Structural and Orbital Conditions on Response of Large Space Structures

Effects of orbital and structural initial conditions, such as initial structural axial deformation, pitch (attitude) angle, and orbit altitude have been investigated on the subsequent orbital motion (time variation of orbit radius), attitude or pitch motion (time variation of pitch angle), and axial motion (time variation of axial length) of a large space structure in low earth orbit (LEO) and geosynchronous earth orbit (GEO). The space structure is assumed to be only axially flexible and executing a planar motion under the action of the earth's gravitational force. In LEO it is observed that the initial values of the axial deformation and pitch angle have appreciable effects on the structure's subsequent axial and attitude motions, whereas they have negligible effects on the structure's orbital motion. In GEO, the effects are found similar to those in LEO, except that the initial values of pitch angle have no effect on axial deformation. Furthermore, the investigation shows that the response of the space structure is greatly affected by the change in the orbit altitude. The study also indicates that flexibility of the structure has significant influence on its pitch librational motion.