This paper focuses on the issues regarding the software based testing approach which mainly utilizes the software models for the satellite environment and the satellite itself. This approach facilitates the use of real on-board software in a virtual satellite environment and hence gives an excellent means of system design qualification and performance verification. Use of FPGA as an on-board computer leads to the requirement of implementing the attitude control algorithms in the hardware which emphasizes the need of its testing in the loop with the simulator. Two different type of simulation environments are used to increase the credibility of the results
