NASA canceled plans to load its new space launch system moon rocket with more than 750,000 gallons of liquid oxygen and hydrogen for fuel on Sunday due to problems with launch pad support equipment, which must prevent build-ups of dangerous gas. The team plans to try again on Monday.
The massive 322-foot-tall SLS rocket was towed to launch pad 39B at Kennedy Space Center on March 18 for the countdown to the dress rehearsal to clear the way for its first launch earlier this summer by an unmanned Orion crew – Send the capsule on a flight beyond the moon and back.
The countdown began Friday afternoon and reached the T-minus 6-hour point early Sunday, when engineers planned to begin pumping 196,000 gallons of liquid oxygen and 537,000 gallons of liquid hydrogen into the rocket’s core stage. An additional 22,000 gallons of cryogenic oxygen and hydrogen fuel were to be loaded into the upper stage.
Once fully loaded, the team scheduled two terminal countdown practice runs, one up to about T-minus 33 seconds and one up to less than 10 seconds, to test recycling methods and ensure the system is ready for the real world.
But the countdown was held up to give engineers time to get back on schedule after delays caused by blustery weekend weather and then fan problems that put pressure on the rocket’s mobile launch platform. The fans provide positive pressure within the structure to prevent accumulation of free hydrogen during the fueling process.
After several hours of troubleshooting on the pad and in the launch control center, the mission managers decided to cancel today’s test to give the engineers time to fix the problem.
“Fans are needed to provide positive pressure to the enclosed areas inside the mobile launch vehicle to keep out hazardous gases,” NASA said in a blog post. “Technicians without this skill are unable to safely load the propellants into the core stage and the (upper) stage of the rocket.”
Former shuttle program manager Wayne Hale said he wasn’t surprised that problems arose in NASA’s first attempt to survive a complex countdown on the largest, most powerful rocket the agency has ever built.
“Exactly the problem with the floor system that I expected,” he tweeted. “Short-term delay. The first time, these kinds of problems are expected.”
NASA’s Exploration Ground Systems group tweeted, “This is the first time we have been conducting the integrated cryo ops on the pad and the teams are taking classes as they progress through countdown procedures. The events taking place now represent a great training and learning opportunity for the previous team to start.”
Equipped with two augmented solid fuel boosters and a core stage powered by four modified Space Shuttle main engines, the SLS rocket will tip the scales at launch at 5.75 million pounds and generate 8.8 million pounds of thrust,1, 3 million pounds more thrust than NASA’s legendary Saturn 5 rocket.
Development of the “mega rocket” is years behind schedule and billions over budget, but NASA hopes to jump-start its Artemis lunar program by launching the first SLS earlier this summer, followed by a manned flight around the planet Moon in 2024. The first in a series of landings by NASA astronauts is scheduled for 2025 or shortly thereafter.