The Propulsion Module (PM) of Chandrayaan-3 has been transferred from lunar orbit to Earth orbit.
On Monday, ISRO announced that the PM of Chandrayaan-3 was shifted from an orbit around the Moon to an orbit around Earth in yet another novel experiment, similar to the hop experiment on the Vikram Lander.
“Transporting the Lander module from GTO to the ultimate lunar polar circular orbit and separating the Lander was the primary goal for the PM. Spectro-polarimetry of HAbitable Planet Earth (SHAPE) payload in the PM was also carried out after separation. During PM’s mission, it was originally intended to operate this payload for roughly three months, according to an update from ISRO.
“The precise orbit injection by LVM3 and optimal earth / lunar burn maneuvers, resulted in the availability of over 100 kg of fuel in the PM after over one month of operations in the lunar orbit. It was decided to use the available fuel in the PM to derive additional information for future lunar missions and demonstrate the mission operation strategies for a sample return mission,” the space agency added.
ISRO said that 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,” ISRO said.
According to an update on the PM, ISRO stated that the first manoeuvre was carried out on October 9, 2023, raising the apollune altitude from 150 km to 5112 km, extending the orbit’s duration from 2.1 hours to 7.2 hours. Later, the second manoeuvre plan was changed to aim for an Earth orbit of 1.8 lakhs x 3.8 lakhs kilometres, taking into account the estimated amount of fuel available.
On October 13, 2023, the Trans-Earth Injection (TEI) manoeuvre was executed. Before leaving Moon SOI on November 10, the propulsion module completed four flybys of the Moon in the post-TEI manoeuvre realised orbit. The propulsion module is currently in orbit above the Earth and reached its first perigee on November 22 at a height of 1.54 lakh km. The orbit has a 27 degree inclination and a period of over 13 days. 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.
“As per plan, SHAPE payload is being operated whenever Earth is in its field of view. Also, a special operation of the SHAPE payload was carried out on October 28, 2023 during a Solar Eclipse.The Shape payload operations will continue further,” ISRO said.
The space agency further stated that an analysis tool for this operation has been developed from first principles by the flight dynamics team of the UR Rao Satellite Centre/ISRO, and it is being validated through the return manoeuvres conducted for the Chandrayaan-3 PM.
Recall that the main goals of the Chandrayaan-3 mission were to conduct tests with the equipment on Vikram and Pragyaan and to show soft landing close to the lunar south polar zone.
On July 14, 2023, the spacecraft was launched from SDSC, SHAR, aboard the LVM3-M4 vehicle. The momentous landing of the Vikram Lander on August 23 was followed by the deployment of the Pragyan rover. In accordance with the mission life, the scientific instruments on board Lander and Rover were run nonstop for a single lunar day. The mission objectives of Chandrayaan-3 have been completely met, said ISRO.
The Chandrayaan-3 consists of an indigenous Lander module (LM), Propulsion module (PM) and a Rover with an objective of developing and demonstrating new technologies required for Inter planetary missions. The Lander will have the capability to soft land at a specified lunar site and deploy the Rover which will carry out in-situ chemical analysis of the lunar surface during the course of its mobility. The Lander and the Rover have scientific payloads to carry out experiments on the lunar surface. The main function of PM is to carry the LM from launch vehicle injection till final lunar 100 km circular polar orbit and separate the LM from PM. Apart from this, the Propulsion Module also has one scientific payload as a value addition which will be operated post separation of Lander Module.
ISRO added added that the following are the main outcome from the return maneuvers carried out on PM related to future missions:
1.Planning and execution of trajectory and maneuvers to return from Moon to Earth.
2.Development of a software module to plan such a maneuver and its preliminary validation.
3.Planning and execution of a gravity assisted flyby across a planets/ celestial body.
4.Avoiding uncontrolled crashing of the PM on the Moon’s surface at the end of life of PM thus meeting the requirements of no debris creation.
The Chandrayaan-3’s Propulsion Module (PM) has been moved from Lunar orbit to Earth’s orbit. ISRO said that in another unique experiment, like the hop experiment on the Vikram Lander, the PM of Chandrayaan-3 was moved from an orbit around the Moon to an orbit around Earth.
ISRO said that in order to continue SHAPE payload for Earth observation, it was decided to re-orbit the PM to a suitable Earth orbit.
Updating on the PM, ISRO said that the 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.
