ISRO (Indian Space Research Organization) made a surprising announcement earlier this week about a new accomplishment by the Chandrayaan-3 Propulsion Module after the team managed to successfully return the propulsion module used by the spacecraft into a high orbit around Earth. This is a big deal and something only achieved by 3 countries before India (US, China and USSR).
This was not one of the planned missions for the module and was attempted when the team found that they still have over 100 kg of fuel in the PM available on the module for maneuvers. Its a credit to the precise planning and execution of the entire mission that the module still had extra fuel available for followup missions. So the orbit was modified over the course of a few months to move to an Earth orbit at about 1.54 lakhs kms (154,000 kms) allowing the module to complete an orbit every 13 days.
In order to continue SHAPE payload for Earth observation, it was decided to re-orbit the PM to a suitable Earth orbit.This mission plan was worked out considering the collision avoidance such as preventing the PM from crashing on to the Moon’s surface or entering into the Earth’s GEO belt at 36000 km and orbits below that. Considering the estimated fuel availability and the safety to GEO spacecrafts, the optimal Earth return trajectory was designed for October 2023 month.
First maneuver was performed on October 9, 2023 to raise apolune altitude to 5112 km from 150 km thus, increasing the period of orbit from 2.1 hrs to 7.2 hrs. Later, considering the estimate of available propellant, the second maneuver plan was revised to target an Earth orbit of 1.8 lakhs x 3.8 lakhs km. The Trans-Earthinjection (TEI)maneuver was performed on October 13, 2023. In thepost-TEI maneuver realized orbit, propulsion module made four Moon fly-bys before departing Moon SOI on November 10. Currently, propulsion module is orbiting Earth and crossedits first perigee on November 22nd with an altitude of 1.54 lakhs km. The orbit period is nearly 13 days with 27 deg inclination. The perigee and apogee altitude vary during its trajectory and the predicted minimum perigee altitude is 1.15 lakhs km. Hence as per current orbit prediction, there is no threats of close approach with any operational Earth orbiting satellites.
This test was a good way to prepare for future lunar missions where one of the mission parameters would be to bring back samples from the Moon to earth for study. The module’s expected lifetime was about 3 months and its already past that and still going on. Looking forward to finding out what other additional experiments we can run on it.
– Suramya
Source: Arstechnica.com: India reveals that it has returned lunar spacecraft to Earth orbit