Educational purposes have been the trigger for CubeSat development. Most of this class of nano-satellites where initially developed as hands-on projects at universities and institutes, mostly being of very simple construction and complexity. However, in the most recent years low cost sensors and mobile technology started to be translated into nano-satellites, and this expanded their possible mission profiles, prompting the attention of companies and government agencies. Today, many tasks that previously where only possible to be developed within a multi-million dollar/euro framework can be accomplished by nano-satellites, at a tiny fraction of their cost. One of the major weaknesses of these devices is the low level of available power onboard, and the lack of efficient state-of-the-art propulsion systems. The present paper provides a throughout discussion on the diverse propulsion technologies used for CubeSat and other micro-satellite systems. If only attitude correction is requested then, present day technologies can be readily used. However, for orbit change or interplanetary nano-spacecraft propulsion, present day technologies are not able to provide the necessary performance under the restricted power budget on-board. New routes are herein proposed for the development of thrusters for nano-satellites and other comparable size spacecrafts.

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<div class="section abstract"><div class="htmlview paragraph">This work aims to expand the applicability of an open-source numerical tool to solve hypersonic gas dynamic flows for space propulsion geometries. This is done by validating the code using two well-known hypersonic test cases, the double cone and the hollow cylinder flare, used by the NATO Research and Technology Organization for the validation of hypersonic flight for laminar viscous-inviscid interactions (D. Knight, “RTO WG 10 - Test cases for CFD validation of hypersonic flight,” in 40th AIAA Aerospace Sciences Meeting &amp; Exhibit, 2002). The Computational Fluid Dynamic (CFD) simulation is conducted using the two-temperature solver hy2Foam that is capable to study external aerodynamics in re-entry flows. In the present work the assessment of hy2Foam to solve hypersonic complex flow features with strong interactions including non-equilibrium effects was demonstrated. Freestream conditions with stagnation enthalpy of 5.44 MJ/kg and Mach number of 12.2, for the double cone case, and stagnation enthalpy of 5.07 MJ/kg and Mach number of 11.3 for the hollow cylinder case were considered. Comparison with newer existing numerical data and experimental data from LENS XX (Large Energy National Shock Expansion Tunnel Version 2) was also performed. Special attention was taken to the phenomenon of vibrational excitation of the molecules. Different vibrational non-equilibrium models were used and compared with the available data. Hy2Foam showed consistent results, with the vibrational non-equilibrium models reducing the discrepancies between numerical and experimental results.</div></div>