NASA defends decision to proceed with modified SLS countdown test

WASHINGTON — NASA officers defended their determination to proceed with a modified model of a countdown rehearsal for the House Launch System that doesn’t contain fueling the rocket’s higher stage, saying they’ll wait till after the check to find out the subsequent steps towards launch.

Throughout an April 11 name with reporters, NASA SLS managers stated they have been able to proceed with a 3rd try and load the SLS at Launch Advanced 39B with liquid hydrogen and liquid oxygen propellants and undergo a countdown that stops simply earlier than ignition of the core stage’s 4 RS-25 engines. That fueling and terminal countdown is scheduled for the afternoon of April 14.

NASA introduced April 9 it was modifying the plan for the third try after discovering a defective helium verify valve within the rocket’s higher stage, the Interim Cryogenic Propulsion Stage (ICPS). The company introduced it is going to carry out solely “minimal propellant operations” on that higher stage through the moist costume rehearsal, and won’t utterly fill the stage with liquid hydrogen and liquid oxygen as initially deliberate.

“We consider that that is the most suitable choice transferring ahead,” stated Charlie Blackwell-Thompson, NASA Artemis launch director, through the name. “We consider that we’ll be capable to meet nearly all of our check targets and supply us with a fairly good set of information previous to rollback” to the Car Meeting Constructing (VAB).

She and different company officers argued that they may nonetheless get priceless information although the check falls in need of the moist costume rehearsal initially deliberate, the place the core and higher phases are each totally loaded. Blackwell-Thompson stated there are about 25 “vital occasions” within the terminal part of the countdown, from T-10 minutes to the cutoff just below T-10 seconds. Solely two, she stated, have been particular to ICPS.

NASA plans to attend till after the check is full to find out what to do subsequent in getting ready the SLS for launch. “We’ll check out the place we’re at and ask ourselves what’s the correct subsequent step,” stated Tom Whitmeyer, deputy affiliate administrator for frequent exploration methods improvement at NASA Headquarters. “There’s a worth of taking a step-by-step strategy.”

There shall be a small quantity of propellant that may move into the ICPS through the check, stated John Blevins, NASA SLS chief engineer, sufficient to chill methods to cryogenic temperatures. That may cease simply earlier than “quick fill” of the propellant tanks would start.

“That’s a very necessary piece of information to get,” stated Blackwell-Thompson. “Traditionally, if you see leaks, particularly with one thing small like hydrogen, it’s normally if you get right down to cryogenic temperatures.”

Blevins stated it was too quickly to say if NASA might want to do one other moist costume rehearsal that features tanking the ICPS, explaining that it’ll depend upon information collected from different methods from the upcoming check. “If that lacking information have been the one lacking information, and each mannequin acted completely, I feel we’d look lengthy and exhausting at whether or not we would have liked to or not,” he stated, including that it wasn’t attainable to do a tanking check of the ICPS alone with out additionally loading the core stage.

As soon as the SLS is rolled again to the VAB, he stated changing the defective helium verify valve needs to be simple. “Simple to get to, straightforward to alter out.”

He declined to invest on why the valve, which he described as a “high-reliability half,” malfunctioned. “It’s considerably of an sudden end result, an sudden failure,” he stated.

NASA has additionally declined to invest on what these points imply for the schedule of the Artemis 1 launch itself. That mission has launch home windows of June 6 to 16, June 29 to July 17 and July 26 to Aug. 9, outlined by orbital mechanics of the Earth and moon and different mission constraints. Whitmeyer stated there aren’t any points with the SLS or Orion spacecraft that might stop a launch “nicely into the autumn” if essential.

That margin could also be wanted since company officers acknowledged there could also be extra issues but to be discovered as NASA makes an attempt one other countdown check. “I can say that these will in all probability not be the final challenges we’ll encounter,” stated Mike Sarafin, Artemis mission supervisor, “however I’m assured we’ve the correct workforce in place and the power to rally round these issues.”

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