Concept Study Of Laser Propulsion And Laser Launching Micro-Satellites

Laser propulsion is an advanced technology with widely potential application. Some performances such as high specific impulse, low cost, good safety and reliability can be obtained by laser propulsion system, which might be used in launching micro-satellites with speediness, maneuverability, and batching. The laser propulsion system can also be used in on-orbit satellites propulsion to operate conveniently.In this thesis, firstly, an overview of recent development of laser propulsion was presented. The lightcraft technology was analysed and discussed extensively. Some problems and the road map for lightcraft technology were also given. After different laser propulsion modes were discussed in detail, the advantages, technical obstacles and the application range were indicated for those different modes. It's very useful to choose a proper propulsion mode for some different missions.Then, based on the analysis above, the concept design of ground based laser launching micro-satellites was performed. The system was divided into five sub-systems, and each sub-system's performance parameters or methodology were investigated. The results show that for ground laser launching, the optimum specific impulse range of laser thruster is a range from 500s to 1200s, while the optimum wavelength of laser is around lum according to the investigation. Also, the launch pad, space vehicle design and control methodology were discussed.Lastly, a motion model for space vehicle based on laser propulsion was developed, and trajectory optimization was performed by numerical computation. Some features of the trajectory were obtained. The optimal control problem on the maximum payload for launching space vehicle to LEO is solved by using sequential quadratic programming. The results show that the double modes (air-breathing mode and rocket mode) vehicle can gain the largest payload ratio (up to 35.5%). Unlike traditional trajectory, an unusual backswing trajectory feature is obtained for some optimal trajectories.The study shows that there are not any fundamental difficulties for realizing laser propulsion. The conclusion will give some tutorial advices for laser propulsion design and demonstration, and can be available for reference in the design of ground based laser launch system.