Moon mission gained from crash analysis: LPSC chief

Subject: Science and technology

Section: Space technology

Context:

The August 23 moon ‘landing scored by the Indian Space Research Organisation (ISRO) with its Chandrayaan-3 mission is also the story of how an efficient performance analysis helped the space agency bounce back in style from a setback.

Why did Chandrayaan-2 fail to achieve soft-landing?

It had five engines which were used to give the reduction of the velocity, which is called the r These engines developed higher thrust than what was expected.
- The extra thrust led to the accumulation of errors, which, in turn, compromised the stability of the lander during the “camera coasting phase’’ for the soft landing.
The craft had to make very fast turns. When it started to turn very fast, its ability to turn was limited by the software, thus unable to turn as required.
The lander, despite being close to the surface, increased its velocity as the landing site was quite far away.
- It was decelerating, but not fast enough to slow down to a speed of 2 metres/second (7.2 km/hr) that was required for a safe landing.

Committee and its recommendations:

Dr. V. Narayanan, who has headed the Liquid Propulsion Systems Centre (LPSC) since January 2018, had chaired the national-level expert committee which analyzed the reasons for the 2019 Chandrayaan-2 lander crash and recommended improvements that were incorporated in Chandrayaan-3.
- The Chandrayaan-2 mission, launched in July 2019 from Sriharikota, had performed normally until contact with its Vikram lander was lost at an altitude of 2.1 km amid its descent to the landing site.
The committee suggested improvements to:
- The software packages,
- The navigation,
- Guidance control systems,
- The propulsion mechanism,
- The powered descent scheme, and
- The Vikram lander system, among other things.
Its recommendations included:
- Enhancing the propellant margin in the spacecraft, and
- Strengthening the lander legs.
The entire software system was verified, validated and strengthened, because once the powered descent (to the lunar surface) starts, everything is autonomous and has to work with precision.

Liquid Propulsion Systems Centre (LPSC):

LPSC is the lead Centre for development and realization of earth-to-orbit advanced propulsion stages for Launch Vehicles and also the in-space propulsion systems for Spacecrafts.
The LPSC contributed four propulsion systems:
- The L110 core liquid stage and the C25 cryogenic upper stage for the LVM3 launch vehicle,
- One for the Propulsion Module and
- One for the Vikram lander which touched down on the lunar surface.