Thermal and mechanical design and test campaign results of a single-piece structure for the URSA MAIOR nanosatellite

The Sapienza Space Systems and Space Surveillance Laboratory (S5Lab) of La Sapienza University of Rome is involved in the development and manufacturing of the nano-satellite URSA MAIOR (University of Rome la SApienza Micro Attitude In ORbit testing), a 3U CubeSat selected in the framework of QB50 mission, an FP7 project led by the Von Karman Institute of Fluid Dynamics with the aim to demonstrate the possibility of launching a network of 50 CubeSats intended for measuring and analyzing the lower thermosphere. The nano-satellite, scheduled for launch from July 2016 on, carries a multi Needle Langmuir Probe (mNLP) science unit, used to determine the electron temperature and density and the electric potential of plasma, an Attitude Determination and Control System (ADCS) realized by Surrey Space Centre and two experiments: a polymeric drag sail for nano-satellites deorbiting and an innovative cold-gas MEMS (Micro Electro Mechanical System) micro-thruster for attitude control of nano-satellites, developed at the Sapienza Aerospace Research Centre (CRAS). Both the on-board computers and the structure have been designed, manufactured and tested at the local facilities. The structure subsystem is realized from a 100mm × 100mm square aluminium profile to enhance the thermal conductivity and the mechanical properties. The profile le is properly machined to reduce the overall weight while preserving the thermal conductivity features and the structural stiffness. This paper outlines and compares the results from thermal and mechanical analysis and test campaigns. In particular, a PSD (Power Spectral Density) frequency analysis, used to evaluate the stress suffered by the satellite during the launch, is performed. Furthermore, a (1g) sine sweep 5-400Hz test allows evaluating the natural frequency of the structure and a random vibration test allows comparing real results to FEM analysis.