This paper presents a preliminary design of a smart composite telescope for space laser communication.
The smart composite telescope will be mounted on a smart composite platform with Simultaneous
Precision Positioning and Vibration Suppression (SPPVS), and then mounted on a satellite. The laser
communication is intended for the Geosynchronous orbit. The high degree of directionality increases the
security of the laser communication signal (as opposed to a diffused RF signal), but also requires
sophisticated subsystems for transmission and acquisition. The shorter wavelength of the optical spectrum
increases the data transmission rates, but laser systems require large amounts of power, which increases the
mass and complexity of the supporting systems. In addition, the laser communication on the
Geosynchronous orbit requires an accurate platform with SPPVS capabilities. Therefore, this work also
addresses the design of an active composite platform to be used to simultaneously point and stabilize an
inter-satellite laser communication telescope with micro-radian pointing resolution. The telescope is a
Cassegrain receiver that employs two mirrors, one convex (primary) and the other concave (secondary).
The distance, as well as the horizontal and axial alignment of the mirrors, must be precisely maintained or
else the optical properties of the system will be severely degraded. The alignment will also have to be
maintained during thruster firings, which will require vibration suppression capabilities of the system as
well. The innovative platform has been designed to have tip-tilt pointing and simultaneous multi-degree-of-
freedom vibration isolation capability for pointing stabilization.
This research focuses on a finite element analysis of active vibration suppression capabilities of a smart
composite platform, which is a structural interface between a satellite main thruster and its structure and
possesses simultaneous precision positioning and vibration suppression capabilities for thrust vector control
of a satellite. First, the combined system of the smart composite platform and the satellite structure are
briefly described followed by the finite element modeling and simulations. The smart platform
piezoelectric patches and stacks material properties modeling, for the finite element analysis, are developed
consistent with the manufacturer data. Next, a vibration suppression scheme, based on the modal analysis,
is presented and used in vibration suppression analysis of satellite structures of the thrust vector under the
thruster-firing excitation. The approach introduced here is an effective technique for the design of smart
structures with complex geometry to study their MIMO active vibration suppression capabilities.
Adaptive or intelligent structures which have the capability for sensing and responding to their environment promise a novel approach to satisfying the stringent performance requirements of future space missions. This research focuses on a finite element analysis active vibration suppression of an intelligent composite platform that is designed for thrust vector control of a satellite thruster and has simultaneous precision positioning and vibration suppression capabilities. This smart platform connects the thruster to the structure of the satellite and has three active struts and one active central support with one piezoelectric stack in each. A finite element harmonic analysis was employed to develop a vibration suppression scheme, which was then used to study the vibration control of the satellite structure using the vibration suppression capabilities of the intelligent platform mounted on the satellite. The applicability of the model is first demonstrated on a single strut using a one-dimensional approach. This approach is then extended to the full intelligent composite platform employing a three-dimensional approach. In this approach, the responses of the structure to a unit external force as well as unit internal piezoelectric control voltages are first determined, individually. The responses are then assembled in a system of equation as a coupled system and then solved simultaneously to determine the control voltages and their respective phases for the system actuators for a given external disturbance. This approach is an effective technique for the design of smart structures with complex geometry to study their active vibration suppression capabilities and effectiveness.