NASA is looking to get its Artemis 1 lunar mission off the ground this weekend, despite a recent outage.
The agency announced today (August 30) that it is now targeting Saturday (September 3) for the launch of Artemis 1a critical mission whose first launch attempt was sunk on Monday (29 August) due to a technical problem.
If all goes according to plan, Artemis 1 will be launched from Pad 39B at NASA Kennedy Space Center (KSC) in Florida during a two-hour window opening at 2:17 PM EDT (1817 GMT). You can check it out here on Space.com when the time comes, courtesy of NASA.
As the name suggests, Artemis 1 is NASA’s first mission Artemis programwhich aims to create a sustainable human presence in and around the moon towards the end of the 2020s. It is also the first flight of NASA’s huge new Space Launch System (SLS) rocket, which will send an unmanned Orion capsule on a long journey to lunar orbit and back.
That shakeout cruise was supposed to kick off Monday. During the countdown, however, the Artemis 1 team members noticed that one of the four RS-25 engines powering the SLS core stage was not cooling to the desired low temperature — about minus 420 degrees Fahrenheit (minus 250 degrees Celsius) — before ignition.
Such thermal conditioning, accomplished via “running in” super-cold liquid hydrogen propellant, ensures there’s no jolt when the engines fire up, mission team members have explained. Engines 1, 2 and 4 got close to the target during the countdown, but number 3 remained relatively far off limits, at about minus 380 degrees Fahrenheit (minus 230 Celsius), John Honeycutt, manager of the SLS program at NASA’s Marshall Space Flight Center in Alabama, said at a news conference tonight.
The Artemis 1 team was unable to resolve the issue in time during Monday’s countdown, so the launch attempt was cancelled. But Honeycutt and others on the mission team think they have it under control now: they suspect it comes down to a faulty temperature sensor on engine 3.
“I think we understand the physics about how hydrogen performs, and the way the sensor behaves doesn’t match the physics of the situation,” Honeycutt said at tonight’s press conference. Readings from other sensors suggested Engine 3 was getting proper levels of liquid hydrogen while bleeding, he added.
Replacing the sensor would likely require the Artemis 1 stack to be rolled from Pad 39B and back to KSC’s massive Vehicle Assembly Building, Honeycutt and others said during the briefing. The Artemis 1 team does not consider that necessary at this time and instead plans to continue with another launch attempt on Saturday.
The team plans to make a few adjustments to the countdown plan — for example, start the engine cooling process 30 to 45 minutes earlier than last time. And they will continue to analyze data and map out scenarios in the coming days to make sure that the current approach is indeed justified and sensible, Honeycutt said.
“We need to continue studying the data,” he said. “We have to put together a flight idea, expecting that we won’t get better results with that Engine 3 bleed sensor.”
Such problems are often solved during a “wet dress rehearsal,” a series of tank tests and simulated launch countdowns that help vet a brand new rocket for its maiden flight. The Artemis 1 team made several attempts to wet dress on Pad 39B this spring, but they encountered several technical issues and ended up skip some steps. The wet-dress attempts never put Artemis 1 in the “engine bleed” configuration where the problem arose on Monday.
Even if all technical analysis supports a Saturday afternoon launch attempt, there’s no guarantee that Artemis 1 will go off track that day. Mother Nature will also have something to say, and the news there is a bit iffy.
Mark Berger, a launch weather officer with the US Space Force’s 45th Weather Squadron, said the latest forecasts show a threat of rain and thunderstorms along Florida’s Space Coast on Saturday. There is a 60% chance of a weather violation during Saturday’s launch window, Berger said at tonight’s press conference. But he expressed his optimism that the weather will clear up during the window at some point, giving Artemis 1 a chance to take off.
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