Fuel-Time Optimal Study Of Useless Reentry Spacesraft

The potential safety hazard of space debris and useless satellites to the normal operating satellites could not be overlooked. It is necessary to take practical measures to make space debris and useless satellites reentry into the Earth's atmosphere, it is satellite's reentry. Satellite's reentry has many ways, but at the present the most maturational way is jet de-orbit. This study is not more in our country, so as the development of space industry, developing this study is most necessary. This paper adopt jet engine to de-orbit. What we care is that the time and fuel are all economical, so optimal theory is used to analyze it. The concrete work includes:Firstly, the mathematics model for reentry has been founded. With the problem of optimal continuous thrust coplanar orbit transfers is studied in this paper, and a simplification in the foundation of actual dynamics model and the differential equation of aircraft movement are put forward, non-dimensioned the equations has been set. An optimal mathematics guidance model for orbit transfers is accomplished by the optimal control theory. Every kind of terms of extremum is analyzed.Secondly two targets of fuel-time are optimized with optimal control and TPBVP. Every kind of terms of boundary to this request of reentry is analyzed, the simulation result for time-changing problem and time-fixed is given, and gained most optimal control curve of attack angle, most switch function of engine and most optimal track of fight. Then the connection of fuel and time with different engine thrust is studied.Finally the fuel problem of satellites reentry from another point of view is analyzed, namely compute the value of the perigee decrease for fixed fuel. Use the first-order gradient algorithms to simulate rudely, at this study direct shooting method to do precision simulation is used, and the feasibility of time-cost method is validated with this methods.