Artemis-2 moist costume rehearsal was the primary time the powered-up built-in fueled stack might discuss to NASA. Orion was configured for flight, the closeout crew safely closed the hatches & white room, the entry arm bridge retracted superb, the rocket was totally fueled, however a pesky hydrogen leak spiked to cutoff limits after they entered terminal countdown & pressurized the core stage.
In a news conference Feb 3, mission management mentioned they’ll repair the leak on the pad, so no rollback to the VAB is deliberate. The issue is on the tail service mast umbilical (TSMU) cavity, on the base of the rocket between the place the flight and floor plate come collectively.
The flight-side interface with the leak is advanced and delicate to circulate charges & pressures, & makes use of a pressure-assisted seal. Within the slow-fill part every thing was okay, however as they step by step elevated strain into fast-fill the leak began. They know the best way to handle it from Artemis-1, let the seal & interface get heat & alter strain to remain inside leak limits to get the tank full. NASA has a leak restrict cutoff of 16% for SLS. The leak ranged from 12-14%.
When ops entered Terminal Rely & pressurized the core stage, the leak rapidly spiked, stopping the countdown. It’s what WDR is for, testing every thing as will probably be on launch day and addressing points in order that they aren’t an issue when it’s time to do the actual factor.
Employees will entry the interface plate and have a look at the seal
The staff is now reviewing knowledge & investigating which bleed line is concerned. They should entry the interface plate & take away & examine the seal. There could also be a misalignment, a deformation or particles on the seal.
Related leaks with Artemis-1 have been on the ground-side. Engineers made quite a few modifications & enhancements after. No leak occurred on that aspect for Artemis-2 WDR.
“After Artemis I, with the challenges we had with the leaks, we took a reasonably aggressive strategy to do some component-level testing with a few of these valves and the seals, to grasp their habits,” mentioned John Honeycutt, chair of the Mission’s Administration Workforce.
“We obtained an excellent deal with on that relative to how we set up the flight-side and the ground-side interface, however on the bottom, we’re fairly restricted in how a lot realism we will put into the take a look at. We attempt to take a look at like we fly, however it is a very advanced interface. Once you’re coping with hydrogen, it’s a small molecule. It’s extremely energetic.”
NASA thinks rollout could also be a contributing issue behind the leaks
Within the press convention, NASA famous that shifting the large rocket could also be an element behind the leak. There isn’t sufficient knowledge to show it, however the TSMU is mated to the stack throughout rollout. Engineers can’t totally characterize the setting & stresses from high to backside throughout these delicate strikes, the identical means they’ll predict stresses whereas on the pad. That’s one purpose why they by no means need to transfer the stack until they don’t have any alternative.
Artemis-2 can keep on the pad by March, however past that it must rollback to the VAB so technicians can service the higher stage batteries. The cast-life on the SRBs is nice to 2028, & Orion’s CO2 scrubbing system is checked out to mid-2027.
One of many large issues NASA hoped to do however couldn’t is get by terminal rely to T-0 (liftoff). The staff desires to confirm a 3-minute maintain functionality, demonstrating that the SLS cryo propellant programs can maintain in a launch-ready state. Additionally they need to execute a recycle the place they’ve a cutoff within the countdown and are available again to focus on a brand new T-0. Each might be achieved within the subsequent WDR.
March 6-9 and March 11 are the following launch alternatives.
