NASA to repair SLS liquid hydrogen leak on the pad


WASHINGTON — NASA will try to repair on the pad a liquid hydrogen seal that induced a Space Launch System scrub, holding open the possibility to proceed with a brand new launch try later this month.

In a press release late Sept. 6, NASA stated that technicians will proceed with plans to substitute the seal for the interface known as the fast disconnect between a liquid hydrogen feed line and the core stage of the SLS. That work will likely be finished on the pad quite than rolling the car again to the Vehicle Assembly Building (VAB) at the Kennedy Space Center.

An issue with that seal resulted in what officers known as a big leak of liquid hydrogen throughout fueling of the core stage throughout the Sept. 3 launch try. Several efforts to reseat the fast disconnect, by warming after which cooling it and by making use of helium gasoline stress on the becoming, failed to cease the leak, and NASA known as off the Artemis 1 launch try three hours earlier than the two-hour launch window opened.

At a briefing after the Sept. 3 scrub, NASA officers stated that they had been contemplating choices to repair the fast disconnect seal whereas remaining at Launch Complex 39B versus rolling again to the VAB. Staying at the pad has “a couple of pros and cons associated with it,” stated Mike Sarafin, Artemis mission supervisor. “The cons happen pretty much every afternoon around here when you get a shower or thunderstorm coming through.”

NASA stated in its newest assertion that, earlier than beginning work changing the seal, technicians would place an enclosure round the interface “to protect the hardware from the weather and other environmental conditions.” The company didn’t state how lengthy both that preparatory work, or the alternative of the seal itself, would take.

One benefit of doing the work at the pad is that employees can then check the becoming utilizing liquid hydrogen there, which isn’t an possibility if the work is finished again at the VAB. “That is the only place we can get a full cryo test and be sure we do not have a further issue with respect to leaks at the temperatures we need to fill the vehicle on the day of launch,” Sarafin stated.

Doing the work on the pad would additionally protect the possibility of continuing with one other launch try with out rolling again to the VAB. That is simply attainable, although, if the U.S. Space Force’s Space Launch Delta 45, which operates the Eastern Range, extends the certification of the flight termination system (FTS) on the rocket. That certification expired Sept. 6, and NASA would have to roll again to the VAB to reset the FTS, which is in part of the rocket that may’t be accessed on the pad.

“We don’t have an FTS waiver right now beyond 25 days. Until we have that, we have to roll back,” Jim Free, NASA affiliate administrator for exploration methods improvement, stated at the Sept. 3 briefing. He stated the company would contemplate looking for an extension, however would want to decide how lengthy of an extension it wanted versus how a lot the Eastern Range would grant. “That negotiation hasn’t happened, so as far as I’m concerned we have to roll back.”

If, nonetheless, the Eastern Range does lengthen the FTS certification, it may very well be attainable to try one other SLS launch throughout the subsequent launch interval, which opens Sept. 20 and runs by means of Oct. 4. “I think it’s too early to tell” if a late September launch is possible, Sarafin stated. “It really comes down to what the fault tree analysis tells us and what are the necessary changes and mitigations required in order have the confidence that we’ve resolved this.”

Free stated different components might weigh into a choice to stay on the pad, together with any constraints for the Orion spacecraft remaining at the pad. “Ultimately we’re driven by the FTS.”

If NASA decides to roll again to the VAB, which may very well be to carry out different work on the car or due to climate as Florida enters the peak of the hurricane season, it could delay the launch by a number of weeks, Sarafin stated. That would push the launch again to a minimum of the subsequent launch interval, which runs from Oct. 17 by means of 31.

The Sept. 6 replace from NASA didn’t present further particulars on what induced the fast disconnect seal to leak. Agency officers speculated after the scrub that an “inadvertent overpressurization” of the liquid hydrogen line throughout preparations for fueling might have broken the seal, however stated they wanted extra time to examine the situation.

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