Chandrayaan-3 to undergo deboosting today | The process explained

The lander module — comprising Vikram lander and the Pragyan rover — is expected to undergo a "deboost" to place it in an orbit, where the "Perilune (the orbit's closest point to the Moon) is 30 kilometres and Apolune (farthest point from the Moon) is 100 km, from where the soft landing on the south polar region of the Moon will be attempted," ISRO sources told news agency PTI.

Emphasising the importance of low velocity or speed in Chandryaan-3 mission, ISRO Chairman S Somanath had said earlier that the most critical part of the landing is the process of bringing the velocity of the lander and that the ability to transfer the spacecraft from horizontal to vertical direction.

The "deboost" phase is among the different "Moon Centric Phase". After "deboost" phase, comes the "Pre-landing Phase", followed by "Landing Phase", "Normal Phase for Lander and Rover" annd "Moon Centric Normal Orbit Phase". The "deboost" phase was preceded by "Transfer Trajectory Phase", "Pre-launch Phase", "Launch and Ascent Phase and "Earth-bound Manoeuvre Phase".

The "deboost", schedule for Friday, comes after the lander module successfully separated from the Propulsion Module on Thursday. The Propulsion Module will continue its journey in the current orbit for months or years, while the Lander Module prepares for its final descent.

"This is the beginning and all further milestones have to be seen very carefully. We have crossed major milestones from the launch vehicle and after that the propulsion system (separation)...now really the match starts. These are the final overs we are talking about. I think it is a great moment. The whole world is waiting to see what Vikram will do and What Pragyan will come out and do... I am also enthusiastically waiting," Chandrayaan-I Project Director M Annadurai told PTI.

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, a lander module and a rover to develop and demonstrate new technologies required for inter-planetary missions.

Chandrayaan-3 entered into the lunar orbit on August 5, following which orbit reduction maneuvers were carried out on the satellite on August 6, 9, 14 and 16, ahead of separation of both its modules today, in the runup to the landing on August 23.

As Chandrayaan-3 moves closer towards the Moon day-by-day, all eyes are on the soft landing it is expected to make on the south pole of Moon on August 23.