ISRO Assistant Scientific Secretary Vivek Singh says lander Vikram is an intelligent spacecraft

India's moon lander Vikram that separated from its mothership Chandrayaan 2 will not be controlled from the ground during the final moments of its descent tonight on the southernmost part of the moon, a top officer of the Indians Space Research Organisation told NDTV.

"Fifteen minutes of terror". That's how the ISRO Chairman K Sivan adds perspective to the finale of the highly complex Chandrayaan 2 moon mission.

"Nothing will be controlled from the ground. The lander Vikram is an intelligent spacecraft. The landing success rate, however, is less than 50 per cent," ISRO Assistant Scientific Secretary Vivek Singh told NDTV, explaining the enormous challenge the space agency faces in soft-landing the Chandrayaan 2 mission on the lunar surface.

The success of the Chandrayaan 2 mission will make India the fourth country after the US, Russia and China to pull off a soft landing on the moon.

The lander Vikram and rover Pragyan's lifespan is 14 days. After that there will be another 14 days of darkness on the area of the moon where they are, and the temperature could dip to minus 170 degree Celsius. The Chandrayaan 2 orbiter's lifespan is estimated at one year, but it may keep working longer.

After a successful touchdown scheduled at 1:55 am and once the superfine moon dust settles down, the lander Vikram will eject the rover Pragyan at 4:40 am.

"Etched on the rear wheels of the rover are the Ashoka Chakra and the ISRO logo," Mr Singh told NDTV.

The rover will then send its first selfies and photos of the lander and the lunar surface.

Prime Minister Narendra Modi will watch moon landing live with schoolchildren from the ISRO centre in Bengaluru. He is likely to address the scientists at the mission control centre in the morning.

The Chandrayaan 2 lifted off from its launch pad at Andhra Pradesh's Sriharikota on July 23 on board the giant heavy-lift rocket GSLV Mark 3. India's space scientists had a narrow one-minute window for their second attempt at launching the moon mission, a week after the mission was aborted 56 minutes before lift-off.

The GSLV Mark 3 - ISRO's largest and most powerful rocket - is 44 metres long or as tall as a 15-storey building.