ISRO Chairman S Somanath said the orbiter will look for signatures of life on Earth.
A lot can happen in a day. And when it's a lunar day - equivalent to 14 Earth days - the possibilities expand. This is what Chandrayaan-3's lander and rover will seek to capitalise on in their short mission life of one lunar day when they make it to the surface of the Moon around the end of next month.
Loaded with instruments, the lander and rover will study the surface and atmosphere of the Moon. The orbiter - which was not supposed to have any payload - will turn its focus to Earth to look at signatures of life on the Pale Blue Dot so that it can aid in the search of exoplanets (planets beyond the solar system) that may support life.
In an exclusive interview with NDTV, Indian Space Research Organisation (ISRO) Chairman S Somanath said that the instruments on the lander and rover will be the same as the ones on their predecessors, which were part of Chandrayaan-2. The names of the lander and rover - Vikram and Pragyan - are also the same as the previous mission, in which some of the objectives could not be met because of a hard landing.
"The instruments on both the lander and rover are the same as what we flew last time. The mineral study or constituent element study of the surface of the Moon is one objective we want to look at. We want to also look at the low-height atmospheric characteristics and electrostatic characteristics of the Moon," said Mr Somanath.
"We would like to pierce a sensor into the surface of the Moon to a depth of almost 10 cm and measure the thermophysical characteristics of the Moon regolith (the layer of unconsolidated solid material covering the bedrock). So these are the types of observation capabilities that we have built into both the lander and rover," he added.
Asked whether ISRO will look at any signs of life of the Moon, Mr Somanath said that all the available knowledge indicates that there is no possibility of life on the Moon, and there is no instrument to look specifically for it. "But we are looking at the thermophysical and the static electric charge characteristic of the Moon. We are also looking at a seismological study," he said.
While Vikram and Pragyan go about their studies on the lunar surface, the orbiter will use a spectrographic instrument to look for signatures of life on Earth. The same signatures will then be used to look for signs of life on other Earth-like planets in the future.
Mr Somanath said exoplanets are of great interest to astronomers all over the world and many of them have been discovered, including around the stars that are relatively close to Earth.
"Today we do a certain amount of remote sensing of the atmosphere of those planets to understand the relative distance between the planet and the Sun. We find out the star's capability - what will be the likelihood of the temperature there? We look at the light coming through the atmosphere of a planet and then look to spectroscopically identify the structure of that atmosphere - whether water is present, whether oxygen is present," he said.
"So this is the extent of study today. But if you are able to do a similar observation for Earth and then use some correlation between this to the exoplanets, possibly we can say such and such planets have a high likelihood of having life similar to Earth. Of course. life could be in many other forms and it doesn't have to be like life on Earth. It may not be carbon- and oxygen-based,"
Chandrayaan-3 is scheduled to launch on Friday at 2.35 pm from the Satish Dhawan Space Centre in Sriharikota. The lander is expected to soft-land on the lunar surface on August 23 or 24.