考虑天基照相机观测中小尺寸空间目标时具有能耗低、精度高以及易于小型化实现等优势，研究了利用天基照相机监测空间目标的轨道确定和可观测性计算方法。分析了太阳同步轨道作为天基监视轨道的优点，结合目前国外的几种天基卫星轨道类型，设计了天基卫星轨道，在此基础上仿真分析了对不同轨道类型空间目标的可见观测弧段。根据目前地基光学观测设备的测轨精度和轨道动力学模型误差，添加了不同的测轨系统误差、随机误差及一定的动力学模型误差，仿真分析了对不同轨道高度空间目标的定轨精度。分析结果表明，采用6天7分钟/两天的天基光学测轨数据对近地轨道的空间目标定轨时，若测轨精度优于30″，动力学模型误差小于50%，则定轨精度与美国编目轨道(TLE)精度相当。采用10分钟/天的天基光学测轨数据对地球同步轨道上的空间目标定轨时，若测轨精度优于10″，动力学模型误差小于50%，则定轨精度在美国编目轨道精度范围内。

As space-based cameras have advantages of lower energy consumption, higher accuracy, and easy to be miniaturized when they are used to observe space objects with middle or smaller sizes, this paper explores the orbit determination method and observability calculation method of space objects by space-based cameras. The advantages that the sun synchronous orbit is set as a space-based satellite orbit are analyzed and a space-based satellite orbit is designed by referencing several foreign space-based satellite orbits. Then the visible arc sections of space objects for different orbit types are simulated based on the space-based satellite orbit. According to the orbit measurement accuracy of existing space based optical observation equipment and errors of orbit dynamic model, the different system errors ,random errors and dynamic model errors for the orbit measurements are added. Finally, the orbit determination precisions for space objects in different orbital altitudes are analyzed. Analysis results show that, for determining space target in low earth orbit with 6 of 7 minutes a day / two days of space-based optical measurement orbit data, the orbit determination precision is coincident with that of the United States of America cataloging (Two-line Elements,TLE) when the orbit measurement accuracy is better than 30″ and the dynamic model error is less than 50%. Moreover, for determining space target in earth synchronous orbit with 10 min / day of space-based optical measurement orbit data, the orbit determination precision is in the orbit accuracy range of the United States of America cataloging when the orbit measurement accuracy is better than 10 " and the dynamic model error is less than 50%.