Chandrayaan-3 gets closer to moon, commences orbit circularisation phase

Chandrayaan-3 is just one step away from the lander getting separated as the spacecraft closes in on moon. Indian Space Research Organisation (ISRO) on Monday announced that the orbit circularisation phase was commenced and it has achieved a near-circular orbit of 150km x 177km.

"Orbit circularisation phase commences. Precise maneuvre performed today has achieved a near-circular orbit of 150 km x 177 km. The next operation is planned for August 16, 2023, around 0830 Hrs. IST," said ISRO.

On August 9, ISRO had guided Chandrayaan-3 to an orbit of 174km X 1,437 km. While on August 6, the spacecraft successfully underwent a planned orbit reduction manoeuvre. “The retrofiring of engines brought it closer to the moon's surface, now to 170 km x 4,313 km,” said ISRO. 

The lander and the rover will break away from the propulsion module after the last maneuver on Wednesday.

After the separation, 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.

ISRO chairman S. Somnath last week said that one of 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.

"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)," said Somnath.

"Extensive simulations have gone, guidance design have been changed, and a lot of algorithms have been put in place to make sure that in all these phases required dispersions are handled....to attempt to make a proper landing," he added.

The Chandrayaan-3 has successfully inserted into the lunar orbit two weeks back.

ISRO had informed that there will be three moon-bound manoeuvres before the landing module breaking away from the propulsion module.

Since the launch on July 14, ISRO has been lifting the Chandrayaan-3 spacecraft into orbits away from the Earth in over five moves.

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.