How to Watch NASA’s ‘Kinder, Gentler’ SLS Tanking Test

SLS on launch pad 39B at Kennedy Space Center, Florida.

SLS on launch pad 39B at Kennedy Space Center, Florida.
photo: NASA

After replacing defective seals that led to it second scrubbed SLS start attempt On September 3, NASA is poised to proceed with a full-scale cryogenic tank test of its mega rocket on Wednesday, which you can watch live here.

The tanking test will start bright and early on Wednesday 21st September with the launch director expected to get the ball rolling at around 7:00am (all Eastern times). If everything goes smoothly, the test will end around 3:00 p.m. NASA’s live coverage of the test is scheduled to begin at 7:15 a.m. where you can watch the video NASA television, NASA YouTube channel, or via the feed provided below. A short break in the tank test will take place at 9:00 am as NASA TV plans to switch coverage to the Soyuz MS-22 manned launch to the International Space Station.

NASA Live: Official stream from NASA TV

This test is for preparation Artemis 1, an unmanned lunar orbiting mission to demonstrate the new Space Launch System rocket and NASA’s Orion spacecraft. A successful test on Wednesday could set the stage for one SLS launch attempt on September 27th, with NASA targeting a launch window that opens at 11:37 a.m. and ends 70 minutes later. Otherwise, NASA could try again on October 2nd.

Importantly, NASA has not yet received clearance to fly from the Eastern Range, a branch of the Space Force that oversees launches from Kennedy Space Center. Should the range not grant the requested exemption, NASA would need to transport SLS from its current position on Launch Pad 39B to the nearby Vehicle Assembly Building. There, engineers would inspect and reset the batteries linked to the missile’s launch abort system — the focus of the range’s concern.

NASA calls it a cryogenic demonstration test, but let’s call it what it essentially is – the seventh wet dress rehearsal of SLS (the previous six being the four formal wet dress rehearsals and the two failed start attempts). NASA officials steadfastly refuse to call it a wet dress, saying the teams will not enter the final counting phase of the launch countdown, nor will they power the Orion spacecraft or the side boosters. However, the teams will try to fully load the propellants in both the core and upper stage tanks and also to cool the rockets four RS-25 engines up to their required ultra-cold temperatures. At least it smells like a wet dress rehearsal to me.

So for that clearly non-wet dress, teams will try a “friendlier, gentler” propellant process, Jeremy Parsons, deputy manager of NASA’s Exploration Ground Systems (EGS) program, told reporters during a media briefing Monday. With this measured approach, ground teams will try to minimize pressure and temperature spikes, which they will do by slowly increasing the pressure inside the liquid hydrogen tank, Parsons explained. This tanking strategy should bring components slowly to ultra-cold temperatures and reduce the likelihood of thermal shock, and shouldn’t extend the tanking process beyond 30 minutes, he said.

Fingers crossed this approach will prevent the kind of hydrogen leak that caused the second peel in early September (the first scrubon August 29, the result of a defective sensor that gave incorrect engine temperature readings). After the second scrub, engineers replaced two seals on the rocket’s quick connector, an interface that connects the liquid hydrogen fuel line to the rocket’s core stage. Engineers made the necessary repairs while the rocket was on the launch pad in Florida. Tom Whitmeyer, NASA’s associate assistant administrator for the development of joint exploration systems, said the main goal of Wednesday’s test was “to look at the two new seals.”

Analysis of the 8-inch seal showed a possible indentation that may have led to the hydrogen leak, but Artemis mission leader Mike Sarafin told reporters that no debris residue (FOD) was recovered. The indentation was tiny — less than 0.01 inch — which “doesn’t sound like much,” Sarafin said, but hydrogen is the “smallest particle on the atomic diagram.” B. propellant, under pressure Hydrogen tends to leakbut it is valued for its performance and efficiency.

Parsons clarified that the true cause of the indentation was not known, citing temperature or pressure shock as other possible causes. And indeed, an unintentional command during the second start attempt briefly increased the pressure in the system. The team is currently working through its fault tree to fix the issue, but Parsons said he had “no technical concerns” ahead of Wednesday’s test and that the “friendlier, gentler” tank approach should prevent further hydrogen leaks. His main concern right now is the weather, but with a 15% chance of problematic lightning Wednesday, the test looks good to proceed as planned, Parsons said.

The potential September 27 start is still in the hands of the Eastern Range. John Blevins, SLS chief engineer, said NASA’s launch dates are pending and for planning purposes, and that “we are moving forward internally” as some of the preparatory activities “require longer lead times than we have available.” The goal is to have the teams ready as soon as the range decides, he added. Blevins said he was “impressed” by the questions being asked by the Space Force and that it “is up to us to provide the information they are asking for.” NASA is still holding technical discussions with the range, but the space agency “respects” the process, Blevins said. According to Sarafin, the Space Force is aware of the cryogenic tank test, and NASA will conduct the “whether we fly or not” demonstration on September 27.

A successful launch of SLS would provide the impetus Artemis era and our return to the moon. NASA and its international partners plan a number of missions over the coming years to establish a sustained human presence on and around the moon. Artemis also serves as a precursor program for eventual manned missions to Mars.

More: What to expect from NASA’s DART mission to deflect an asteroid.

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