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The uncrewed Artemis I mission will get another launch attempt for a trip around the moon on Saturday.
The two-hour launch window opens at 2:17 p.m. ET on September 3.
After the launch was cleaned up on Monday morning, the launch team spent the rest of the day evaluating the data collected during the attempt. Mission leaders shared an update on Tuesday evening.
The Artemis I stack, which includes the Space Launch System rocket and the Orion spacecraft, continues to be on Launchpad 39B at Kennedy Space Center in Florida.
One of the rocket’s four RS-25 engines, identified as engine #3, failed to reach the proper temperature range required for the engine to start on liftoff.
Engines must be thermally conditioned before super cold propellant passes through them prior to liftoff. To prevent the engines from experiencing temperature shocks, the launch controllers increase the pressure of the central stage liquid hydrogen tank to send some liquid hydrogen to the engines. This is called “bleeding”.
Liquid hydrogen is approximately minus 423 degrees Fahrenheit (minus 252 degrees Celsius).
Engine No. 3 was likely about 30 to 40 degrees hotter than the other engines, which reached about minus 410 degrees Fahrenheit (minus 245 degrees Fahrenheit), said John Honeycutt, space launch system program manager at the Marshall NASA Space Flight Center in Alabama.
Mission managers suspected that the problem with engine #3 was actually a problem with the purge system, rather than the engine itself. A faulty sensor can provide an incorrect engine temperature reading, Honeycutt said.
“The way the sensor behaves doesn’t match the physics of the situation,” Honeycutt said.
The team plans to start the purge 30 to 45 minutes earlier in the countdown than it did on Monday and monitor engine temperature during the purge.
“Going into yesterday’s attempt, we said if we can’t thermally condition the engines, we’re not going to launch,” Sarafin said. “It’s the same posture we’re going in on Saturday.”
Removing and replacing the sensor would be tricky on the launch pad, so the only alternative is to take it back to the Vehicle Assembly Building for servicing, said Charlie Blackwell-Thompson, Artemis Launch Manager at the Exploration Program. NASA Ground Systems.
Several other problems, such as storms, a leak on an 8-inch line used to fill and drain liquid hydrogen from the rocket’s core stage, and a hydrogen leak from a vent valve on the rocket’s intertank the core stage also caused delays Monday morning that prevented liftoff during both one-hour launch windows.
“We have also agreed to do work on the pad to fix the leak we found at the hydrogen tail service mask umbilical,” said Mike Sarafin, Artemis Mission Manager, HQ. from NASA.
The current forecast for Saturday includes a chance of showers and thunderstorms in the morning and early afternoon, so the launch team will keep a close eye on the forecast, said meteorologist Mark Burger, officer US Space Force 45th Weather Squadron launch weather station.
There’s a 60% chance of a weather violation during the launch window, Berger said.
There is still a save opportunity for the launch of the Artemis I mission on September 5 as well.
The Artemis I mission is just the start of a program that will aim to bring humans back to the Moon and eventually land crewed missions on Mars.
Correction: An earlier version of this story misspelled the name of meteorologist Mark Burger.