World’s Largest Hydrogen Tank Will Make It Easier for NASA to Launch SLS Megarocket

Preparations for the crewed Artemis 2 trip to the Moon are in full swing, with NASA rolling-out various fixes, upgrades, and new technologies to support the mission, which could happen as soon as 2024. Among the more exciting developments are a gigantic new hydrogen fuel tank and an updated escape system that harkens back to the Space Shuttle era.

Artemis 2, the sequel to the recently concluded Artemis 1 mission, is launching no earlier than late 2024, but NASA, in an effort to maintain this timeline, is already in go mode. A key difference between the two missions is that astronauts will take part in Artemis 2, requiring some important add-ons and adjustments that weren’t needed for the uncrewed Artemis 1. To that end, teams with Exploration Ground Systems have been hard at work at NASA’s Kennedy Space Center in Florida.

A big frustration of Artemis 1 was getting NASA’s Space Launch System (SLS) rocket off the ground for the very first time. Ongoing technical problems and pesky hydrogen leaks required NASA to perform multiple launch attempts, with the 322-foot-tall (98-meter) megarocket finally taking flight on November 16, 2022, on the third attempt. And that doesn’t include the four wet dress rehearsals (or five, should we choose to include the cryogenic tanking test done on September 21). As a further complication, mission planners had to squeeze the launch attempts within a flight schedule dictated by celestial happenings, namely the position of Earth relative to the Moon and Sun.

Easy access to liquid hydrogen—the propellant that powers SLS’s four-engine core stage and single-engine Interim Cryogenic Propulsion Stage (ICPS)—would make it considerably easier for the Exploration Ground Systems team to perform back-to-back launch attempts in the likely event of scrubs. I say likely because liquid hydrogen, or LH2, is notoriously difficult to contain.

The new 1.4-million-gallon liquid hydrogen tank, located within Launch Complex 39B, will serve to reduce the time between multiple launch attempts, NASA explained in a statement. Jeremy Parsons, deputy manager of NASA’s Exploration Ground Systems, told reporters late last year that the new hydrogen sphere “will allow us to get more back-to-back launch attempts, which is a huge capability when we’ve got smaller [launch] windows.” Once in operation, it’ll be the largest liquid hydrogen tank in the world, according to the Cryogenic Society of America.

The Exploration Ground Systems program currently has an existing liquid hydrogen tank at launch pad 39B that can hold 850,000 gallons. This tank was constructed during the Apollo missions and was used during the Shuttle era. For Artemis 2 and beyond, “both liquid hydrogen tanks will be in use,” a NASA spokesperson confirmed to Gizmodo today.

The new liquid hydrogen tank will have a capacity of 1.4 million gallons, but with a usable space closer to 1.25 million gallons, the spokesperson clarified. The SLS core stage and ICPS require more than 537,000 gallons of liquid hydrogen. Filled with 1.25 million gallons of the super-chilled stuff, the new tank will store more than twice the amount of liquid hydrogen required for a single launch, and with some important room to spare, given that a portion boils off on the launch pad. Combined, the two hydrogen tanks will provide a liquid hydrogen storage capacity of 2.1 million gallons. Construction of the new tank began in 2018.

When preparing for an SLS launch, ground teams flow liquid hydrogen from a storage tank to the base of the Mobile Launcher using transfer lines. From there, the service mast umbilical transfers the propellant into the core stage and ICPS tanks. Once the new tank is complete, ground teams will conduct validations tests to “make sure we’re getting the right pressures, flow rates, no issues with manifolding, and things along those lines,” Parsons said.

An emergency egress system terminus area is also under construction at Launch Complex 39B. In the event of an emergency during launch countdown, astronauts can use this system to safely exit the launch pad area. The system, which wasn’t needed for Artemis 1, will be similar to the one used during the Shuttle program, in which astronauts sat in baskets held by cables. It’s kinda like zip lining, but without the fun.

The upgraded system “will enable astronauts to exit Orion at the Crew Access Arm white room through the mobile launcher tower down to the emergency transportation vehicles on the ground and onward to a safe haven,” according to NASA. The new emergency egress system will feature a larger capacity and various upgrades to meet the demands of Artemis 2 and the upcoming Block 1B SLS rocket required for Artemis 4 and future Moon missions.

For Crawler Transporter 2, teams plan to replace the individual shoes, or tread plates, on its two large tracks, in addition to adding new steering cylinders and doing corrosion control work. Ground teams are also in the midst of repairing damage incurred by the Mobile Launcher during the inaugural launch of SLS. This includes busted pipes, fried cameras, and blast doors on the tower’s elevator that got, uh, blasted.

More on this story: NASA Downplays Launch Pad Damage Caused by SLS Rocket 

Preparations are also underway for the Artemis 2 Orion crew module, which will actually hold a crew during Artemis 2. Similar to Artemis 1, Orion will venture past the Moon and return home to Earth without any activities planned on the lunar surface. That feat—the first Moonwalk since the Apollo 17 mission of 1972—won’t happen until Artemis 3, currently slated for launch in either 2025 or 2026.

The Artemis 2 Orion capsule will feature hardware not included in Artemis 1, “including normal and emergency communication components, display units, hand controllers, full fidelity side and docking hatches, environmental control and life support subsystems for nitrogen, oxygen, water, and air, as well as waste management, and fire detection and suppression,” according to the space agency. Orion’s heat shield will be added before summertime. As for the rocket’s critically important launch abort system, it’s 90% complete in terms of assembly, integration, and testing.

It seems a bit early to be talking about Artemis 2, but late 2024 isn’t that far off, especially as far as NASA timelines are concerned. The space agency isn’t known for hitting deadlines, so this is all very necessary stuff. NASA also benefited from the tremendous success of Artemis 1, allowing it to set its sights firmly on the next mission.

More: 7 Things We Learned From NASA’s Wildly Successful Artemis 1 Mission