Abstract: A structural array and electrical rotary joint for transmitting an electrical power between large space structures having relative rotational movement therebetween is disclosed as including large support framework structures A and B which rotate relative to one another about a common axis of rotation X. A rotary interface joint 14 is defined between the structures A and B. A cylindrical hub member C is carried by the structure A and a cylindrical hub member is carried by support structure B with hub member C being received concentrically within hub member D for relative rotation. Tension connecting cables connect hub member C and hub member D with their associated outer structures A and B whereby relative rotational movement between structures A and B is transmitted to the cylindrical hub members for unitary motion therewith.