• ottimizzazione
• solari
• traiettorie
• vele

Solar sails have long been seen as an attractive concept for low-thrust propulsion. Due to their no-need of fuel, solar sailing is becoming, with growing interest, object of further research for high-energy missions. One of the most important tasks, during the feasibility analysis and preliminary design of a deep space mission, is the design and optimization of the interplanetary transfer trajectory. The search of minimum time escape trajectories from Earth gravitational field appears to be the first step in such a study. In this thesis work, the continuous time, space and control optimization problem of finding near-minimum time Earth escape trajectories for a solar sail, has been discretized in order to exe- cute the Dynamic Programming algorithm. A performance index that permits to achieve escape, from the analyzed starting orbits, is set up; afterwards an optimization using the DP algorithm is carried out, producing an improvement in terms of time to escape, even if small, with respect to the performance index initial guess solution. Two dimensional trajectories lying onto the ecliptic plane are investigated, using the ideal solar sail model. A characteristic sail accelera- tion of 1 mm/sec2 is considered, neglecting all secondary perturbation effects on the sail. Trajectories are generated starting from two initial orbits of practical interest: a Geosynchronous orbit and a GTO. Trajectories and times to escape are compared with results obtained through another near-optimal method, such as the one that maximizes the instantaneous rate of increase of total orbital energy, largely used nowadays.