NASA announced it would continue launching its $4.1 billion Artemis I rocket to the moon on Saturday.
The two-hour launch window opens at 2:17 p.m. and teams will reconvene on Thursday for another review before the countdown officially begins.
Space Launch Delta 45 Weather Squadron updated its forecast on Thursday to predict a better chance of good weather, now 60% chance for good conditions, up from the initial forecast of 40% on Tuesday. The Monday night backup window has a chance of increasing good weather to 70%.
“I’m optimistic we’ll have clear air to work with in the Saturday afternoon attempt,” Mark Burger, 45th Weather Squadron launch officer, said at a press conference Tuesday evening. . “However, again, the likelihood of a weather violation at any point in the countdown still seems pretty high to me.”
If it rubs on Saturday, the next window falls on Labor Day, a 90-minute opportunity that opens at 5:12 p.m., which NASA says would still be possible since NASA only needs 48 hours to replenish all the gases needed to refuel. the tank.
The massive Space Launch System combination topped with the Orion spacecraft passed through several roadblocks on Monday morning during NASA’s first shot to send the Artemis I mission into space, but ultimately an engine problem forced a scrub.
The culprit was something called the purge system, which feeds the core stage cryogenic thruster into the four RS-25 engines at its base. Sensors showed during a bleed test ahead of Monday’s aborted takeoff that one of the engines had not cooled to acceptable levels.
All four must have their temperature managed so that they are not stressed by the liquid hydrogen (LH2), which is cooled to minus 423 degrees Fahrenheit, when it begins to flow at full throttle into the engines on takeoff. .
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 boosters provides 8.8 million pounds of thrust for SLS on takeoff.
Other issues during Monday’s attempt involved the loading of the cryogenic thrusters, which needed adjustment when a potential hydrogen leak was detected in one of the umbilical feed lines. To address both of these issues, NASA is changing how the Saturday countdown will run.
“We agreed on what was called the first option, which was to operationally change the loading procedure and start our engine cooling earlier,” said mission manager Mike Sarafin. Artemis. “We have also agreed to do work on the pad to fix the leak we found in the umbilical of the hydrogen tail service mast.”
NASA SLS director John Honeycutt said teams weren’t entirely certain if the engine temperature was really off target, and it could have been a faulty sensor based on the readings. other equipment on site.
“I think we understand the physics of how hydrogen works and not the behavior of the sensor,” he said, noting that “that doesn’t fit the physics of the situation.”
He said replacing the sensor on the launch pad would be tricky and would require restoration, so instead they’ll “fly using the data we have access to today.”
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Sensors from Monday’s attempt showed three of the four motors were within 10 degrees of a minus 420 degrees Fahrenheit target while the fourth, the one that convinced officials to scrub, was around 40 degrees warmer, Honeycutt said.
“We’ll try to pitch,” Sarafin said. “And you know going into that previous attempt – [Monday’s] attempt – you know, we said if we couldn’t thermally condition the motors, we weren’t going to launch. And it is the same posture in which we are going on Saturday. I don’t see it as different.
If and when it lifts 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 weeks-long mission to orbit the moon 1.3 million miles and return home as the fastest spacecraft ever man-rated at over 24,500 mph generating nearly 5,000 degrees Fahrenheit on reentry.
The goal is to test the limits of the launch system and spacecraft so it can transition to human missions, including Artemis II, an orbital lunar mission scheduled for 2024, and Artemis III, which aims to bring humans back, including the first woman on the lunar surface since 1972. This flight could take place as early as 2025.
But Artemis I must take off first.
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