Video has captions
- CY2 lander had limited leeway in fixing issues, by design. CY3 has more and has landed itself, no assistance from base.
- CY2 lander had limited time to fix itself, apparently it was just a few seconds short of making it fine
In other words, it could perhaps correct itself in those many seconds but was allowed only small degrees of change.
The video provides an explanation for why India's Chandrayaan 2 lunar landing mission failed in 2019. The landing craft Vikram experienced issues during the camera coasting phase where instruments were being calibrated. Specifically, the engine thrust was higher than expected and thrust control couldn't be adjusted to correct the trajectory. As a result, errors accumulated and Vikram's trajectory deviated significantly from the planned path. For Chandrayaan 3, ISRO has implemented changes like adding instantaneous thrust control, increasing the allowed attitude change rate, and enlarging the landing zone to make the mission more robust to errors. The video offers an insightful technical look into what went wrong and how ISRO is addressing it for the next lunar mission.
What made them make that decision? Was it like "lets be as precise as we can because we want to get to the spot X because X is special" and thus "Lets let the software always compensate for any errors to get to X". I am assuming that even at this point they tested the software for extreme conditions. It is most likely that once this assumption was made the Software was built that way, i.e: "Lets test the Software can always correct for any issues to get to X with feedback(like thrust)". It trades off Safety for Accuracy(to hit X).
This time the idea was "Lets select a trajectory to X" but this time "We will let the software prioritize safety(altitude, speed and heading) to be within norm once we start descending towards X". And additionally "Not make any corrections if we are somehow too far off X if it exceeds safety limits". It trades off Accuracy(to hit X) for Safety.