Trajectory design is a research area that involves the creation of optimal paths or routes for vehicles, spacecraft, projectiles, or other objects to follow in order to achieve particular objectives. This can include minimizing fuel consumption, maximizing speed, avoiding obstacles, or reaching a specific target. Trajectory design often involves the use of mathematical models, algorithms, and optimization techniques to find the most efficient and effective paths for a given scenario. The field has applications in a wide range of industries, including aerospace, navigation, robotics, and transportation.