Design and Optimization of Low-Thrust Transfer Trajectory with Aerogravity Assist
- Paper number
IAC-06-A3.P.2.07
- Author
Dr. Haibin Shang, Harbin Institute of Technology, China
- Year
2006
- Abstract
Highly efficient low-thrust engines can provide new opportunities for interplanetary exploration mission. Additionally, applying aerogravity assist technique to low-thrust trajectories can shorten mission durations and reduce propellant costs further, in which method, a lifting body flies through the atmosphere of the planet to turn the in any desired direction. However, the design and optimization of low-thrust trajectory with planetary aerogravity assist is a formidable task. In this paper, we presented the patching condition for AGA trajectory. Then a hybrid method, which combines direct and indirect method, is utilized to optimize the optimal-fuel trajectory to rendezvous with Ceres by Mars aerogravity assist. In order to improve the convergence of optimal problem, and avoid the singularity of classical orbital elements, a modified set of equinoctial orbital elements is utilized in the governing dynamics of a powered spacecraft in an inverse-square gravity field. Then the patching condition for designing aerogravity assist transfer trajectory is presented by analyzing the characteristics of AGA trajectory. This patching condition is the significant principle for AGA trajectory design and optimization. It can be used to find potential trajectories to next target at an encounter. Based on the patching condition, the trajectory profile is designed using a hybrid method through three steps. Firstly, an Earth-Mars flyby problem is solved, the launch date is not specified, and the performance goal is maximize the final mass. Then the optimal-fuel Mars-Ceres rendezvous trajectory is optimized, and the departure hyperbolic velocity at Mars should satisfy the patching condition. Some initial designing parameters of trajectory profile can be obtained from above two problems. Finally, taking the parameters as the initial guesses, the optimal-fuel transfer trajectory to rendezvous with Ceres is found. The calculation demonstrates our method is an efficient approach to design and optimize the low-thrust trajectory with AGA technique. Keywords: low-thrust; aerogravity assist; hybrid method; optimal-fuel;
- Abstract document