Resonance Orbit

Author: Tianjiang Says

Website: https://cislunarspace.cn

Definition

A resonance orbit is a periodic orbit whose orbital period has a rational ratio with the Moon's orbital period. In the DRO family, resonance relationships T/TM=m/nT/T_M = m/n (where TT is the DRO period, TMT_M is the Moon's orbital period, and m,nm, n are positive integers) define specific orbit configurations with distinct characteristics.

Common Resonance Ratios

ResonancePeriod RatioCharacteristics
1:1T=TMT = T_MSynchronous with the Moon, close to the Moon
2:1T=TM/2T = T_M/2Spacecraft completes 2 orbits per lunar orbit
3:1T=TM/3T = T_M/3Higher orbit, larger amplitude
4:1T=TM/4T = T_M/4Far from Moon, good energy characteristics

Significance for DRO Design

Resonance orbits play a special role in DRO mission design:

  • Predictable geometry: At resonance, the spacecraft-Moon configuration repeats regularly
  • Eclipse avoidance: Certain resonance ratios may minimize or avoid eclipses
  • Transfer design: Resonant orbits serve as natural waypoints for transfer trajectories
  • Orbit stability: Some resonance ratios correspond to particularly stable configurations

References

  • Chen Yuju. DRO Orbit Design and Control Research for Cislunar Space Situation Awareness[D]. 2024.