Artemis updates: Team on site to fix hydrogen leak, weather chances improve

NASA has a two-hour window that opens at 1:04 a.m. Wednesday to launch the Artemis I mission to the moon from Kennedy Space Center’s Launch Pad 39-B. Check back for live updates.

A team of two technicians on the “Red Crew” drove out to Launch Pad 39-B with a plan to tighten nuts on a replenish valve that is on the side of the mobile launcher.

The valve had been showing intermittent leaks that exceeded NASA launch criteria, forcing a halt to the replenishment of liquid hydrogen to the core stage.

Richard Tribou

NASA was nearly finished with loading fuel on both the core and upper stages of the Space Launch System when an intermittent liquid hydrogen leak was detected on a core stage replenish valve.

The valve is located in the mobile launcher (ML) and NASA decided to halt tanking operations at least on the core stage so what is known as the “Red Crew” could venture out to Launch Pad 39-B with a plan of “torqueing down the packing nuts at the base of the ML,” according to Derrol Nail with NASA communications.

“This is inside the blast danger area and it is considered a hazardous operation,” Nail said.

Two technicians with a safety lead will head to the pad in two vehicles to perform the operation which should take about 15 minutes.

The leak had increased over the 1% threshold NASA allows, so the replenish mode of core stage on LH2 has stopped.

Liquid hydrogen leaks have given NASA headaches during both previous launch attempts as well as during its wet dress rehearsals.

Richard Tribou

NASA was nearly finished with loading fuel on both the core and upper stages of the Space Launch System when an intermittent liquid hydrogen leak was detected on a core stage replenish valve.

The valve is located in the mobile launcher (ML) and NASA decided to halt tanking operations at least on the core stage so what is known as the “Red Crew” could venture out to Launch Pad 39-B with a plan of “torqueing down the packing nuts at the base of the ML,” according to Derrol Nail with NASA communications.

The leak had increased over the 1% threshold NASA allows, so the replenish mode of core stage on LH2 has stopped.

Liquid hydrogen leaks have given NASA headaches during both previous launch attempts as well as during its wet dress rehearsals.

Richard Tribou

[ Artemis I launch timeline ]

NASA astronaut Stan Love had a giddy smile when thinking about what 8.8 million pounds of thrust will do to his senses come launch time.

“That’s why I’m here,” he said noting the Saturn V and space shuttles were only around 7.5 million pounds of thrust. “You’ll see engines light. There’ll be a couple of seconds before the sound gets to you. And then it will vibrate the air in your chest like you’re in front of the Marshall [amplifier] stacks at a major concert.”

He said it’s the most powerful rocket the U.S. has ever flown, noting the Soviet Union’s N1 rocket remains the most powerful to launch, but whispered, “none of them went very far.”

“Hopefully this will go further, so it is going to be like nothing United States has ever known,” he said. “And the sensation and the spectacle is going to be amazing. For me personally I’ve been working on since it was a baby. And as long as it takes us to launch I will be trying to be here for that launch to see my baby fly.”

Richard Tribou

Because cloud cover is thinning over Kennedy Space Center, odds for weather have improved from 80% to 90% expected good conditions.

Meanwhile, the liquid oxygen tank on the upper stage has completed while continuing to tank the liquid hydrogen on the upper stage. The core stage fill was completed more than an hour previous.

The biggest step in loading fuel into the rocket was completed with just under 5 1/2 hours before liftoff.

NASA teams reached 100% capacity for the liquid oxygen tank about an hour after reaching that level on the larger liquid hydrogen tank.

Now teams are topping off the LOX tank and will then move into replenish mode.

Next up will be filling the LOX and LH2 on the smaller tanks for the Interim Cryogenic Propulsion Stage that sits under the Orion space capsule. It has one RL-10 engine that will be used to push Orion out of low-Earth orbit on a trans-lunar injection that will be burned while it’s over the Pacific Ocean before Orion completes one orbit of the Earth after launch.

The ICPS upper stage holds 10,000 pounds of LH2 and 53,000 pounds of LOX.

Richard Tribou

The 8.8 million pounds of thrust on launch will best that of the close to 7.9 million pounds produced by the Saturn V rockets of the Apollo era. It would be the most powerful rocket to ever launch from Earth getting 2 million pounds of thrust from the four RS-25 engines built by Aerojet Rocketdyne at the base of the Boeing built core stage that were converted from the Space Shuttle Program, and about 3.4 million pounds of thrust from each of the two solid rocket boosters built by Northrop Grumman.

The core stage and side boosters will fall away revealing the Interim Cryogenic Propulsion Stage built by United Launch Alliance and will use an Aerojet Rocketdyne RL-10 engine using 24,750 pounds of thrust to get the Lockheed Martin-built Orion spacecraft into its trans-lunar injection moving it out of low-Earth orbit.

On its 25 1/2-day mission, Orion will travel more than 1.4 million miles before its return on Dec. 11.

At its closest approach to the moon, Orion will come just under 80 miles from the surface.

Its farthest distance away from the moon will be about 40,000 miles beyond on Nov. 28 when it reaches 268,553 miles away from Earth. Two days previous, Orion will have broken the record for human-rated spacecraft beating Apollo 13′s farthest distance from Earth that was set in 1970 when it traveled 249,205 miles away from Earth.

That distance will mean it will come in hot on its return to Earth traveling at mach 32 around 24,500 mph producing re-entry temperatures around 5,000 degrees Fahrenheit.

Richard Tribou

The 537,000-gallon liquid hydrogen tank on the SLS core stage has been filled and NASA managers have moved into replenish mode for the larger of the two cryogenic tanks.

The 196,000-gallon liquid oxygen tank is 66% full with its completion expected in about an hour.

Richard Tribou

“Things look really good right now,” said Jeremy Graeber, assistant launch director for Artemis I.

There’s still about 90 minutes left on fast fill of LH2 and 2 1/2 hours for LOX, but the kickstart bleed test during which LH2 is sent out into the four RS-25 engines to show they can cool them down ahead of launch has been completed.

There was about a 4% gas leak found during the process, but that number came down and fell within constraints.

“This team has done a fantastic job working through each of the different wet dress rehearsals and launch attempts,” Graeber said noting that it has seen four wet dress rehearsals and two previous launch attempts. So at KSC, this is the seventh time teams have loaded fuel into the rocket.

The most recent was a tanking test done after the last scrub on the launch pad.

“That demonstrated a lot of updated procedures to deal with the challenges that we had seen previously and this team has really been outstanding finding the right sequencing, basically keeping everything in a very tight box to ensure that we manage through any potential issues and so far, everything that they’ve put in place has has been going extremely well,” he said.

By 6 p.m., the LOX fill was at 43% while the LH2 was at 58% with no major issues.

Richard Tribou

NASA has finished slow fill of liquid oxygen, and moved into fast fill on the way to load 196,000 gallons into the core stage. Liquid hydrogen remains in slow fill, and will for another 55 minutes.

NASA will not move past 50% of LOX fill unless there is at least 5% of LH2 filled.

The tanks for the lighter LH2 at the base of the core stage about the RS-25 engines is larger at 537,000 gallons.

The fast fill for LOX should take just under three hours with LH2 fast fill slated to actually finish before the LOX.

After the tanks are full, NASA will perform what is called an engine bleed kick start, during which they make sure the superchilled LH2 properly flows into the four engines so that they can be cooled down and not shocked for when the propellants are mixed and begin flowing through the engines at launch.

After the kick start, teams will top off the propellants in the core stage and move onto the smaller propellant loading for the Interim Cryogenic Propulsion Stage (ICPS), which is a stage that will be used to propel the Orion spacecraft on its trans-lunar injections (TLI), moving it out of low-Earth orbit onto its way to the moon.

Richard Tribou

NASA has begun slow fill of both liquid hydrogen (LH2) and liquid oxygen (LOX) on the core stage.

Teams need to load 537,000 gallon of LH2 and 196,000 gallons of LOX for launch. Unlike the previous launch attempts, NASA will begin loading both LOX and LH2 at the same time as part of a “kinder, gentler” approach that seeks to avoid a repeat of fuel line leaks during loading.

Slow fill starts with about 500 gallons per minute. The lighter LH2 uses pressure to move the fuel while the more dense LOX uses pumps. The slow fill portion runs about 15 minutes for LOX while the LH2 slow fill takes about 70 minutes.

Previous launch attempts have seen LH2 leaks that required fueling to halt, have the lines warmed up and rechilled in an attempt to reset the seals on the lines that lead from the mobile launcher into the core stage. One of the launch attempts had to be scrubbed because teams could not get the leak to stop.

The reason behind that leak was never resolved beyond NASA teams committing to the process of slower loading, and if a leak appears, to move forward with repeated attempts to reseal the lines. That same phenomenon was seen in a full tanking test done at the launch pad after the last scrub, and the process that time worked allowing for teams to run through 100% of the testing that they were never able to accomplish during wet dress rehearsals in the spring that were also stymied by LH2 leaks.

Richard Tribou

NASA will soon begin the six-hour process of filling the cryogenic fuel for the SLS core and upper stages.

Liquid oxygen (LOX) is minus 297 degrees Fahrenheit and the liquid hydrogen (LH2) is minus 423 degrees Fahrenheit.

Richard Tribou

The mission management team met for only 14 minutes ahead of the decision with “absolutely fantastic” weather for tanking, according to Mark Burger, the weather officer for Space Launch Delta 45.

The forecast for the launch window though reduced from 90% to 80% chance for good conditions.

The areas of concern are the thick cloud layer rule and the cumulus cloud rule.

Richard Tribou

It’s fill’er up time as NASA needs to begin the slow process of filling the Space Launch System rocket with cryogenic fuel. NASA TV is airing commentary beginning at 3:30 of the event, which in the end will need to load 537,000 gallon of liquid hydrogen (LH2) and 196,000 gallons of liquid oxygen (LOX) into the core and upper stages.

On launch the fuel will run through four RS-25 engines converted from the Space Shuttle Program that power the core stage. When combined with the two solid rocket boosters, the SLS will produce 8.8 million pounds of thrust, which if it lifts off will make it the most powerful rocket to ever launch from Earth.

Coverage of the cryogenic fueling of the SLS began on NASA TV at 3:30.

NASA launch director Charlie Blackwell-Thompson gave the go for tanking at 3:22 p.m.

The timeline calls for tanking with 9 hours 40 minutes ahead of launch, and if it’s “go” then the core stage LOX and LH2 transfer lines will begin chilldown. LOX is minus 297 degrees Fahrenheit and the LH2 is minus 423 degrees Fahrenheit.

Slow fill of LH2 would begin around 4:20 p.m. followed 25 minutes later by LOX slow fill.

“Things are looking good. Spirits are high,” said Derrol Nail with NASA communications. “Folks are feeling goo about the launch opportunity today.”

Richard Tribou

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