NASA plans to retry its moon rocket launch on Saturday

For now, NASA will press ahead with preparations for a second launch attempt on Saturday of its new moon rocket, NASA officials said during a news conference on Tuesday,

Mission managers have come up with a plan that they hope will work around an engine problem with the rocket encountered during the first launch attempt on Monday.

The Space Launch System rocket is the modern equivalent of the Saturn V that took NASA astronauts to the moon during the Apollo program half a century ago, and it is the centerpiece of NASA’s Artemis program, which aims to send astronauts back to the moon in the coming years.

This mission, Artemis I, will not have any people on board, but it is a critical test of the rocket and the Orion crew capsule, where astronauts will ride during later missions. During the weekslong journey, Orion will go into orbit around the moon and then return to Earth.

The launch is now scheduled for a two-hour launch window Saturday, starting at 2:17 p.m. Eastern time, although stormy weather could be passing over the launchpad at the Kennedy Space Center in Florida at that time.

The issue that halted the launch Monday was a liquid hydrogen line that did not adequately chill one of the rocket’s four core-stage engines, part of the preparations needed before ignition.

The temperatures of three of the engines were approaching the target of minus 420 degrees Fahrenheit, while the other one was about 40 degrees warmer, said John Honeycutt, the program manager overseeing development of the Space Launch System rocket. Without a chill down, the temperature shock of supercold propellants could crack the metal engine parts.

However, Honeycutt said, the warmer reading might just have been the result of an errant sensor. He said engineers were analyzing other data that could verify that the engines actually were all cold enough.

Mission managers will meet Thursday to decide whether to move ahead with a launch attempt Saturday.

If NASA cannot launch by early next week, it will have to roll the rocket back to the Vehicle Assembly Building. The flight termination system — explosives that can destroy the rocket if it goes off course — needs to be retested 25 days after being installed.