Sustainer electric propulsion system application for spacecraft attitude control
- Paper number
IAC-08.C4.4.3
- Author
Dr. Vladimir Obukhov, RIAME MAI, Russia
- Year
2008
- Abstract
Results of the analysis for the possibility to control spacecraft attitude by the hinged sustainer electric propulsions at the insertion stage in accordance with the selected plane configuration for the solar panel (SP) orientation to Sun are presented in the paper. Solar panels are oriented to Sun by rotating spacecraft relative to its longitudinal axis by a roll angle and further solar panel rotation relative to its axis until the normal to the SP surface coincides with the direction to Sun. The spacecraft motion was studied on the basis of the data of ballistic calculation for the insertion trajectory of about 180 days in duration. While analyzing peculiarities of spacecraft control relative to its center of mass, three legs of insertion trajectory, which are the most typical from the point of view of yaw and pitch angles variation, were considered: initial (0-3 days), middle (50-60 days), and final (140-143 days). Initial Sun location relative to the insertion trajectory was varied. It was revealed as a result of study for the orientation of angular motion associated with the SP orientation to Sun that variations of roll angles and solar panel rotation angles are of complicated oscillatory nature with abrupt variations and rather high values of acceleration in the perigee region. For the considered options of Sun location relative to the insertion trajectory the maximum acceleration in the roll angle at the precise SP orientation to Sun was 2.01×10-6 rad/s2, and in the SP rotation angle - 1.02×10-6 rad/s2. It was revealed as a result of the control moment assessment that the gravitational moment influence on the process of angular motion control depends upon the spacecraft axis. Presence of gravitational moments may cause both reduction and increase in control moment requirements. Maximum value of control moment relative to the spacecraft longitudinal axis is 35×10-3 Nm. Analysis for the deflections of cruise propulsions for controlling spacecraft attitude and SP orientation showed that the maximum values of propulsion deflection angles are near the perigee point and are about 5°; at that the duration of legs, at which these deflections are noticeable, is about 0.1 day. Thrust loss will not be more than 0.4deflections of cruise propulsions the operation of spacecraft attitude control system will not influence control for the SC center of mass motion. Studies for the possibility to reduce cruise propulsion rotation angles resulted in the following: it is possible to reduce control moments and deflections of cruise propulsions due to small deviations of SP orientation to Sun. Possibility to change one variant of the SP orientation to Sun by another differing by the sign of the SP rotation angle is important for reducing control moment values. At the accuracy of SP orientation to Sun of at least 10° the cruise propulsion deflection may be about 2-3°. The research was made at the partial support of the RFFI grant 07-08-13548-???_?
- Abstract document
- Manuscript document
IAC-08.C4.4.3.pdf (🔒 authorized access only).
To get the manuscript, please contact IAF Secretariat.