The country’s first lunar mission in 2008 – Chandrayaan-1 – did not land on the lunar surface, but it carried out the first and most detailed search for water on the Moon using radars.
What is this mission all about?
Chandrayaan-2 (Moon vehicle 2) will attempt a soft landing near the little-explored south pole of the Moon.
The mission will focus on the lunar surface, searching for water and minerals and measuring moonquakes, among other things.
India is using its most powerful rocket, the Geosynchronous Satellite Launch Vehicle Mark III (GSLV Mk-III), in this mission. It weighs 640 tonnes (almost 1.5 times the weight of a fully-loaded 747 jumbo jet) and at 44 metres (144ft) is as high as a 14-storey building.
The spacecraft weighs 2,379kg (5,244lb) and has three distinct parts: an orbiter, a lander and a rover.
The orbiter, which has a mission life of a year, will take images of the lunar surface, and “sniff” the tenuous atmosphere.
The lander (named Vikram, after the founder of Isro) weighs about half as much, and carries within its belly a 27kg Moon rover with instruments to analyse the lunar soil. In its 14-day life, the rover (called Pragyan – wisdom in Sanskrit) can travel up to a half a kilometre from the lander and will send data and images back to Earth for analysis.
“India can hope to get the first selfies from the lunar surface once the rover gets on its job,” Dr Sivan said.
A new frontier for India’s space programme
By science writer Pallava Bagla
A soft landing on another planetary body – a feat achieved by just three other countries so far – would be a huge technological achievement for Isro and India’s space ambitions.
It would pave the way for future Indian missions to land on Mars and an asteroid. More importantly, it would open up the possibility of India sending astronauts to the Moon. India hopes to carry out a manned space flight by 2022.
India also wants to assert itself as a space power to be reckoned with – and national pride is riding high as it aims to hoist its flag on the surface of the Moon.
A successful mission to the Moon would also be a win for India’s ambitious space agency, which has had a string of successes recently.
In 2014, it successfully put a satellite into orbit around Mars, becoming only the fourth nation to do so. In 2017, India created history by successfully launching 104 satellites on a single mission, overtaking the previous record of 37 satellites launched by Russia in 2014.
All eyes are on Isro again. Global interest in India’s frugal Moon mission is peaking, according to Simonetta Di Pippo, director of the UN office of Outer Space Affairs.
“The mission’s studies of lunar topography, mineralogy, elemental abundance, the lunar exosphere, and signatures of hydroxyl and water ice will contribute to scientific progress for all of humankind,” she says.
The Indian space community is nervous and Dr Sivan says “there is churning in his stomach”.
“Unknown-unknowns can kill a mission, [although] no stone has been left unturned to understand all the complexities”.
How long is the journey to the Moon?
The launch is only the beginning of a 384,000km (239,000-mile) journey – the robotic craft is expected to land on the Moon some 54 days later on 6 or 7 September.
Isro chose a circuitous route to take advantage of the Earth’s gravity, which will help slingshot the satellite towards the Moon. India does not have a rocket powerful enough to hurl Chandrayaan-2 on a direct path.
“There will be 15 terrifying minutes for scientists once the lander is released and is hurled towards the south pole of the Moon,” Dr Sivan says.
He explains that those who had been controlling the spacecraft until then will have no role to play in those crucial moments. The actual landing, he adds, is an autonomous operation dependent on all systems performing as they should. Otherwise, the lander could crash into the lunar surface.
Earlier this year, Israel’s first Moon mission crash-landed while attempting to touch down.
Who is on the team?
Nearly 1,000 engineers and scientists have worked on this mission. But for the first time, Isro has chosen women to lead an interplanetary expedition.