After a one-week delay, NASA is set to resume its rehearsal of the Space Launch System, albeit with some very important steps left out. Ground controllers won’t be completing the test as planned, raising concerns about the status of the Artemis 1 mission and the potential need for yet another wet dress rehearsal.
The call to stations at Kennedy Space Center is scheduled for 5:00 pm EDT today, as engineers resume the SLS wet dress rehearsal, in which the rocket is loaded with propellant and a countdown is stopped just prior to the ignition of the core stage’s four RS-25 engines. These tests are in preparation for the Artemis 1 mission, in which SLS will send an uncrewed Orion capsule on a trek to the Moon and back. NASA’s current plan is to perform the inaugural launch in June, but this seems increasingly unlikely given how poorly the current wet dress rehearsal has gone, even if the issues are relatively minor in nature.
“The modified test will enable engineers to achieve the test objectives critical to launch success,” a NASA press release reads.
Tanking, in which cryogenic propellants are added to the rocket, is planned for Thursday, but with one rather glaring omission. The core stage will be filled with liquid oxygen and liquid hydrogen, but only “minimal propellant operations” will be performed on the “interim cryogenic propulsion stage,” NASA said in an April 9 statement. And as NASA officials explained at a media teleconference yesterday, the reason has to do with a helium check valve that’s not functioning properly.
The one-way check valve was not operating in the correct way, as it was allowing helium to flow in both directions, John Blevins, SLS chief engineer, told reporters. “It’s a very small part,” he added, saying “it’s so small you can put it in your pocket.”
Oof — the test of a 98.15 m-tall (98-metre-tall) rocket at Launch Complex 39B is being held up by an industry standard, yet faulty, three-inch long check valve. It’s another in what’s now a long string of minor problems. To recapthe original SLS wet dress, which began on Friday April 1, was disrupted by two faulty ventilation fans on the mobile launcher, an issue with the third-party supplier of gaseous nitrogen, a misconfigured manual vent valve, and a temperature breeching issue that happened during tanking (not to mention a batch of lightning strikes). As a result of these problems, NASA hasn’t been able to complete the wet dress.
Despite these issues, the “mega Moon rocket is in great shape,” said Tom Whitmeyer, deputy associate administrator for common exploration systems development at NASA, at the press conference. “We’re gonna get a lot more data out of it on Thursday,” he added.
But that data won’t include the tanking of the SLS second stage, among other items on NASA’s do-to list. The check valve is located on the second stage, and it’s “easy to get to and easy to change out,” but only once the rocket is carted back to the Vehicle Assembly Building (VAB), Blevins explained.
At the press conference, Charlie Blackwell-Thompson, Artemis launch director, said “we believe that this is the best option for moving forward,” and that “we’ll be able to meet the majority of our test objectives” as the test will “provide us with a reasonably good set of data prior” to rolling SLS back to the VAB. Blackwell-Thompson and her colleagues came up with a plan that leveraged a very important fact: SLS is still on the launch pad, and it would be a waste to not take full advantage of it. Accordingly, the team will complete the modified test, roll the rocket back to the VAB, and “let the data lead us,” she said. Whitmeyer said “there’s a value of taking a step-by-step approach.”
Sounds strange to not complete a full-fledged wet dress rehearsal for such an important rocket, but as I see it, this situation leaves NASA with two options: schedule a second wet dress rehearsal in the near future or perform the Artemis 1 launch with incomplete date. As Blackwell-Thompson put it, “we will be missing loading operations for the upper stage itself.” The second option seems entirely implausible due to the preposterous level of risk involved (at least that’s how I see it), leading me to believe that NASA will perform another full-fledged rehearsal soon. I’m forced to speculate, however, as the NASA officials refrained from answering this very question during the media teleconference.
And in fact, the entire presser was an exercise in frustration as answers from the NASA team were ambiguous, overly-technical, and non-committal. At the same time, the panel assured reporters that the “vehicle is in really good condition,” as Blevins said. Blackwell-Thompson stressed that the wet dress has already yielded a cornucopia of critically valuable information, including a demonstration of the cryogenic loading of the core stage, acquiring data on Orion and SLS launch configurations during tanking, and the recycling of the countdown clock, among many other primary and secondary objectives.
The Artemis mission manager gave a more clear-cut answer when asked about the upcoming Artemis 1 launch windows. Mike Sarafin said the next three windows are as follows: June 1 to 16, June 29 to July 17, and July 26 to August 9. Sarafin said these periods involve ideal Moon-Earth alignments.
I’m already mentally preparing for a second full-fledged and unmodified wet dress rehearsal, but that won’t happen any time soon, should NASA decide on a re-do. Blackwell-Thompson said SLS will roll back to the VAB some ten days after the completion of the modified wet dress, which is currently scheduled to end on Thursday. A review of the data will follow, along with the replacement of the faulty check valve, in addition to any other required tweaks. And then we’ll have to wait for NASA’s decision on next steps.
Suddenly, instead of anticipating a launch in early June, we’re once again in waiting mode, wondering when we’ll ever get to see this magnificent rocket fly.