The dress rehearsal will demonstrate the team's ability to load more than 700,000 gallons of cryogenic, or super-cold, propellants into the rocket at the launch pad, practice every phase of the launch countdown, and drain propellants to demonstrate safely standing down on a launch attempt. The test will be the culmination of months of assembly and testing for SLS and Orion, as well as preparations by launch control and engineering teams, and set the stage for the first Artemis launch.