Explained: The Role Sun Will Play In Chandrayaan-3's Landing On Moon

In less than an hour, India will make history by launching its third moon mission, called Chandrayaan-3, to explore the lunar surface. It is a follow-up mission to Chandrayaan-2 and will land on the south pole of Earth's natural satellite after a 40-day journey. According to Indian Space Research Organisation (ISRO), the soft-landing has been planned according to the availability of sunlight. This has been done since solar panel has been added to the lander. ISRO chief S Somanath told news agency PTI that the additional solar panels will ensure that the lander generates power no matter how it lands.

"The sunlight is very important. That is why the landing has been planned when sunlight is available. It is crucial that it stays for the day so that you can charge the solar panels and the rover can go around," Annapurni Subramaniam, Director of the Indian Institute of Astrophysics in Bengaluru, told NDTV.

The module will approximately take six weeks to reach the moon around August 23. "The date is decided based on when the sunrise is on the moon; it will depend on the calculations, but if it gets delayed, then we will have to keep the landing for the next month in September," Mr Somanath had said last week.

ISRO has made several changes to Chandrayaan-3, based on the lessons learnt from the failure of Chandrayaan-2 that failed in September 2019.

Several scenarios including engine failure, sensor failure, calculation failure, and algorithm failure were examined and measures developed to counteract them.

"We have added new instruments to handle failures, new algorithms to handle off-nominal situations, new approaches to soft land in case of not-availability, any such measurements and total uncertainty," said Mr Somanath.

Another difference is the apparatus on the orbiters. While the Chandrayaan-2 orbiter carried 9 instruments, the new orbiter will have a lone in-situ instrument: Spectro-polarimetry of habitable planet Earth (SHAPE).

India's space programme has grown considerably in size and momentum since it first sent a probe to orbit the moon in 2008.