Technicians with NASAs Exploration Ground Systems rehearse lifting operations using a mock-up of the Space Launch System (SLS) aft booster segment, referred to as a pathfinder, inside the Vehicle Assembly Building (VAB) at the agencys Kennedy Space Center in Florida on Sept. 11, 2020, in preparation for Artemis I. The exercise involved preparing the aft pathfinder segment in High Bay 4 of the VAB and moving it over to High Bay 3, where it was placed on the mobile launcher. Stacking of the actual booster segments will occur later this year, before the SLS core stage arrives at Kennedy. Artemis I is the first in a series of increasingly complex missions that will test SLS and the Orion spacecraft as an integrated system prior to crewed flights to the Moon.