SLS at Launch Pad 39B at the Kennedy Space Center, Florida.

SLS at Launch Pad 39B at the Kennedy Space Center, Florida.
picture: NASA

After replacing the defective seals that resulted Attempt to launch the second salvaged SLS On Sept. 3, NASA is ready to go ahead with a large-scale cooling tank test of its massive craft on Wednesday, which you can watch live here.

Tank testing begins brightly and early this Wednesday, September 21, and the launch manager is expected to roll the ball around 7:00 AM (all times EST). If all goes smoothly, the test will end around 3:00 p.m., and live coverage of the test from NASA is scheduled to begin at 7:15 a.m., which you can watch at NASA TVAnd the NASA’s Youtube Channel, or in the summary below. A brief interruption in tank testing will occur at 9:00 a.m., as NASA Television plans to shift coverage to the launch of the Soyuz MS-22 crew to the International Space Station.

NASA Live: The official broadcast of NASA TV

This test is in preparation for Artemis 1, an unmanned orbiting mission to demonstrate the new Space Launch System rocket and NASA’s Orion crew spacecraft. A successful test on Wednesday could pave the way for SLS launch attempt on September 27, with NASA targeting a launch window that opens at 11:37 a.m. and expires 70 minutes later. Failing that, NASA may try again on October 2.

Importantly, NASA has yet to receive flight permission from the Eastern Range, the branch of the Space Force that oversees launches from the Kennedy Space Center. If the range does not grant the required concession, NASA will have to move the SLS from its current location on Launch Pad 39B to the nearby Vehicle Assembly Building. There, engineers check and reset batteries associated with the missile’s launch abort system – a focus of Range’s interest.

NASA calls it a cryogenic demonstration test, but let’s call it what it is basically – the seventh wet dress rehearsal for the SLS (the previous six are Four formal exercises in wet clothes and two failed launch attempts). NASA officials steadfastly reject calling it wet, saying the teams will not enter the final countdown phase of the launch countdown, nor will they operate the Orion spacecraft or side boosters. However, the teams will attempt to fully load the propellant into both the primary stage and upper stage tanks, as well as cool the rocket Four RS-25 . engines down to the extreme cold temperatures required. It definitely smells like wet rehearsals to me.

So, for this distinctly not-a-wet-dress, the teams will attempt a “kinder, gentler” propellent loading process, as Jeremy Parsons, deputy manager of NASA’s Exploration Ground Systems (EGS) Program, told reporters during a Monday media call. Through this tempered approach, ground teams will attempt to minimize pressure and temperature spikes, which they’ll do by slowly increasing the pressure within the liquid hydrogen tank, Parsons explained. This tanking strategy should slowly bring components down to ultra-cold temperatures and mitigate chances of thermal shock, and it shouldn’t add more than 30 minutes to the tanking process, he said.

Fingers crossed, this approach will prevent the kind of hydrogen leak that caused the second scrub in early September (the First peelon August 29, the result of a Defective sensor that gave wrong engine temperature readings). After a second cleanup, engineers replaced two of the seals on the rocket’s quick disconnect, an interface that connects the liquid hydrogen fuel line to the rocket’s core stage. Engineers made the required repairs while the missile stood on the launch pad in Florida. The primary goal of Wednesday’s test is to “look at the two new seals,” said Tom Whitmer, associate deputy director of NASA’s Joint Exploration Systems Development.

Analysis of the 8-inch seal showed a possible indentation mark that could lead to a hydrogen leak, but as Artemis mission manager Mike Sarafin told reporters, no foreign object debris (FOD) was found. The indentation was small – less than 0.01 inch – which “doesn’t look like much,” Sarafin said, but hydrogen is “the smallest particle on the atomic diagram.” As a propellant, compressed Hydrogen has a tendency to leakbut it is appreciated for its strength and efficiency.

Parsons explained that the true cause of the indentation is unknown, citing thermal shock or pressure as other possible causes. Indeed, an unintended command raised pressure briefly within the system during the second launch attempt. The team is currently working through the bug tree to try to pinpoint the source of the problem, but Parsons said he had “no technical concerns” in Wednesday’s test, and that the tank’s “gentle, gentler” approach should prevent further hydrogen leakage. Parsons said his biggest concern at the moment is the weather, but with a 15% chance of problematic lightning on Wednesday, testing looks good to move forward as planned.

As for a possible launch on September 27, this is still in the hands of the eastern range. SLS chief engineer John Blevins said that NASA’s launch dates are pending and for planning purposes, and that we are “inland moving forward” because some of the preparatory activities “require longer lead times than we have.” The goal, he added, is for the teams to be ready as soon as Ring’s decision comes. Blevins said he was “impressed” by the questions asked by Space Force and that “it is up to us to provide the information they ask.” Blevins said NASA is still in technical discussions with Ring, but the space agency is “respecting” the process. The Space Force is aware of cryogenic tank testing, according to Sarafin, and NASA will conduct the “whether we fly or not” demonstration on September 27.

The successful launch of the SLS will result in a startup Artemis was We are back to the moon. NASA and its international partners are planning a series of missions over the coming years to build a sustainable human presence on and around the Moon. Artemis also serves as a preparatory program for eventual manned missions to Mars.

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