Mission Planning for Very-Low-Earth-Orbit Technology Exploration of ELITE with Collision Avoidance Ability

Everything else being equal, operating at a very low Earth orbit (VLEO) gives better ground resolution compared to operating at higher altitudes. However, operating at a VLEO faces marked atmospheric drag and various other uncertain interference factors. In this paper, we describe a pioneering satellite named ELITE (Extremely Low-earth Imaging and Technology Explorer) for high-resolution imaging and solar activity observation in VLEO. ELITE is planned to launch to an altitude of 550 km (Sun-synchronous orbit), then maneuver to a VLEO within the range of 200 to 350 km, and maintain that altitude for a year in VLEO through electrical propulsion. To address the challenges of VLEOs, a multiphase altitude planning framework is proposed, covering 4 critical scenarios that account for atmospheric drag, solar activity forecasts, and the strict requirements of time delay integration imaging. This enables robust and energy-efficient altitude adjustment strategies for stable long-term operation. An atmospheric density model is also developed, integrating solar activity predictions, drag coefficient estimation, public datasets, and onboard measurements, and validated using real VLEO mission data. A risk-aware collision avoidance strategy based on a beta-distributed differential evolution algorithm is introduced to balance safety and fuel efficiency, ensuring fast convergence during different evolutionary stages. These innovations ensure that ELITE can successfully accomplish its VLEO mission objectives: a groundbreaking 0.5-m ground sampling distance in color and innovative measurements of ionospheric intensity and atomic oxygen in VLEO. Our mission planning confirms ELITE’s capability to accomplish its missions, marking an important milestone in the field of VLEO satellites.