Figure 13- - uploaded by Giovanni B. Palmerini
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Polarized light beam path across the LC screen
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Passive attitude stabilization techniques, while not sufficient to satisfy all requirements, are worth to be considered in every mission design since, at least, they are able to reduce the amount of active control needed. The paper considers the gravity gradient stabilization and, standing its lack of control about yaw axis, deals with its augmenta...
Context in source publication
Context 1
... a preferred orientation can be changed according to an externally imposed electric field. In a classical LCD this property is exploited to drive ad hoc a polarized light beam: as an example ( figure 13) the beam filtered by the bottom polarizer is rotated across an extremely thin layer of LC in a helicoidal way to match the polarization properties of the filter at the top. When an external electric field is applied, the LC orientation changes, disrupting the helicoidal path, and therefore vanishing the orientation match at the upper polarizer, so that no light beam will cross the device. ...
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Actively controlling the attitude of the solar sail is necessary to adjust the solar radiation pressure force for trajectory transfer and orbit control. The special configuration of the solar sail makes it very important to develop a unique attitude control strategy that differs from traditional methods. An attitude control method, based on shape v...
Citations
... Solar heating of spacecraft causes antennas far from the sun to bend in the direction of satellite rotation, while antennas near the sun bend in the opposite direction of satellite rotation. Palmerini and Sgubini [6] enhanced the stability of the gravity gradient by adjusting the solar reflector and absorption surface. ...
An analytical dynamic model is presented for a spacecraft with multiple large flexible structures. Based on the partial differential equations (PDEs) of the motion of the solar panel and deployable arm, the governing equations of the main-body and deployable antenna and the boundary conditions at each end point are used to obtain the frequency and mode shapes of the system. Then, the ordinary differential equations (ODEs) of the system can be obtained from the orthogonality relations and mode shape. The influence of the deployable antenna on the frequencies and mode shapes of the spacecraft is investigated. The frequency veering and mode interchanged phenomenon are observed with the variation of the diameter of the deployable antenna. Using the ODEs, the dynamic responses of the spacecraft are calculated to study the influence of the control torque on the attitude and position of the antenna in the attitude maneuver.
