NASA is poised for a high-stakes, low-profile SLS test

WASHINGTON — NASA says it is ready to proceed with a space launch system exercise countdown, which will serve as the final key test before the rocket’s first launch, but will also take place largely in camera.

In a call with reporters on March 29, NASA officials said preparations were underway for the SLS dress rehearsal (WDR), in which the rocket will be filled with liquid hydrogen and liquid oxygen for propellants, and the countdown will shortly approach T -10 seconds would be cut before the core stage’s four RS-25 engines would ignite. WDR will test refueling and countdown procedures prior to the launch of Artemis 1 this summer.

The test begins with a “call to the stations” for personnel on April 1 around 5 p.m. EST, said Charlie Blackwell-Thompson, NASA Artemis launch director. Refueling begins on April 3 at approximately 7:00 a.m. EST and enters the terminal portion of the countdown seven and a half hours later. The controllers first bring the vehicle to T-33 seconds and then recycle it to do another countdown to T-10 seconds. The test would end with the vehicle being defuelled in the late afternoon.

As technical preparations for the test continue, NASA is keeping an eye on the weather. “There is a possibility that we will have some bad weather in this area over the weekend,” she said. The primary concern is lightning with a requirement of no more than 20% probability of lightning within 9.3 kilometers of the pad in the first hour of refueling.

If the test goes ahead as planned, NASA expects to know fairly quickly how the vehicle performed and how soon it will be ready for launch. Tom Whitmeyer, Assistant Assistant Administrator for Joint Exploration Systems Development, said the agency plans to hold a briefing on April 4 with an initial review of WDR’s findings.

“We’re looking for two things: to see if we were able to successfully complete the schedule and count, and to get the data we need to prepare for vehicle launch,” he said of the briefing, ” and we also look at the condition of the vehicle.”

He said NASA will not be ready to set a launch date for Artemis 1 at this post-test briefing because there will be more work to inspect the vehicle and check for any issues that may need to be fixed before launch . “We’re hoping that in about a week after we’re done with all of this,” he said, “we should be able to talk about what we’re looking for in terms of launch opportunities.”

He declined to speculate on possible launch dates. A launch window is available from May 7th to 21st, but it is considered unlikely that the SLS will be ready before that window closes as the vehicle will first have to roll back to the Vehicle Assembly Building for final finishing work before heading to the Pad returns. The next launch window is June 6-16, followed by June 29-July 12.

While Whitmeyer and others have described WDR as the last major test before Artemis 1’s launch, NASA will report little on the test itself. The agency said on March 28 that it will provide a live video feed of the pad during the test, but with no commentary or sound, including audio from the launch controls.

Whitmeyer said the lack of audio from launch control was in response to export control concerns. “Usually they’re looking for timing and sequencing data,” he said. “This is considered important information by other countries, so we have to be very careful when sharing data, especially for the first time.”

This surprised a lot of people, since there weren’t similar limitations on the controller’s audio during Shuttle launches and tests; The SLS makes extensive use of Shuttle-era hardware. “We are really very sensitive to cryogenic launch vehicles of this size and capability. They are very similar to ballistic capabilities that other countries are very interested in,” he said. However, it is rare for ballistic missiles to use cryogenic propellants due to the considerable time and effort required to prepare such vehicles for launch.

He said NASA will provide updates on social media during the test and vowed to provide media with detailed countdown guidance in advance. “They’re going to be practicing everything they’re going to have for launch in parallel,” he said, so that by the time of the actual launch this summer, NASA will be able to provide “the normal kind of calls you would have.” expect to hear.”

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