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SLS Rocket Pathfinders Prepare Teams for One-of-a-Kind Hardware Prior to Moon Mission

NASA’s Pegasus barge arrived Sept. 27 at the agency’s Kennedy Space Center in Florida with the core stage pathfinder for NASA’s Space Launch System (SLS) rocket. The pathfinder will be used for lift and transport practice techniques inside Kennedy’s Vehicle Assembly Building to prepare for the first lunar mission of SLS and NASA’s Orion spacecraft, Artemis I.

The core stage pathfinder is one of three pathfinder structures used by NASA to train lift crews on best practices for moving and handling the SLS rocket flight hardware. In addition to the core stage pathfinder, there is an RS-25 engine pathfinder and a solid rocket booster pathfinder. Designed as full-scale mockups of the flight hardware, the three SLS pathfinders each reflect the shape and size of the individual components of the rocket.

Space Launch System (SLS) core stage pathfinder is positioned in the B-2 Test Stand at NASA’s Stennis Space Center
NASA’s Space Launch System (SLS) core stage pathfinder is positioned in the B-2 Test Stand at NASA’s Stennis Space Center near Bay St. Louis, Mississippi. The Pathfinder is the same shape, size and weight (without propellants loaded) as the actual SLS core stage flight hardware. Stennis work crews used it in August to train and practice handling and lifting techniques needed for the core stage flight hardware when it arrives at Stennis for testing in 2020.

The number of pathfinders for the rocket allow multiple teams to use the pathfinders for different operations and procedures at several processing locations. After teams at Kennedy practice with the core stage pathfinder in the VAB, NASA’s Exploration Ground Systems will begin stacking operations with the booster pathfinder structures to simulate an aft booster assembly and bottom center segment stacking operation. All this practice prepares teams for the same upcoming tasks with the actual flight hardware.

Engineers previously used the core stage pathfinder in August at NASA’s Stennis Space Center near Bay St. Louis, Mississippi, where crews practiced similar lift and handling procedures into the B-2 Test Stand ahead of the Green Run test series for the core stage.

“After the pathfinder lift operations were complete, the unit was installed into the B-2 Test Stand at Stennis,” said Barry Robinson, B-2 Test Stand core stage test project manager at Stennis. “Among other things, the exercise helped us identify minor facility modifications early enough to provide the time needed to make the corrections prior to the arrival of the core stage flight hardware.”

Equipped with the largest rocket stage NASA has ever produced and the largest twin boosters ever built for flight, the SLS rocket for the Artemis missions will be the most powerful rocket in the world, enabling astronauts in Orion to travel to the Moon’s south pole. The two massive propellant tanks in the rocket’s 212-foot-tall core stage power the four RS-25 engines at the bottom of the rocket. On either side of the core stage are two, five-segment solid rocket boosters. Together, the engines and the boosters will produce a combined thrust of 8.8 million pounds during launch and flight. The rocket for Artemis I will tower at 322 feet.

“Practicing operations with pathfinders offers teams hands-on experience for managing and handling the immense structures before this one-of-a-kind flight hardware arrives,” Robinson said.

Because the pathfinders replicate the flight hardware, the various pathfinders validate ground support equipment, and flight hardware access techniques as well as train handlers to transport the equipment on a variety of terrains with different vehicles, like the Pegasus barge and Kennedy’s mobile launcher, and demonstrate how the equipment can be integrated within facilities.

“Experience is the best teacher,” said Jim Bolton, EGS core stage operations manager. “Pathfinders allow crews to practice lifting, accessing and transporting techniques that we prefer not to do for the first time with the flight hardware. Practicing with a pathfinder reduces risk and builds confidence.”

As crews at Kennedy use the SLS booster and core stage pathfinders for the same processes the actual flight hardware will undergo when processed at Kennedy for Artemis I, completed flight hardware for SLS and Orion will also be delivered.

“NASA’s first Artemis mission flight hardware has progressed into final assembly and integration, moving well beyond the early design and manufacturing stages of development,” said Mark Prill, SLS core stage pathfinder lead. “Flight hardware for both the SLS rocket and the Orion spacecraft will continue to be delivered to Kennedy as NASA prepares for the launch of Artemis I.”

NASA is working to land the first woman and the next man on the Moon by 2024. SLS, along with Orion and the Gateway in orbit around the Moon, are NASA’s backbone for deep space exploration. SLS is the only rocket that can send Orion, astronauts and supplies to the Moon on a single mission.

For more on NASA’s SLS, visit:

Tracy McMahan
Marshall Space Flight Center, Huntsville, Alabama