Gravity-assist fuel-optimal low-thrust trajectory design using hybrid optimization techniques

Vishala Arya, Ehsan Taheri, Robyn Woollands, John L. Junkins

Research output: Contribution to journalConference articlepeer-review


Low-thrust propulsion technology and planetary gravity-assist maneuvers make a promising combination for deep space explorations. Hybrid optimal control methods have proven to be an excellent solution framework which exploits the advantages of both direct and indirect optimization methods, while alleviating their drawbacks. We employ a recently introduced hyperbolic tangent smoothing method to design low-thrust interplanetary trajectories with gravity-assist opportunities. Gravity-assist maneuvers lead to multiple-point boundary-value problems, and to solve them, we use a two-level hybrid optimization method. At the first level, a particle swarm optimization algorithm is used to perform a global search over the unknown parameters of an easy-to-solve problem, namely, a problem with smoother control input. The second level improves upon the solution of the first level to obtain the fuel-optimal solution. In order to gain further insights into the thrusting structure, a numerical continuation is performed over the maximum value of the thrust for a problem from the Earth to Mars via a fly-by with Venus, wherein the notion of thrust envelopes is introduced.

Original languageEnglish (US)
Article numberIAC-19_C1_2_8_x52768
JournalProceedings of the International Astronautical Congress, IAC
StatePublished - 2019
Externally publishedYes
Event70th International Astronautical Congress, IAC 2019 - Washington, United States
Duration: Oct 21 2019Oct 25 2019


  • Fuel-optimal
  • Gravity assist
  • Homotopy
  • Hybrid optimization
  • Low-thrust

ASJC Scopus subject areas

  • Aerospace Engineering
  • Astronomy and Astrophysics
  • Space and Planetary Science

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