NASA will make a second attempt to launch its powerful next-generation moon rocket on Saturday after engine troubles halted the first planned launch earlier this week.

The 322-foot (98-meter) Space Launch System would be the most powerful rocket ever launched by the US space agency.

However, the weather forecast predicts just a 40% chance of favorable launch conditions on Saturday, and NASA acknowledges there's still a chance the same issues that plagued the first attempted launch could reappear.

NASA's rocket program manager John Honeycutt said the upcoming second attempt on Saturday would be better than "sitting around scratching our heads [and wondering] was it good enough or not.''

"Based on what I've heard from the technical team today, what we need to do is continue to pore over the data and polish up our plan on putting the flight rationale together,'' he said.

The space agency also said that Monday's aborted takeoff was still an invaluable trouble-shooting experience.

Back to the moon

The launch will not only test the rocket itself, but also the Orion crew capsule that sits on top. The unmanned capsule will contain mannequins, and it is scheduled to orbit the moon to see whether the capsule is safe enough for human spaceflight in future.

The long-awaited launch would kick off NASA's moon-to-Mars Artemis program — the agency's first major lunar expedition since the Apollo program of the 1960s and '70s. Since then, US human spaceflight efforts have focused on low-Earth orbit with space shuttles and the International Space Station.

The end goal is to work with overseas space agencies and the private sector to establish a long-term lunar base from which to launch future human voyages to Mars.