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NASA teams investigating pad hardware at Kennedy Space Center found a potential culprit behind a leaky hydrogen line that scrubbed the Artemis I moon mission’s last attempt, making way for a fueling test this week.
Managers and engineers have already started preparing for their arrival at the Launch Control Center starting Monday evening, a process that will run through what is essentially a mock countdown similar to launch day. At 3:40 am EDT Wednesday, Sept. 21, teams will clear the Space Launch System rocket’s pad 39B and slowly begin what until now has been a finicky fueling process.
The necessity for Wednesday’s test is being driven by two previous launch attempts, both of which had to be scrubbed due to technical issues with the 322-foot rocket, which uses leftover space shuttle program hardware. If all goes well, it could lead to a third launch attempt at 11:37 am EDT Tuesday, Sept. 27.
In late August, it appeared one of four RS-25 main engines failed to reach the right pre-launch temperature, but NASA officials later determined the bad reading was due to a faulty sensor. During the second attempt earlier this month, a major leak of liquid hydrogen – one of SLS’ two propellants along with liquid oxygen – forced a scrub after the tank could not be filled.
Why Artemis flies on Hydrogen:Hydrogen is NASA’s fuel of choice for Artemis I, but it is also difficult to manage
Now teams think at least part of the second issue was caused by damage to a seal in a hydrogen quick-disconnect, or QD. A NASA official said the “witness mark,” or indentation, was likely caused by foreign object debris in the system and, despite its small size at 0.01 inches, cannot be ruled out as a contributor.
“That doesn’t sound like a lot, but we’re dealing with hydrogen, the smallest particle on the atomic chart,” Mike Sarafin, NASA’s Artemis I mission manager, said during a pre-test briefing Monday. “So an indentation of that size does provide an opportunity for a pressurized gas to leak through.”
Liquid hydrogen is a finicky propellant. Not only does it need to be chilled to colder temperatures than other options like kerosene or methane, but its small size means it can even be “absorbed” by metals and cause damage. It also has to be seriously pressurized, easily exposing flaws or leaks in the loading system.
Artemis I plan moving forward
By 3 pm EDT Wednesday, or about 12 hours after teams clear pad 39B, NASA hopes to have conducted a successful propellant loading test. But in order to get there, officials said some modifications will be made during the countdown and fueling processes.
First, the seals in the hydrogen QD at pad 39B were replaced. That will allow for a “kinder, gentler” loading process designed to pump the chilled hydrogen at slower rates and hopefully avoid thermal shock.
“We’re trying to minimize both pressure spikes and thermal spikes,” Jeremy Parsons, deputy manager of ground systems at KSC, said Monday. “What we’re going to be doing is bringing up the pressure … so it’s going to be a slow and steady ramp.”
“With hydrogen in particular, you’re talking very, very extreme temperatures … so really trying to slowly introduce some of those thermal differences and reduce thermal and pressure shocks,” he said.
Although NASA isn’t sure if damage to the seal caused the level of leakage seen during the last attempt, tests so far plus Wednesday’s nearly full countdown should provide the answers engineers need.
For live coverage of the fueling test, visit floridatoday.com/space starting at 7:30 am EDT Wednesday.
After the fueling test
If all goes well with propellant loading, NASA managers will turn their attention to the Space Force, which is responsible for public safety at Kennedy Space Center and neighboring Cape Canaveral Space Force Station.
Although all might be well fueling-wise, the Artemis I rocket’s flight termination system designed to destroy SLS in the event of an emergency has passed its expiration date. The batteries that power the system need to be certified by the Space Force every 25 days.
NASA hopes to get the FTS extended via waiver, but will wait until after Wednesday’s fueling test to move forward on that. The termination system is not needed during the test.
If the fueling test goes well and the Space Force grants the waiver, that will pave the way for liftoff during a 70-minute window that opens at 11:37 am EDT Tuesday, Sept. 27. A backup window is available at 2:52 pm Sunday, Oct. 2.
“The launch criteria for each vehicle are used to develop mission rules that govern the allowable flight behavior to ensure public safety, which is the foremost job of the
Eastern Range,” Space Launch Delta 45 said in a statement. “SLD 45 and the Eastern Range have enjoyed a trusted partnership with NASA that dates back to the earliest days of human spaceflight.”
For the latest, visit floridatoday.com/launchschedule.
Contact Emre Kelly at firstname.lastname@example.org or 321-242-3715. Follow him on TwitterFacebook and Instagram at @EmreKelly.
Current launch windows for Artemis I:
Tuesday, Sept. 27:
- Launch time: 11:37 am EDT
- Launch window: 70 minutes
- Orion splashdown: Nov. 5
Sunday, Oct. 2:
- Launch time: 2:52 pm EDT
- Launch window: 110 minutes
- Orion splashdown: Nov. 11
Visit floridatoday.com/space three hours before each window opening for live video and real-time updates.