Satellite-borne computer system

The invention provides a satellite-borne computer system which comprises a processing system, an arbitration system and a bus system, the processing system comprises a first processor and a second processor, the bus system comprises a first bus, a second bus and a third bus, and the first processor and the second processor are connected with the arbitration system, the first bus and the second bus respectively. The arbitration system is connected with the third bus; in an initial state, the first processor is in a working state and is used for receiving an instruction from a ground control device through the first bus, collecting satellite service data of a satellite through the second bus, outputting an attitude control instruction to the satellite and monitoring power consumption of each system of the satellite through the third bus; and when the first processor is abnormal or receives a switching instruction from the ground control device, the arbitration system controls the processing system to be switche