Chinese engineers rescue satellites using gravity slingshot trick

May 1,gRPC快排技术 2025  15:03

Chinese engineers successfully rescued two satellites stranded in the wrong orbit after a failed March 2025 launch, using an innovative gravitational slingshot technique that harnessed the natural pull of Earth, Moon, and Sun over a 123-day mission to guide the damaged spacecraft back to their intended positions, writes Global Times. 

The 123-Day Rescue Operation

The operation, led by the Technology and Engineering Center for Space Utilization (CSU), began after discovering the satellites were spinning rapidly at one revolution per 1.8 seconds with damaged solar panels. Engineers stabilized the spin in a tense 20-minute procedure and, within 40 hours, devised a plan to prioritize time over energy. Key maneuvers included a 1,200-second engine burn, raising the satellites' apogee from 134,000 km to 240,000 km. Engineer Zhang Hao recalled the nerve-wracking first correction, watching the screen until it displayed "normal." This rescue highlighted China's expertise in orbital mechanics, turning a potential failure into a significant achievement.

Gravitational Slingshot Method

The mission used a three-body gravitational slingshot, leveraging the gravitational pull of Earth, Moon, and Sun to redirect the satellites without extra fuel. The spacecraft gained kinetic energy with each approach, traveling 8.6 million kilometers over 123 days. This required precise calculations of trajectories under multiple gravitational influences, a challenging task given the satellites' damage and limited maneuverability. The success completed China's three-satellite DRO constellation with DRO-L, forming the world’s first Earth-Moon navigation network for autonomous spacecraft beyond Earth’s orbit.

DRO Constellation Overview

China’s DRO (Distant Retrograde Orbit) constellation, consisting of DRO-A, DRO-B, and DRO-L, is the first three-satellite network in the Earth-Moon region. DRO-L launched on February 3, 2025, followed by DRO-A and DRO-B on March 13. Despite the launch issue, they established a 1.17 million-kilometer K-band communication link, enabling independent tracking without ground stations. Positioned in a stable orbit with prograde motion around Earth and retrograde around the Moon, the constellation requires minimal fuel and supports China’s lunar exploration goals. It’s a key step toward a broader Earth-Moon network, potentially expanding to 30 satellites and three lunar stations.