(CNN) — The Artemis I mission launch team is preparing for another countdown beginning this Saturday morning, after a series of problems prevented its liftoff on Monday.
The launch window opens at 2:17 pm ET and closes at 4:17 pm ET on Saturday. Currently, weather conditions are 60% favorable during the launch window, according to Meteorologist Melody Lovin, who predicts that the weather will not be an “obstacle” for the launch.
The Artemis I stack, which includes the Space Launch System rocket and the Orion spacecraft, remains on Launch Pad 39B at the Kennedy Space Center in Florida.
Although launch is not guaranteed on Saturday, “we’re going to try,” Mike Sarafin, director of the Artemis mission, said during a news conference Thursday night. And while the launch team will take a little more risk heading into the launch attempt, those are acceptable risks that the team is comfortable with, Sarafin said. The Artemis I mission is unmanned.
One of the areas where the team is taking more risks is the conditioning of the #3 engine, which contributed to the blocking of the launch attempt on Monday (Aug 29). Another is a crack in the core stage intertank foam, which could rupture and hit part of the solid rocket booster, but the team believes the chances of that happening are very low, according to Sarafin.
It’s “a minimal increase in risk,” Sarafin said, but “clearly we’re ready to fly.”
“We had a plan for the August 29 launch attempt. It used the sensors to help confirm proper thermal conditioning of the engines. We had trained on that plan, and then we ran into other problems,” Sarafin said.
“We went off script in terms of normal tank operation, and the team did a fantastic job of managing a dangerous condition. One of the worst things you can do when you’re in a dangerous situation is go even further off script.” .
After reviewing the data, the team has a plan to move forward with the launch.
Work was carried out on the launch pad to fix two different hydrogen leaks that occurred on Monday. The team also completed a risk assessment of the engine conditioning issue and a foam crack that also appeared, according to NASA officials.
What happened on the first launch attempt?
On Monday, a sensor on one of the rocket’s four RS-25 engines, identified as Engine No. 3, showed that the engine was unable to reach the proper temperature range required for the engine to start at liftoff.
The engines must be thermally conditioned before supercooled propellant flows through them prior to takeoff. To prevent the engines from experiencing temperature shocks, launch controllers increase the pressure of the core-stage liquid hydrogen tank to send some of the liquid hydrogen to the engines. This is known as “purging”.
Now the team has determined that it was a faulty sensor that provided the reading.
“We had time to go back and look at the data and compare many data sources and do some independent analysis that confirmed it’s a faulty sensor,” said John Honeycutt, SLS program manager at NASA’s Marshall Space Flight Center in Huntsville, Alabama. “We’re passing a good quality propellant through the engine.”
On launch day, the team will ignore the faulty sensor, said John Blevins, SLS chief engineer.
The rocket’s automated launch sequencer checks temperature, pressure and other parameters. The faulty sensor, which is not part of the sequencer, is not considered a flight instrument, Blevins explained.
How to see the launch of Artemis I this Saturday?
The team plans to start the purge earlier in the countdown than what happened on Monday. The countdown to launch will resume on Saturday at 4:37 am ET during a planned delay. At that time, mission managers will receive a weather briefing and decide whether the team should proceed with loading propellant into the rocket. The purge is expected to occur around 8 a.m. ET, said Charlie Blackwell-Thompson, Artemis launch manager for NASA’s Exploration Ground Systems Program.
The two-day countdown is no longer necessary, unlike the first launch attempt, “because many of the configurations necessary for launch are already in place,” according to NASA.
NASA’s live coverage will begin at 5:45 am ET on its website and on its television channel.
“We have to show up, be prepared and see what the day brings,” Sarafin said.
If the mission succeeds in launching on Saturday, it will make a trip around the Moon and splash down in the Pacific Ocean on October 11.
In case it is not achieved, the Artemis I mission could also launch on September 5.
The Artemis I mission is just the beginning of a program that aims to return humans to the Moon and eventually land manned missions on Mars.