Chandrayaan-3: Propulsion Module And Lander Module Gear Up For Their Separate Journeys As Spacecraft Completes Final Move

Chennai: India's ambitious Chandrayaan-3 spacecraft on Wednesday successfully underwent a fifth and final lunar-bound orbit manoeuvre, bringing it even closer to the surface of the Moon.

"Today's successful firing, needed for a short duration, has put Chandrayaan-3 into an orbit of 153 km x 163 km, as intended. With this, the lunar bound maneuvers are completed. It's time for preparations as the Propulsion Module and the Lander Module gear up for their separate journeys," ISRO said in a post on X (formerly Twitter).

Separation of the lander module from the propulsion module is planned for August 17, it said.

After separation, the lander is expected to undergo the process of slowing down to place it in an orbit, where the Perilune (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 on August 23, ISRO sources said.

This is most critical part of landing 

ISRO Chairman S Somanath recently 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.

"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)," Somanath explained.

Further, it has to be ensured that fuel consumption is less, the distance calculation is correct, and all the algorithms are working properly, he added.

Over five moves in the three weeks since the July 14 launch, ISRO had lifted the Chandrayaan-3 spacecraft into orbits farther and farther away from the Earth.