Chandrayaan-3 Propulsion Module Completes Unprecedented Shift from Lunar to Earth Orbit

In a remarkable feat, the Indian Space Research Organisation (ISRO) announced on Monday the successful relocation of Chandrayaan-3's Propulsion Module (PM) from its original lunar orbit to Earth's orbit. This groundbreaking maneuver, reminiscent of the hop experiment conducted on the Vikram Lander in a previous mission, marks a significant milestone in the field of space exploration.

The primary objective of the PM was to transport the Lander module from Geostationary Transfer Orbit (GTO) to the final lunar polar circular orbit and facilitate its separation. Following the separation, the Spectro-polarimetry of the Habitable Planet Earth (SHAPE) payload in the PM was activated, initially planned for a three-month operation during the PM's mission life.

Unexpectedly, after over one month of operations in the lunar orbit, the PM had a surplus of over 100 kg of fuel. ISRO made the strategic decision to utilize this surplus fuel to gather additional information for future lunar missions and demonstrate mission operation strategies for potential sample return missions.

To sustain the Earth observation capabilities of the SHAPE payload, ISRO decided to re-orbit the PM to a suitable Earth orbit. The mission plan, developed with precision to avoid collisions, targeted an optimal Earth return trajectory for October 2023. Safety measures were incorporated to prevent the PM from crashing onto the Moon's surface or interfering with Earth's geostationary orbit belt.

Updates on the PM's maneuvers revealed that the first maneuver on October 9, 2023, successfully raised the apolune altitude from 150 km to 5112 km, extending the orbit period from 2.1 hours to 7.2 hours. Subsequent maneuvers were adjusted based on estimated propellant availability, ultimately targeting an Earth orbit of 1.8 lakh x 3.8 lakh km.

As of November 22, 2023, the PM completed its first perigee with an altitude of 1.54 lakh km, maintaining an orbit period of nearly 13 days with a 27-degree inclination. ISRO reassured that, based on current orbit predictions, there are no threats of close approaches to operational Earth-orbiting satellites.

The SHAPE payload continues to operate whenever Earth is within its field of view, showcasing its capabilities, including a special operation during a solar eclipse on October 28, 2023.

ISRO's successful repositioning of Chandrayaan-3's Propulsion Module signifies a significant leap forward in space exploration, showcasing adaptability and strategic planning. As the SHAPE payload continues its Earth observation operations, the Chandrayaan-3 mission sets a promising precedent for upcoming lunar missions and interplanetary exploration.

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