineers adjusted their pre-launch procedures Saturday to begin chilling the engines earlier in the countdown. 

Plans call for Artemis I's Orion spacecraft to enter a unique lunar orbit that will send it thousands of miles beyond the moon—farther from Earth than any other human spacecraft—280,000 miles. This highly stable Distant Retrograde Orbit (DRO) requires less fuel and will allow NASA to more effectively evaluate the spacecraft’s capabilities for missions in deep space. Finally, the six-week mission calls for the Orion crew module to return to Earth, splashing down in the Pacific, off San Diego.