Eclipse avoidance in TianQin orbit selection

Understand

In future geocentric space-based gravitational-wave observatory missions, eclipses due to passing through the Moon's and Earth's shadows can negatively impact the sciencecraft's thermal stability and steady power supply.

• The occurrence should be reduced as much as possible in orbit design.
• In regard to TianQin's circular high orbits, we tackle the combined challenges of avoiding eclipses and stabilizing the nearly equilateral-triangle constellation.
• Two strategies are proposed, including initial phase selection and orbit resizing to 1:8 synodic resonance with the Moon, where the latter involves slightly raising TianQin's preliminary orbital radius of $1\times 10^5$ km to $\sim 100900$ km.