ISRO Returns Chandrayaan-3 Prop Module To Earth Orbit As Lunar Return Tech Demo

The Indian Space Research Organisation (ISRO) has made a surprise announcement, announcing they have successfully brought the Chandrayann-3 Propulsion Module back to Earth orbit; as a demonstration of crucial technologies aimed at supporting future Indian lunar sample return missions.

The 2,145-kilogram propulsion module, a modified version of ISRO’s I-3K satellite bus, played a pivotal role in transporting the Chandrayaan-3 lander from its initial elliptical Earth orbit to a low lunar orbit. The module executed a series of maneuvers starting just a day after its launch on July 14, raising the apogee of its orbit and performing translunar and lunar orbit insertion burns. The lander separated from the module on August 17, successfully landing on the moon on August 23.

Following the lander's descent, the propulsion module remained in lunar orbit, where it operated a single instrument known as Spectro-polarimetry of Habitable Planet Earth (SHAPE) to observe the Earth. However, ISRO had not initially disclosed any plans to bring the module back to Earth orbit.

ISRO revealed that the decision to attempt the return was made after determining that the precision of the launch and earlier maneuvers had left more than 100 kilograms of propellant on the spacecraft.

The first maneuver for the return occurred on October 9, raising the high point in the orbit (apolune) from 150 to 5,112 kilometers.

A transearth injection maneuver on October 13 set the module on a trajectory that included four close approaches to the moon before leaving its sphere of influence on November 10.

The spacecraft entered a high Earth orbit, reaching its first perigee on November 22 at an altitude of 154,000 kilometers. The orbit period is nearly 13 days with 27 deg inclination.

The ISRO has mapped the spacecrafts orbit for the next year.

ISRO emphasized that these maneuvers were designed not only to bring back the propulsion module but also to derive additional information for future lunar missions and demonstrate mission operation strategies for a sample return mission. The agency, however, has not formally announced plans for such a mission.

While the next ISRO mission to the moon is the Lunar Polar Exploration Mission (LUPEX), a joint effort with the Japanese space agency JAXA, discussions within ISRO indicate a potential near-term lunar sample return mission.

Indian Prime Minister Narendra Modi set goals for the ISRO that included an Indian space station by 2035 and Indian crewed lunar landing by 2040, but did not discuss lunar sample return.

“The government of India has given us a very tight timetable for exploration in space. We need to have a sample return from the moon within about four years,” - Shri M. Sankaran, director of ISRO’s U R Rao Satellite Center

The return of the Chandrayaan-3 propulsion module to Earth orbit represents another significant step in ISRO's endeavors to achieve ambitious lunar exploration goals, including potential sample return missions.