After the successful experiences of the two first earth observation satellites ALSAT-1 and ALSAT-2A, launched respectively, in November 2002 and July 2010, the Satellites Development Centre started developing mission analysis tools to be used for the future mission planed by the Algerian Space Agency. In this paper, we focus on the preliminary orbit analysis which represents a critical parameter for the feasibility and the definition of a space mission. The results of orbit analysis are used in the design of the payload, the propulsion and the communication subsystems and to guarantee that the defined ground track and local solar time control windows allow in addition to the quality of the mission data, the station keeping of the satellite in its reference orbit over the lifetime period and the required fuel for de-orbiting the satellite at the end of life.