Chandrayaan-3 vs Chandrayaan-2: ISRO reveals what went wrong and what's been fixed

livemint.com:

Chandrayaan-3 is a follow-on mission to Chandrayaan-2 and its objectives are to demonstrate safe and soft landing on the lunar surface, roving on the moon, and to conduct in-situ scientific experiments. The Chandrayaan-3 Mission, which was launched on 14 July 2023, is the second attempt by the Indian Space Research Organisation (ISRO) to send a spacecraft to the Moon. Four years ago, ISRO made a similar attempt but things did not work out as per the plan.

ISRO's Chandrayaan-2 Mission failed in its lunar phase because its lander 'Vikram' crashed into the surface of the moon following anomalies in the braking system in the lander while attempting a soft landing on September 7, 2019. In the case of Chandrayaan-3, ISRO Chairman S Somanath 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, to transfer the spacecraft from horizontal to vertical direction is the "trick we have to play" here, he added.

"The velocity at the start 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. The significance of the Chandrayaan-3 mission, unlike its unsuccessful predecessor, is that the Propulsion Module has a payload -- SHAPE -- Spectro- polarimetry of HAbitable Planet Earth which is to study Earth from lunar orbit.