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 SpaceRobotics Laboratory and V-Lab of the II Faculty of Engineering of Bologna University in collaboration with theSpace 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 redundanttelecommunication 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 or3U Cubesats. The additional volume can be used for more complex payloads. Thus the satellite can be used as lowcost 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 andmomentum dumping and three reaction wheels for fine control. It has a total dimension of about 50x50x50 mm andcompletely realized by the Space Robotics Laboratory during the PhD activities of one of the authors. Amicrocontroller implements the control law autonomously or by commands from ground, . taking data frommagnetometers integrated in the control system, by solar arrays; reaction wheels and magnetic coilsThe Cubesat structure has been realized in plastic material (ABS) through "rapid prototyping" technique, thanksto the facilities provided by the V-Lab. The "rapid prototyping" technique has several advantages including fastimplementation and low cost. Moreover, concerning the construction of a small satellite, this technique is very usefulthanks to the accuracy achievable in details, which sometimes are difficult and expensive to realize with the use oftools machine. The structure must be able to withstand with the launch loads. For this reason, several simulationsusing 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 maincomponents of the system are the radios, the antennas (one of them is manufactured inside the ABS structure), theamplifiers and the microcontroller. It has been implemented a communication protocol used mainly by radioamateurs, the AX.25 protocol. The communication system has the capability to transmit both telemetry and datafrom the payload, in this case a microcamera.