The upper stage for NASA’s Artemis II SLS (Space Launch System) rocket sits in the transfer aisle of the Vehicle Assembly Building at NASA’s Kennedy Space Center in Florida on Wednesday, April 16, 2025, after teams with the agency’s Exploration Ground Systems Program transported the four-story propulsion system from the spaceport’s Multi-Payload Processing Facility (MPPF). Technicians fueled the SLS upper stage, known as the interim cryogenic propulsion stage, with hydrazine for its reaction control system at the MPPF and will now integrate the four-story propulsion system with SLS rocket elements atop mobile launcher 1.