PLASTIC CUBESAT: AN INNOVATIVE AND LOW-COST WAY TO PERFORM APPLIED SPACE RESEARCH AND HANDS-ON EDUCATION

摘要

This paper describes the design and the manufacturing of a Cubesat realized within the activities of Space Robotics Laboratory and V-Lab of the II Faculty of Engineering of Bologna University in collaboration with the Space System Laboratory of the University of Rome "La Sapienza". Despite its small size, this single unit (1U) Cubesat has a system for active attitude control, a redundant telecommunication system, a payload camera and an high efficiency power control system. The subsystems developed for this Cubesat have been also designed to be scaled up for larger satellites as 2U or 3U Cubesats. The additional volume can be used for more complex payloads. Thus the satellite can be used as low cost platform for companies, institutions or universities to test components in space. The attitude control subsystem is based on active magnetic system with magnetorquers for detumbling and momentum dumping and three reaction wheels for fine control. It has a total dimension of about 50x50x50 mm and completely realized by the Space Robotics Laboratory during the PhD activities of one of the authors. A microcontroller implements the control law autonomously or by commands from ground, taking data from magnetometers integrated in the control system, by solar arrays; reaction wheels and magnetic coils. The Cubesat structure has been realized in plastic material (ABS) through "rapid prototyping" technique, thanks to the facilities provided by the V-Lab, The "rapid prototyping" technique has several advantages including fast implementation and low cost. Moreover, concerning the construction of a small satellite, this technique is very useful thanks to the accuracy achievable in details, which sometimes are difficult and expensive to realize with the use of tools machine. The structure must be able to withstand with the launch loads. For this reason, several simulations using a FEM code and intensive vibration test campaign have been performed in the system development phase. The developed communication subsystem has small dimensions, low power consumption and low cost. The main components of the system are the radios, the antennas (one of them is manufactured inside the ABS structure), the amplifiers and the microcontroller. It has been implemented a communication protocol used mainly by radio amateurs, the AX.25 protocol. The communication system has the capability to transmit both telemetry and data from the payload, in this case a microcamera.