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• FORESAIL-1 mission measures energetic electron precipitation and solar energetic neutral atom flux • We will demonstrate a cost-efficient de-orbiting and orbit manoeuvring technology without propellants • The goal of the mission is to contribute significantly to the sustainable utilisation of space

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The Electric Power System (EPS) and attitude control system (ACS) are the essential components of any satellite. EPS and ACS efficiency and compactness are substantial for the proper operation and performance of the satellite’s entire mission life. So, realizing the significance of EPS and ACS subsystems for any satellite, they have been assimilated and developed in modular forms focusing on efficiency and compactness. The EPS is comprised of three modules called the solar panel module (SPM), power conditioning module (PCM), and power distribution module (PDM) while the ACS has an embedded magnetorquer coil. For compactness and miniaturization purposes, the magnetorquer coil is embedded inside the SPM. The components used are commercial off-the-shelf (COTS) components emphasizing on their power efficiency, small dimensions, and weight. Latch-up protection systems have been designed and analyzed for CMOS-based COTS components, in order to make them suitable for space radioactive environment. The main design features are modularity, redundancy, power efficiency, and to avoid single component failure. The modular development of the EPS and ACS helps to reuse them for future missions, and as a result, the overall budget, development, and testing time and cost are reduced. A specific satellite mission can be achieved by reassembling the required subsystems.

In modern electrical systems, solar energy extracted is integrated into electrical grid using power converters. In most cases, several inverters are connected across the same dc link so that the circulating currents between the inverter are made zero and the input power is shared among the available inverters. Because of the nonlinear nature of grid-tied photovoltaic (PV) system and the inherent modeling uncertainties, conventional control schemes cannot provide satisfactory performances under all operating conditions. Nonlinear control techniques for grid-tied inverter have been explored in this paper. However, the design of nonlinear controllers for the control of grid-tied parallel inverters has been rarely reported. Therefore, the purpose of this paper is to design a nonlinear controller for the control of grid-tied parallel inverter system. A novel control strategy is devised that utilizes backstepping inspired integral sliding mode control to maintain a constant dc link voltage and control power flow to the grid. An algorithm is developed, which determines the number of inverters connected across the dc link. The control strategy employs Lyapunov approach to ensure stability in an event of disturbance and guarantees robustness. With the proposed control scheme, better and superior performance is observed in transient response, total harmonic distortion minimization and integrating power into the grid at unity power factor. Furthermore, with the control strategy, the available power from the PV array is successfully distributed among multiple inverters operating in parallel.INDEX TERMS Backstepping, dc link, ISMC, parallel inverters.

In space thermal environment, satellites are exposed to multiple heat sources which can deteriorate structural and equipment integrity over long periods of time. Normally radiators are used to release heat, but due to space and weight constraints, it is impossible to mount radiators on small satellites. This problem signifies the importance of thermal analysis of a satellite in every development stage, such as design, manufacturing and testing. The ultimate goal of this work is to analyze a small spacecraft in space thermal environment by considering the effect of various heat sources. Thermal equilibrium equation is achieved which is applied to spacecraft with different shapes and dimensions and temperature is measured for a range of absorption coefficient values (i.e. 0.5 ~ 0.9). Through an experimental setup a method is devised to measure the absorption coefficient of small satellites that can be used for exact temperature measurement. Secondly, the paper presents a preliminary analysis of induced spin produced by small satellites due to asymmetrical colors (different absorptance) of satellite outer surface. The substantial contributors for induced spin are considered and the estimated spin is measured. INDEX TERMS Satellites, Thermal analysis, Temperature, Absorption. I. INTRODUCTION Recently, there is a great emphasis on the development of small satellites by universities and SMEs (small and medium enterprisers) because they are simple, cheaper and easy to launch [1, 2]. In this regard, the first NanoSatellite was developed in 1999 by California Polytechnic State University (Cal Poly) in collaboration with Stanford University, called CubeSat with dimensions 10 × 10 × 10 cm 3 [3, 4]. This provided a new research area to universities and SMEs worldwide in the field of small satellites. Department of Electronics and Telecommunication (DET) at Politecnico di Torino is also working on a comprehensive NanoSatellite project called AraMiS [5], designing small satellites for Low Earth Orbit (LEO). The design process of AraMiS is based on the concept of tiles [6] and modules. The tiles and modules have different dimensions and technology to achieve any desired satellite structure. These modules can be reused for multiple missions that help in significant reduction of the overall budget, design,

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