The Diffuse X-ray Spectrometer (DXS) was a single experiment shuttle payload designed to fly on multiple missions. The primary objective of the DXS payload was to obtain measurements on the diffuse soft X-ray background radiation in the Milky Way Galaxy. DXS flew as a shuttle cargo bay attached payload using the Hitchhiker avionics and Shuttle Payload of Opportunity Carrier (SPOC) hardware, which provided support systems for power, command, and telemetry to the DXS instruments. DXS was first flown on the STS 54 mission.