has part has part has_part participates in participates in experiment payload Payloads are self-contained, and removable, and their presences is independent of vehicle operation. The definition of payload is entwined with definition of vehicle, as vehicle is the transporting method/artifact associated with one or more payloads. A package of elements carried onboard a spacecraft over and above what is necessary for the operation of the vehicle. May refer to the complete set of such elements transported during a mission, or to individual packages transported to support specific mission objectives. A research payload refers to a package of elements specifically dedicated to producing research data and relaying that data to earth. hardware research mission Payload