The launch of Artemis I, NASA’s most powerful rocket has been canceled for the second time.
NASA engineers said a liquid hydrogen leak was discovered as the launch crew prepared to fuel it for a critical test flight on Saturday.
The Space Launch System rocket was originally set to launch from the Kennedy Space Center in Cape Canaveral, on Monday but was delayed after one of the rocket’s engines failed to condition to the correct temperature.
NASA said in a statement on its website Saturday morning that engineers have halted the flow of liquid propellant into the core stage, which serves as the rocket’s backbone, while they investigate the problem.
The 322-foot (98-meter) rocket, the most powerful ever developed by NASA, has over 1 million gallons of fuel loaded into it for the second time this week.
The Artemis program plans to send the people back to the moon for the first time since 1972 in subsequent missions.
The Orion exploration spacecraft, which will be unmanned, is planned to travel more than 40,000 miles past the moon before returning to Earth.
NASA hopes to send astronauts, including the first woman and person of color to set foot on the moon, to the moon’s surface by 2025 or 2026.