NASA announced that it would seek to launch its $4.1 billion Artemis I rocket to the moon on Saturday.
The two-hour launch window opens at 2:17 p.m. and the teams will meet on Thursday for another review before the official start of the countdown.
The Space Launch Delta 45 weather squadron updated its forecast Thursday to predict a better chance of good weather, now a 60% chance for good conditions, above the initial prediction of 40% on Tuesday. The backup window on Monday night has odds of good weather rising to 70%.
“I’m optimistic that we’ll have some clear air to work with during the Saturday afternoon attempt,” Mark Burger, launch officer for the 45th Weather Squadron, said at a news conference Tuesday night. “However, again, the probability of a weather violation at any point in the countdown still seems pretty high to me.”
If you start on Saturday, the next window falls on Labor Day, a 90-minute window that opens at 5:12 p.m. the tank
The massive combination of the Space Launch System topped off with the Orion spacecraft hit several hurdles Monday morning in NASA’s first attempt to send the Artemis I mission into space, but ultimately an engine problem forced a washdown.
The culprit was what’s known as a bleeder system, which feeds cryogenic propellant from the core stage to the four RS-25 engines at its base. Sensors showed during a purge test prior to Monday’s aborted takeoff that one of the engines did not cool to acceptable levels.
All four need to control their temperature so they’re not stressed by liquid hydrogen (LH2), which cools to minus 423 degrees Fahrenheit, when it starts flowing full speed to the engines on takeoff.
The LH2 combined with liquid oxygen cooled to minus 297 degrees Fahrenheit provides 2.2 million pounds of thrust, which when combined with two solid rocket propellants provides 8.8 million pounds of thrust for SLS at liftoff.
Other problems during Monday’s attempt involved charging the cryogenic thrusters, which needed adjustment when a possible hydrogen leak was detected in one of the umbilical feed lines. To deal with both problems, NASA is changing the way Saturday’s countdown will proceed.
“We agreed on what was called option one, which was to operationally change the loading procedure and start cooling our engine earlier,” said Artemis mission manager Mike Sarafin. “We also agreed to work on the platform to address the leak we saw in the hydrogen tail service mast umbilical.”
NASA SLS manager John Honeycutt said the teams weren’t entirely sure if the engine temperature was actually off target and could have been a faulty sensor based on readings from other teams on site.
“I think we understand the physics of how hydrogen works and not how the sensor behaves,” he said, noting that “it doesn’t line up with the physics of the situation.”
He said replacing the sensor on the launch pad would be tricky and would require a rollback, so instead “they’ll fly out using the data we have access to today.”
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Sensors from Monday’s attempt showed that three of the four engines were within 10 degrees of a target of minus 420 degrees Fahrenheit, while the fourth, the one that convinced managers to scrub, was about 40 degrees hotter, Honeycutt said.
“We’re going to try to pitch,” Sarafin said. “And you know going into this earlier attempt: [Monday’s] I try, you know we said if we can’t thermalize the engines, we’re not going to take off. And that’s the same stance that we’re going into on Saturday. I don’t see it any different.”
If and when it does take off, the rocket would become the most powerful ever launched from Earth, surpassing the 7.6 million pounds of thrust produced by the Saturn V rockets of the Apollo missions to the Moon.
Artemis I is supposed to send the uncrewed Orion capsule on a multi-week mission to orbit the moon traveling 1.3 million miles and return home arriving as the fastest spacecraft ever rated by humans at over 24,500 mph generating about 5,000 degrees Fahrenheit on re-entry. . .
The goal is to test the limits of the launch system and spacecraft so it can move on to human missions, including Artemis II, an orbiting lunar mission scheduled for 2024, and Artemis III, which aims to return humans, including the first woman to the lunar surface. since 1972. That flight could arrive as early as 2025.
But first Artemis I have to take off.
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