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 on 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.
“The way the sensor is behaving doesn’t line up with the physics of the situation,” Honeycutt said. “And so we will be looking at all the other data that we have, to use it to make an informed decision whether or not we’ve got the engine, all the engines chilled down or not.”
That could mean that on Saturday, the countdown will continue, even if the same temperature readings occur.
“What we need to do is continue to pore over the data and then polish up our plan on putting the flight rationale together,” Honeycutt said. “I think we’ve got enough data to do that, but we’ll have to let the data guide us.”
In addition, for the next launch attempt, the chill-down test will be performed 30 minutes to 45 minutes earlier to reproduce what was done during a successful test firing of the core stage’s engines last year at the Stennis Space Center in Mississippi.
This week, technicians will also take a look at a leak that cropped up during the filling of the rocket’s propellant tanks on Monday and tighten connections in the fuel line that connects to the bottom of the rocket. That work can be done at the launchpad without the rocket returning to the Vehicle Assembly Building, an immense facility used to assemble and service rockets.
During the launch attempt Monday, engineers were able to stem the leak and resume the flow of hydrogen into the tank.
Mission managers will also 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, and that can only be done in the Vehicle Assembly Building.
Even as engineers try to fix the technical issues, other variables are out of NASA’s control.
Saturday’s weather conditions “favor showers and possibly a few thunderstorms moving in from the coast during the morning and early afternoon hours,” said Mark Burger, the launch weather officer with the U.S. Space Force’s 45th Weather Squadron.
Burger estimated the probability of a weather violation during the launch window “in the neighborhood of 60%,” but added there could be pockets of clear skies between.
“We have two hours to work with, and these showers tend to have quite a bit of real estate between them,” he said. “So I still think we have a pretty good opportunity weather-wise to launch on Saturday.”