In a groundbreaking achievement, the Indian Space Research Organisation (ISRO) has undertaken a distinctive operation, repositioning the Propulsion Module (PM) of Chandrayaan-3 from its lunar orbit to an Earth-centric orbit. This strategic shift comes after the PM successfully completed its primary objectives on the moon.
Confirming the PM’s triumph in ferrying the lander module from the Geostationary Transfer Orbit (GTO) to the final lunar polar circular orbit, ISRO executed a flawless separation as planned. Post-separation, ISRO activated the Spectropolarimetry of the HAbitable Planet Earth (SHAPE) payload within the PM. Originally slated for a three-month operation during the PM’s mission life, optimized orbital maneuvers left over 100 kg of fuel after over a month in lunar orbit.
Capitalizing on surplus fuel for extended missions, ISRO decided to utilize this opportunity to gather additional data for upcoming lunar missions and demonstrate operational strategies for future sample return missions.
To facilitate ongoing Earth observation through the SHAPE payload, ISRO strategically repositioned the PM to a suitable Earth orbit. The plan prioritized collision avoidance with the Moon’s surface and Earth’s Geosynchronous Equatorial Orbit (GEO) belt at 36,000 km and lower orbits.
The PM’s optimal return trajectory was carefully designed for October 2023, with precise maneuvers altering its altitude and orbit period, eventually transitioning it away from the Moon’s sphere of influence on November 10.
As of now, the PM orbits Earth, crossing its first perigee on November 22 at an altitude of 1.54 lakh km, with 13 days and a 27-degree inclination. ISRO assures that there is no threat to operational Earth-orbiting satellites based on orbit predictions.
In ongoing operations, ISRO continues to operate the SHAPE payload during Earth’s visibility, showcasing its capabilities by conducting a special operation during a solar eclipse on October 28, 2023.
ISRO’s flight dynamics team played a crucial role in developing analysis tools and software modules for trajectory planning and execution, gravity-assisted fly-bys, and ensuring the controlled termination of the PM’s life without debris creation.
Highlighting the significant achievements, ISRO outlined the primary results of the return maneuvers performed on the PM for future missions, including planning and executing the trajectory back from the Moon to Earth, creating software for this maneuver and validating it, performing a gravity-assisted fly-by around a planet or celestial body, and ensuring the controlled termination of the PM to prevent debris upon its end of life on the Moon’s surface.
The Chandrayaan-3 mission, launched on July 14, 2023, aimed to demonstrate a soft landing near the lunar south pole and conduct experiments via instruments on the ‘Vikram’ lander and ‘Pragyan’ rover. With a historic Vikram lander touchdown on August 23, the spacecraft has not only achieved its mission objectives but also paved the way for India’s continued advancements in space exploration and future lunar missions.