ISRO has revealed an innovative initiative related to the Propulsion Module (PM) of Chandrayaan-3. Originally developed to support the gentle landing of the Vikram lander and Pragyan rover in the lunar south polar region, the mission accomplished its key goals when the Vikram lander made a historic touchdown on the Moon on August 23rd.
The scientific instruments on the lander and rover operated continuously for one lunar day, meeting the mission goals.
Subsequently, the PM, responsible for transporting the lander from Geostationary Transfer Orbit (GTO) to the final lunar polar circular orbit, successfully separated the lander and operated the SHAPE payload.
ISRO’s Innovative Mission Extension
Having more than 100 kg of fuel still available in the Propulsion Module (PM) following a month of lunar orbit activities, ISRO opted to leverage it for further data collection and future mission demonstrations. The strategy entailed repositioning the PM to an appropriate Earth orbit to sustain observations of the SHAPE payload.
The first maneuver on October 9, 2023, raised the apolune altitude to 5,112 km, and subsequent adjustments targeted an Earth orbit of 1.8 lakh x 3.8 lakh km.
The Trans-Earth Injection (TEI) maneuver on October 13 marked the beginning of the return journey, with the PM making four Moon fly-bys before leaving the Moon’s sphere of influence on November 10.
As of November 22, the PM is orbiting Earth with a nearly 13-day period and a 27-degree inclination.
Safe Orbital Dynamics and Valuable Insights from Chandrayaan-3’s Propulsion Module
ISRO assures that, based on current predictions, there is no threat of close approach to operational Earth-orbiting satellites.
The SHAPE payload operations persist within Earth’s field of view, with specific maneuvers executed during a solar eclipse on October 28, 2023.
The return maneuvers of the PM have yielded valuable outcomes for future missions.
This includes the planning and execution of trajectory and maneuvers for returning from the Moon to Earth, the development of a software module for maneuver planning and its preliminary validation, planning and execution of gravity-assisted fly-bys, and ensuring the controlled end-of-life descent to avoid debris creation on the Moon’s surface.
The flight dynamics team at the UR Rao Satellite Centre/ISRO played a pivotal role in creating analytical tools for these operations.