Vehicle external cargo stowage and retrieval apparatus and related control system

Apparatus and method to access external vehicle cargo carriers and cargo are disclosed for moving cargo from a vehicle's roof to the vehicle's hood and returning the cargo to the roof for storage. A particular embodiment consists of using existing vehicle external roof-rack mounts and cargo carriers to allow mobile crossbars to deliver the cargo carrier and the cargo to a position at the front of the vehicle. A self-contained control system provides locomotive force to deploy and retrieve the cargo carrier and cargo. A human interface is used to control the apparatus and includes manual checks to ensure safe use. The apparatus can be used without a control system and operated manually.