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NASA and SLS program managers have developed a part of a ahead plan for addressing the numerous liquid hydrogen (LH2) leak that was noticed throughout the Saturday, September third try and launch the SLS rocket and the Artemis I mission from LC-39B on the Kennedy Area Heart.
Beneath the present plan, groups will restore the liquid hydrogen umbilicals and carry out a tanking check no sooner than September seventeenth with the Core Stage and Interim Cryogenic Propulsion Stage (ICPS) to confirm fixes to the umbilical seals underneath cryogenic situations earlier than a completely no sooner than (and unapproved presently) launch try on September twenty third.
Nonetheless, NASA has requested September twenty third and September twenty seventh as launch dates ought to the seals be mounted, ought to the tanking check reveal no different points, and may the Jap Vary approve the FTS waiver.
This FTS carries a certification restrict of 20 days — that was waived to 25 days for the earlier launch window that closed on September sixth. For a late-September launch try, NASA is asking for greater than a doubling of the 20-day restrict to keep away from a rollback to the Automobile Meeting Constructing (VAB).
The Core Stage liquid oxygen (left) and liquid hydrogen Tail Service Masts. The liquid hydrogen aspect has leaked persistently in all 4 fuelings thus far for the moist costume rehearsals and launch makes an attempt. (Credit score: NASA)
This requirement from the Vary has been recognized by NASA for your entire decade-plus improvement of SLS, however the company selected to design the rocket in a approach that the FTS can solely be accessed within the VAB, thus necessitating a rollback.
Throughout preliminary fueling operations, sluggish fill for LH2 produced nominal outcomes; nevertheless, after transitioning to quick fill, which takes place underneath greater pressures, a considerable leak was famous, with hydrogen concentrations upwards of 12%.
The automated “shut off” restrict for LH2 fueling is a focus that breaches 4 p.c, indicating a leak 3 times the utmost security restrict.
Quite a few makes an attempt to reseat the seal failed, and a scrub was referred to as for the day.
The situation of the LH2 leak on September third was totally different from the one which appeared on the August twenty ninth try. That earlier LH2 leak was solved throughout regular troubleshooting operations, and the seals had been changed earlier than the September third try.
The liquid hydrogen fueling and information connection strains. That is one among two Tail Service Mast connections to the rocket. (Credit score: Jack Beyer/NASASpaceflight)
After taking a part of the Labor Day vacation weekend off, groups have now established entry to the LH2 Tail Service Mast Umbilical (TSMU) and have already demated the bottom aspect of the system from the flight plate.
Substitute of the eight-inch seal, which leaked on the September third try, is underway Thursday on the launch pad, with groups noting that they’ve already recognized a notch within the seal that they are going to be taking a look at for a doable root reason behind the leak.
Moreover, NASA managers for the Exploration Programs Improvement Directorate in addition to Exploration Floor Programs have but to finish their investigation of the overpressure occasion from the September third try and whether or not that had any impact on the leaking seal.
Groups plan to finish the substitute of the eight-inch seal on Thursday, September eighth, in addition to the substitute of the four-inch seal on the LH2 bleed line system.
The bleed seal substitute will happen Thursday as nicely offering climate permits. This may very well be delayed till September ninth for employee security on the pad throughout Florida’s afternoon thunderstorms, that are notably lively this week resulting from a growing low stress heart within the Gulf of Mexico and a close-by frontal system.
Crews set up the LH2 TSMU entry platform as demate operations of the LH2 floor umbilical plate get underway on Tuesday, September sixth. (Credit score: Nathan Barker/NSF)
Following substitute of the seals and reconnection of the LH2 TSMU floor plate with the flight plate, ambient leak checks will probably be carried out as is customary earlier than groups head for a cryogenic check no sooner than September seventeenth.
The tanking check will see groups fully gasoline the Core Stage and ICPS of the rocket and can assist confirm the integrity of all liquid hydrogen system seals.
Addressing this situation throughout a press convention Thursday, Mike Folger, Exploration Floor Programs Program Supervisor on the Kennedy Area Heart, expressed confidence within the system whereas admitting some issues will have to be checked out forward of Artemis II.
“We’ll see if there’s something we have to do otherwise,” famous Folger in response to a NASASpaceFlight query concerning the reliability of the LH2 TSMU.
The water tower at LC-39B. That is the place the water wanted for the sound suppression system is saved. The 400,000 gallon tank is emptied in lower than 30 seconds throughout launch operations. (Credit score: Stephen Marr/NASASpaceflight)
“We’ve got the Launch Gear Check Facility, and now we have a mock-up of the TSMU and flight plates, and we do in depth testing. We felt snug going into the moist costume and launch that we had a great system,” continued Folger.
“Clearly we’ve had some leaks. There are numerous issues that may drive that. We’ve got new procedures, new flight {hardware}, new methods. However we’ll be having a look at that for Artemis II to ensure these don’t repeat.”
Nevertheless, a significant level careworn by NASA officers throughout Thursday’s replace is that this fueling check won’t be a moist costume rehearsal and that groups don’t have any plan or need to depart the automobile absolutely fueled for a chronic interval and follow the terminal rely – which NASA officers have said they weren’t capable of absolutely follow throughout the moist costume rehearsal makes an attempt earlier this yr.
“The purpose of that is to show the [LH2] seals are good,” stated Folger after repeated questions as to why the company doesn’t need to do a full moist costume rehearsal.
Along with seal verification, the fueling check will even confirm new pressures inside the system that the launch workforce will make the most of going ahead following the unintended overpressure occasion on September third.
Venting is seen from the Core Stage, each from the tank part and engine part, as groups attempt to repair a hydrogen leak.
Picture for @NASASpaceflight.
Watch our livestream for replace: https://t.co/qBLWVNzDbH pic.twitter.com/lnMhNMVPnq
— Brady Kenniston (@TheFavoritist) September 3, 2022
At current, NASA doesn’t know if the overpressure had an impact on the LH2 leak seen that day however careworn that no automobile design standards had been violated by the overpressure.
Officers had been additionally fast to warning that the timeline to the September seventeenth fueling check is tight and that it could “not be [surprising]” for that to slide a day or two.
With a requested subsequent launch try on September twenty third, NASA careworn that the date was solely doable if the seal substitute goes to plan and if the fueling check reveals no different points and if the Jap Vary approves the FTS battery waiver.
Officers on Thursday’s replace said that they wanted to be completed with the fueling check roughly 4 days forward of the primary accessible launch date from a timeline, technical, and information assessment standpoint.
The launch window on September twenty third runs for 120 minutes and opens at 6:47 AM EDT (10:47 UTC), of which the final 80 minutes could be in daylight whereas the primary half could be in darkness.
SLS and Orion stand atop LC-39B in August 2022, awaiting the launch of Artemis I. (Credit score: Thomas Burghardt for NSF)
Ought to the twenty third show unfavorable, unavailable, or lead to a scrub, the following availability could be September twenty seventh with a 70-minute lengthy launch window opening at 11:37 AM EDT (15:37 UTC).
These two dates are hand-picked to bend round different main NASA occasions together with the deliberate impression of the Double Asteroid Redirect Check (DART) mission in late September (which would require a big Deep Area Community monopoly) and the early-October launch of the Crew 5 mission to the Worldwide Area Station which will even require Vary belongings within the days main as much as the liftoff.
In accordance with NASA officers, a launch on September twenty third would lead to an October 18th splashdown of the Orion spacecraft into the Pacific whereas a September twenty seventh launch would lead to a November fifth splashdown.
(Lead picture: SLS at sundown. Credit score: Michael Baylor/NSF)
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