Abstract:The concept of a rotor-equipped spacecraft for atmospheric entry can be traced back to the early years of the Space Race, in which it was proposed for an Earth-entry manned capsule. Employing an unpowered rotor in autorotation can produce lift offering increased cross-range potential, enhanced maneuverability, and “soft” landing capability. It is estimated that a rotor recovery system would account for less than 15% of the vehicle’s landing weight. A literature review addressing the advantages of rotary-type decelerators for spacecraft is compiled in this paper. First, we cover industry development of rotors for decelerating dropped cargo and feasibility studies of operation in supersonic conditions. Then, the efforts at NASA and other research partners during the 1960’s are reviewed with an emphasis on results from analytical studies and wind tunnel testing. Next, we study solutions of previously derived equations of motion for the dynamic behavior of rotor entry vehicles under variable configurations. Finally, we review more recent rotor entry, descent and landing efforts in particular: the late 1990’s Roton project and rotor systems for atmospheric descent and in-situ exploration of planetary bodies.