Why did the Chandrayaan 2 mission fail?

The spacecraft was launched on its mission to the Moon from the second launch pad at the Satish Dhawan Space Centre on 22 July 2019 at 2.43 PM by a GSLV Mark III. The craft reached the moon's orbit on 20 August 2019 and began orbital positioning manoeuvres for the landing of the Vikram lander. Vikram and the rover were scheduled to land on the near side of the Moon, in the south ploar region at a latitude of about 70° south on 6 September 2019.

Orbiter: The Orbiter will observe the lunar surface and relay communication between Earth and Chandrayaan 2's Lander — Vikram.

Vikram Lander: The lander was designed to execute India's first soft landing on the lunar surface.

Pragyan Rover: The rover was a 6-wheeled, AI-powered vehicle named Pragyan, which translates to 'wisdom' in Sanskrit.

Reason of failure of Chandrayaan 2

 

 We could observe that the lander deflected from the trajectory that it was supposed to travel. The speeds had to be reduced to 7km/hr from 21,000km/hr. One nanosecond delay and the lander Vikram deviated from the desired path.

 

  1. The lander is orbiting in vacuum (very very very thin compared to earth). It needs to be slowed down and the only way to slow it down is to fire the thrusters in a direction opposite to orbital direction so that burning fuel exerts pressure on the lander in the opposite direction to slow it down.
  2. Slowing it down from orbit will mean that we now have a projectile motion. The lander will fall to moon like how a bullet fired on earth will eventually fall on earth.
  3. I am not sure how many of you noticed that the images showed the actual orientation/inclination of the lander w.r.t moon and at one point, it was spinning.
  4. The lander had to adjust its thrusters to fire in such a way that it reaches a point above the moon’s surface where it is actually vertically aligned like how the space-X reusable rockets come back to earth by aligning vertically and slowly descending with the same alignment. (With the thrusters firing and the lander not properly aligned, the trajectory went awry)
  5. If it can be vertically aligned (starting from an initial horizontal position) with its thrusters firing, it can hover for some time and descend slowly. This alignment is what I feel did not happen.

 

Only the lander failed to land safely, the orbiter completed its mission successfully. It should not be termed as a failure though, as Narendra Modi said, “There is no failure in Science. There are only experiments and efforts and learnings!”