Proceedings PaperSmear Velocity In Elliptic Orbits
|Format||Member Price||Non-Member Price|
The effect of elliptic orbit motion on the blurring in an optical sensor was evaluated. The magnitude of the uncompensated relative velocity, the smear velocity, can influence the selection of an orbit for the mission as well as the signal processing requirements. A model of the orbital kinematics and the optical projection effects for a surveillance spacecraft was developed in order to determine the smear velocity. The center of the sensor's field of view (CFOV) is assumed to be directed to track a point of interest on the earth's surface in order to reduce the relative motion. Two different modes of tracking the point are considered: two-axis tracking and three-axis tracking. The lateral variation of the smear velocity across the field of view (FOV) was analyzed. This effect, in conjunction with the frame time, contributes to the smearing or blurring of the image. It must be assessed along with the clutter effects in an evaluation of the image degradation. The smear velocity may range from zero to over 300 meter/second in a typical orbit. The effect would be greater than the effect of drifting clouds in the background. The effect generally increases with increased displacement from the CFOV, and it changes significantly with the observation position along the elliptic orbit.