Abstract: A long, elastically deployable tubular boom structure consisting of two or more thin-walled booms with a continuous longitudinal slit-opening along its entire length on the backside and a composite reinforced or metallic construction. The slit-opening, thin-walled tubular section accompanied by the boom elastic properties and unique fastening method between the boom segments allows the segmented boom to be flattened and then rolled up into an extremely compact cylindrical stowage volume. The boom elastically and immediately deploys from a rolled stowed configuration under its own strain energy without use of a motor or other complicated actuators/mechanisms. The segmented construction of multiple tube elements allows for unlimited boom lengths and enables unlimited structure scaling.