Trajectory design and orbit maintenance strategy for the Earth 2.0 (ET) space mission

The Earth 2.0 (ET) space mission plans to deploy a satellite equipped with six transit telescopes and one microlensing telescope at Sun–Earth L2 halo orbit. The optimal launch window and halo orbit amplitude are analyzed to mitigate stray light interference. The transfer trajectory is optimized to minimize propellant consumption, with a set of orbital parameters obtained initially using backward shooting and refined via differential correction in a forward-design framework. Furthermore, an orbit maintenance strategy is developed, accounting for momentum wheel unloading and solar exclusion constraints. Numerical simulations confirm that the spacecraft can be successfully inserted into the target halo orbit and can maintain operations for more than eight years.