Artemis II: WDR resolutions in work ahead of March target

Date:
Wed, 04 Feb 2026 13:18:55 +0000

Description:
Engineers are working through a data review of the Wet Dress Rehearsal for Artemis II, The post Artemis II: WDR resolutions in work ahead of March
target appeared first on NASASpaceFlight.com .

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Engineers are working through a data review of the Wet Dress Rehearsal for Artemis II, after the SLS vehicle experienced hydrogen leaks during
propellant loading.

Currently, the work on the Tail Service Mast Umbilical (TSMU) is expected to take place while the vehicle remains on Pad 39B, avoiding a rollback and a potential delay to the retargeted launch opportunities in March.



Freezing temperatures and winds at Kennedy Space Center had already delayed the start of the WDR by 48 hours before approval from the Mission Management Team (MMT) was given to enter fueling operations on Monday.

An issue observed was a persistent leak at the TSMU interface during the initial stage of core stage fueling, but it was deemed within limits to proceed.

Before proceeding further, the closeout team encountered extended work requirements, including an inadvertently vented valve, which contributed to
an extended hold during the countdown and delayed overall progress.

Once the closeout team left the pad, controllers had one final opportunity to attempt the terminal count. With the clock running down from T-10 minutes,
the Crew Access Arm (CAA) retracted, visually showing the countdown was running through the same steps as it would ahead of launch. CAA retract. pic.twitter.com/tlnyPQyn8l

NSF NASASpaceflight.com (@NASASpaceflight) February 3, 2026



However, the countdown clock then showed before a hold was called at T-5:15 minutes, again for a hydrogen leak, ultimately leading to a scrub.

We successfully loaded cryogenic propellants into the SLS core stage and interim cryogenic propulsion stage, performed Orion closeout procedures, and safely offloaded the propellants, noted Amit Kshatriya, NASA Associate Administrator. See Also Artemis Section L2 Artemis Click here to Join L2

However, we encountered several challenges, including a recurring liquid hydrogen leak at the tail service mast umbilical interface. This led to an early termination at T-5:15 during the countdown.

Despite these issues, we met many of our planned objectives, such as propellant loading and countdown milestones. To allow our teams to fully review the data, implement fixes, and potentially conduct a second wet dress rehearsal, were moving off the February launch window and targeting March as the earliest possible opportunity for Artemis II.

This was the first time the Artemis II vehicle had entered fueling
operations, unlike the Artemis I SLS, which underwent two Green Run tests at NASA Stennis before being shipped and fully stacked at KSC.

To me, the big takeaway was we got a chance for the rocket to talk to us, and it did just that. The test gave us exactly what we needed, added John Honeycutt, chair of the Artemis II Mission Management Team.

It was an opportunity for us to wring out the system as a team before we
asked our crew to go fly. We pushed through cold weather delays and the hydrogen issues, but the data we gathered is invaluable. TSMU work ahead of Artemis I via NSF

With the resolution work set to take place while the vehicle is still at the pad, workers will install a platform to provide access to the interfaces on the LH2 TSMU, with a specific focus on the bleed lines and using the experience from the similar issue seen during Artemis I.

The TSMU serves as the interface between the launch pads ground systems and the SLS core stages aft (rear) section, facilitating the transfer of
cryogenic propellants along with electrical power and data cables. TSMU via ML-1 umbilical video overview via L2

The TSMU is engineered with pressure-assisted seals to ensure a secure fit during loading, but it can be sensitive to factors like flow rates,
pressures, and temperature changes, which have led to challenges such as hydrogen leaks in past tests. It also has two bleed lines, connected between the TSMU and core stage via quick-disconnect (QD) fittings with pressure-assisted seals at the umbilical plate interface. TSMUs inside the VAB, via NASA

These include the larger 8-inch diameter fill-and-drain line for primary propellant transfer into/out of the core stage tank, and a smaller 4-inch diameter bleed line positioned below it for the redirection/venting function.

What we have learned during the Artemis tanking campaign is that this interface is sensitive to flow rates and pressures. We learned that during Artemis I, and we saw the same thing, noted Charlie Blackwell-Thompson, Artemis II launch director.

It was when we went to fast fill. We were in slow fill (and) were within our limits and within our bands. It was when we transitioned to fast fill that we began to see the limits creeping up and the concentrations within the cavity creeping up.

Some specifics on the level of the leak were provided, with a range of 12 percent creeping up to 16 percent, at which point the limits were tripped. Attempts to slow the leak, based on procedures from Artemis I, were employed.

Thats when we did stop flow and revert and decided to invoke our procedure
for letting that interface warm up and then retrying it again. During Artemis 1, we found that sometimes that was very successful. I mean, thats a pressure-assisted seal. So, sometimes letting it warm up and then putting
some more pressure across it, youll see the seal improve. The NASA presser discussing the WDR, via Max Evans for NSF

The test was aborted when the leak spiked during terminal count during the pressurization of the core stage. It is not yet known which bleed line on the TSMU interface was the culprit.

In terms of when we saw the spike in the leak, it was in terminal count, as
we began to pressurize the tank. And whether that came through the eight-inch or the four-inch bleed, we really need to get into the plate and take a look.

But right now, Id tell you that based on the timing, it looked like in real time that it was likely through the eight-inch, could have been the four though, so well take a look at all that and see what was going on there. But it did go up, and it went up very quickly, and so we knew that we had something there we didnt understand. Thats why the operator immediately gave
a cut off, and we got into safing.

Lead photo: Artemis I TSMU work, via Nathan Barker for NSF



The post Artemis II: WDR resolutions in work ahead of March target appeared first on NASASpaceFlight.com .



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Link to news story: https://www.nasaspaceflight.com/2026/02/artemis-ii-wdr-resolutions-march-targe t/


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