A module for forming part of an articulated mast which can be retracted to be stowed and elongated to be deployed, the mast when deployed having a central axis of elongation and a plurality of these modules. Each module has at least three rigid non-folding station rods joined to form a rigid station, and an equal number of non-folding longerons, each hingedly connected to a corner of the station. Four diagonal segments are formed as part of two flexible inelastic cables, which are brought together at a control which always holds one of the cables, and passes the other. The control includes a releasable catch to hold the other cable when its segments are at lengths respective to a deployed module.