Secondary Payload Avionics Units (AUs) and engineering support for Artemis missions including a spare unit, as part of the SLS Secondary Payload Deployment System to control the deployment of secondar... Secondary Payload Avionics Units (AUs) and engineering support for Artemis missions including a spare unit, as part of the SLS Secondary Payload Deployment System to control the deployment of secondary payloads from the Orion Stage Adaptor during these missions. Each AU is comprised of a sequencer, capable of storing and executing multiple deployment scenarios, and a battery to supply power to the deployment system for the duration of the mission objectives.