Chandrayaan-3, India’s third lunar mission, is scheduled to undergo a critical operation around the Moon on August 16. According to the Indian Space Research Organisation, it will lower the orbit by doing a critical maneuver to 100 kilometers above the Moon's surface.
The critical operation on August 16 will involve lowering the orbit of the lander Vikram from an initial altitude of 150 kms to 100 kms. This will be done in a series of steps, with the lander firing its thrusters to gradually reduce its altitude.
The operation is scheduled to begin at 8:30 AM IST on August 16 and is expected to take about 3 hours.
The Orbit circularisation phase began on August 14 and precise maneuver performed achieved a near-circular orbit, ISRO said. "Orbit circularisation phase commences. Precise maneuver performed today has achieved a near-circular orbit of 150 km x 177 km," ISRO said in a tweet on Monday.
Post its launch on July 14, Chandrayaan-3 entered into the lunar orbit on August 5, following which two orbit reduction maneuvers were carried out on August 6 and 9.
After the next maneuver on August 16, the lander is expected to undergo a "deboost" (the process of slowing down) and make a soft landing on the south polar region of the Moon on August 23.
Last week, ISRO Chairman S Somnath had said the most critical part of the landing is the process of bringing the velocity of the lander from 30 km height to the final landing, and that the ability to transfer the spacecraft from horizontal to vertical direction is the "trick we have to play" here.
He said, "the velocity at the starting of the landing process is almost 1.68 km per second, but this speed is horizontal to the surface of the moon. The Chandrayaan 3 here is tilted almost 90 degrees, it has to become vertical. So this whole process of turning from horizontal to vertical is a very interesting calculation mathematically. We have done a lot of simulations. It is here where we had the problem last time (Chandrayaan 2)."
The soft landing of the Chandrayaan-3 mission on the Moon's south pole is scheduled for August 23. The lander Vikram and the rover Pragyan will be placed on the Moon's surface in the Manzinus C crater, which is located in the south polar region.
The soft landing process of the Chandrayaan-3 mission is a delicate operation that requires precise control and navigation. The lander Vikram will separate from the propulsion module and enter a 100 km x 30 km orbit. At around 30 km altitude, the lander will use its thrusters to navigate down to the lunar surface.
If successful, it will make India the fourth country to successfully soft land on the Moon. It will also be the first time that India has attempted to soft land on the Moon in the south polar region.
Chandrayaan-3 is a follow-on mission to Chandrayaan-2 to demonstrate end-to-end capability in safe landing and roving on the lunar surface.
It comprises an indigenous propulsion module, lander module, and a rover with an objective of developing and demonstrating new technologies required for inter-planetary missions.