Hybrid Estimation of Solar Radiation Pressure for a Spinning Solar Sail Spacecraft

A hybrid estimation technique was applied to determine the solar radiation pressure (SRP) force acting on the solar sail spacecraft Interplanetary Kite-craft Accelerated by Radiation of the Sun (IKAROS). To evaluate the SRP force, only tracking data obtained during coast arcs are used. The orbit determination and SRP parameters estimation is implemented using batch weighted least squares. The observables are X/X band two-way Doppler and range measurements. The actually encountered solar radiation pressure acceleration of the IKAROS spacecraft is found to amount to only 88% of the value of the prelaunch simulations. Furthermore, the hybrid technique improves the accuracy of the solar radiation pressure acceleration estimation almost by a factor of five. These results underline the importance of applying a hybrid evaluation of not only the solar radiation pressure force but also the torque for navigation of a solar sail spacecraft.