A spacecraft (20) is adapted for orbital flight in two alternative modes, referred to as the earth-oriented and quasi sun-oriented modes. The spacecraft comprises a spacecraft body (21), at least one solar array (44, 46) extendible outwardly from the spacecraft body, passive attitude control means (58) utilizing gravity gradient stabilization means which is extendible and retractable relative to the spacecraft body (21), and active attitude control means (69, 71). The gravity gradient stabilization means (58) is effective when extended to stabilize the spacecraft in the earth-oriented mode, and the active attitude (69, 71) control means is effective to stabilize the spacecraft in the quasi sun-oriented mode.