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Abstract: In this paper, the control system of the first Algerian microsatellite in orbit Alsat-1 is presented. Alsat-1 is a 3-axis stabilised microsatellite, using a pitch momentum wheel and yaw reaction wheel, with dual redundant 3-axis magnetorquers. A gravity gradient boom is employed to provide a high degree of platform stability. Two vector magnetometers and four dual sun sensors are carried in order to determine the attitude. This paper examines the low Earth orbit (LEO) control system requirements and design in the context of a real system, the Surrey Satellite Technology Limited (SSTL) advanced microsatellite platform and puts forward designs for the control system to match the advanced capability of the enhanced microsatellite platform. Numerical results show the effectiveness of the implementation. Comparison with in orbit results is presented to evaluate the performance of the control system during accurate Nadir pointing control. [Copyright &y& Elsevier]

Highlights: [•] The influence of the orbit eccentricity on the performance of the ADCS pointing is investigated. [•] The satellite attitude dynamics and kinematics was modelled. [•] A Quaternion-based Extended Kalman Filter was analyzed by considering the orbit eccentricity. [•] This work is very helpful in the preliminary design stage of the spacecraft. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents the in-orbit observations of single event upset (SEU) and multiple bit upset (MBU) activity in the commercial random access memories (RAM) onboard the first Algerian microsatellite Alsat-1. The application of the quasi-cyclic codes for double-bit error detection and correction in commercial memories for use onboard Alsat-1 is presented. The performance of the proposed quasi-cyclic codec is measured and compared with two different error detection and correction (EDAC) devices, using the same FPGA technology. It is shown that such a technique is very efficient to detect and correct double bit errors. The results show that a fast and accurate data decoding is achieved and that the algorithm is robust, which makes it applicable in low earth orbits. [Copyright &y& Elsevier]