A lightweight passive attenuator (1) for spacecraft includes two omega cross-section rings (2), placed symmetrically and defining a gap therebetween, and being the main load path of the light passive attenuator (1). A plurality of damper elements (3) are placed in the gap defined between the two omega cross-section rings (2), and not in the main load path of the light passive attenuator (1), such that the omega cross-section rings (2) and the damper elements (3) are assembled at their ends by attachment elements. The omega cross-section rings (2) have a protruding central part (5) with a plurality of holes (6) for connection with adjacent structures (7, 8) of the spacecraft.