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  • A Mission Management Unit for Satellite Recovery Experiment

    Paper ID



    • Kishore Jandhyala


    Indian Space Research Organisation (ISRO)






    A Mission Management Unit for Satellite Recovery Experiment By Dr. J.K. Kishore, Mr. Partha B, Ms. S.Selvi, Mr. Parameswaran and Dr. V.K. Agrawal The Satellite Recovery Experiment had an objective to develop a recoverable capsule around 600Kg, launch it on board PSLV to a Low Earth Orbit, conduct micro-gravity experiments, deorbit, deboost and recover it in Indian waters. The physical dimensions of SRE (Sphere-Cone-Flare configuration) had a major impact on the realization of spacecraft electronics for the mission. This mechanical / volume / weight constraints due to the shape of SRE required integration of many functions of the mission into a single system instead of stand alone systems for each function. The SRE mission integrates functions of a traditional spacecraft with the logics required for reentry and recovery which is a major design driver for the Mission Management Unit(MMU). This paper discusses the design of MMU. The MMU is a MA31750 processor based system in a motherboard – daughter board configuration. The MMU is an augmented version of Bus Management Unit as apart from integrating the functions of Telecommand (TC) and Telemetry (TM) processing, Data acquisition from attitude and temperature sensors, Attitude and Orbit control, Thermal Management as in BMU of a traditional spacecraft, it further incorporates Guidance and Navigation, On-board storage of multiple TM format data, its playback of and special logics required by Reentry Measurements into a single system. The house-keeping data and reentry data are stored in EEPROMs so that it can be played back during the short visibilities over ground stations and also recovered after splash down at sea. The MMU provides various modes of operation such as launcher phase, deboost phase and reentry phase. The software is modeled using UML and is developed in Ada. An important feature of software is remote programming which gives scope for incorporating late revisions of mission requirements. The MMU performance during the entire mission of SRE has been excellent and it ensured a precise returning point in the ocean. Key words : Recovery, Storage, Reentry, Processor, UML, Software