A HELIOGYRO SPACECRAFT IS A SPECIFIC TYPE OF SOLAR SAIL THAT GENERATES THRUST FROM THE REFLECTION OF SOLAR PHOTONS. THE PROPOSED RESEARCH FOR THIS FELLOWSHIP WILL ADDRESS THE LIMITATIONS OF CURRENT ANALYTIC MODELS AND CONTROL DESIGNS FOR A HELIOGYRO SPACECRAFT TO DEVELOP PRACTICAL SOLUTIONS. THE FIRST OBJECTIVE IS TO DERIVE NEW EQUATIONS OF MOTION FOR THE ESSENTIAL BLADE DYNAMICS. THE REDUCED ORDER MODEL FOR A HELIOGYRO SPACECRAFT WILL INCLUDE MULTIPLE DEGREES OF FREEDOM COUPLED DYNAMICS SOLAR RADIATION PRESSURE LOADING AND TORQUE SOURCE BOUNDARY CONDITIONS ALL OF WHICH ARE LACKING FROM THE CURRENT ANALYTIC MODELS. THE SECOND OBJECTIVE IS TO DEVELOP A ROOT CONTROL SYSTEM THAT EFFECTIVELY DAMPS THE STRUCTURAL MODES OF A HELIOGYRO SPACECRAFT. THE FINAL OBJECTIVE IS TO DETERMINE THE BLADE BEHAVIOR DURING INITIAL SPIN UP OF THE SPACECRAFT AND BLADE DEPLOYMENT. THE MAIN METHODS USED TO ACCOMPLISH THESE RESEARCH OBJECTIVES WILL INCLUDE CLASSICAL CONTROL THEORY IN CONJUNCTION WITH IMPEDANCE CONTROL AND A THOROUGH UNDERSTANDING OF THE BLADE DYNAMICS. THE HELIOGYRO SPACECRAFT MODELING WILL BEGIN WITH SIMPLIFIED LINEAR ASSUMPTIONS. THE COUPLING AND NONLINEARITIES WILL BE ADDED INCREMENTALLY TO THE MODEL. THE PROPELLANT FREE HELIOGYRO IS A LONG DURATION SUSTAINABLE SPACECRAFT WHOSE MANEUVERABILITY ALLOWS IT TO ATTAIN PREVIOUSLY INACCESSIBLE ORBITS FOR TRADITIONAL SPACECRAFT. CONTINUING RESEARCH IN PRACTICAL HELIOGYRO CONTROL WILL SIGNIFICANTLY ADVANCE THE TRL OF THIS INNOVATIVE DESIGN IN TURN LOWERING THE COST OF EXISTING MISSIONS AND OPENING UP EXCITING NEW MISSION POSSIBILITIES.