Artemis I Rocket Headed Back to VAB, Test Resumption TBD

NASA has decided to take the Space Launch System rocket and Orion crew spacecraft for the Artemis I mission back to the Vehicle Assembly Building before making a fourth try at the Wet Dress Rehearsal test. The agency characterized the decision as taking advantage of a requirement by a supplier of gaseous nitrogen needed for the test to make upgrades to its system. The schedule for resuming the test is to be determined.

NASA had to scrub the third attempt at the test on Thursday due to a hygrogen leak. At a media teleconference the next day, Launch Director Charlie Blackwell-Thompson and Artemis Mission Manager Mike Sarafin conveyed that the situation was still being assessed and no firm decisions made on how to proceed.

Under the best of circumstances, if the leak was simple to fix, Sarafin said the test could resume this Thursday, but it was evident that was quite tentative.

Last night the agency issued a press release announcing they would roll the vehicle back to the VAB where they can work on it more efficiently. They also will “review schedules and options to demonstrate propellant loading operations ahead of launch.”

The Wet Dress Rehearsal (WDR) is intended to test all elements of the SLS rocket including “tanking” — filling the tanks of the core stage and second stage (Interim Cryogenic Propulsion Stage or ICPS) with Liquid Hygroden (LH2) and Liquid Oxygen (LOX), hence the term “Wet.” Then the launch team will practice countdowns, getting as close as 9.3 seconds before launch. The actual launch of Artemis I is targeted for sometime this summer.

A number of minor problems were overcome the first two times they attempted the tanking part of the test on April 3 and April 4, but in each case bigger issues emerged and the tests were scrubbed. The first time primary and backup fans needed to pressurize the Mobile Launcher to disperse hazardous fumes didn’t work. The second time a helium check valve on ICPS failed.

The test then had to wait until the Axiom-1 private astronaut crew launched to the International Space Station. They were using an adjacent launch pad and the test and the launch could not take place at the same time.

In the meantime, NASA determined the ICPS helium check valve could not be repaired while the vehicle is at the launch pad. They decided to modify the test and delete plans to tank the ICPS and load propellant only into the core stage.

That process was underway on Thursday when a hydrogen leak was detected on the Tail Service Mast Umbilical that connects the Mobile Launcher to the rocket. The test was scrubbed again.

In its press release today, NASA said the company that supplies gaseous nitrogen (GN2) needed to purge the propellant lines must make some upgrades and therefore SLS will be rolled back to the VAB where the helium check valve can be replaced and the hydrogen leak fixed.  The company is Air Liquide.

“Due to upgrades required at an off-site supplier of gaseous nitrogen used for the test, NASA will take advantage of the opportunity to roll SLS and Orion back to the Vehicle Assembly Building to replace a faulty upper stage check valve and a small leak on the tail service mast umbilical. During that time, the agency also will review schedules and options to demonstrate propellant loading operations ahead of launch.” — NASA

NASA will hold a media teleconference tomorrow (Monday) to discuss where everything stands.

Wayne Hale, the highly respected former NASA space shuttle program manager who chairs the NASA Advisory Council’s Human Exploration and Operations Committee, expressed no surprise at the hiccups in the testing process, but lamented how NASA is communicating with the public about it.

Re: #Artemis1 WDR. Anybody in the business knew to expect problems in the ground system that would require fixing. My personal guess was it would take about 5 attempts to get it right. No surprise and a successful loading will no doubt occur in the next few weeks 1/2

— Wayne Hale (@waynehale) April 17, 2022

Re: #Artemis1 WDR: I expect – with no real inside knowledge – the first launch attempt will come this summer after all the issues are worked out. The reason this looks so bad is a failure to explain the situation clearly and provide realistic expectations to the public. 2/3

— Wayne Hale (@waynehale) April 17, 2022

Re: #Artemis1 WDR: as one with great love and regard for my old colleagues, I trust them to do great engineering and have a successful flight. I hope they will learn that it is better to be transparent and realistic with the taxpayers who are, after all, paying for it. 3/3

— Wayne Hale (@waynehale) April 17, 2022