Bengaluru, Aug 20 India's space agency ISRO is bracing for the next crucial manoeuvre on September 2 when lander Vikram will be separated from the Chandrayaan-2 mission orbiter for its soft-landing in the wee hours (1.55 a.m.) of September 7, a top official said on Tuesday.

"Our next challenge before landing near the lunar south pole on September 7 is the separation of lander Vikram from the orbiter on September 2, as the manoeuvre involves complex navigation over 100km above the Moon's surface," state-run ISRO Chairman K. Sivan told reporters here.

As the 2.4-tonne unnamed box-shaped spacecraft (orbiter) rotates at 90 degrees over the Moon, on-board engines will be fired on September 2 to separate Vikram from the top of it and lower it to orbit around 100 x 30km above the lunar surface for soft-landing near the south pole on September 7.

"As we have succeeded in inserting the orbiter into the lunar orbit at an inclination of 88 degrees and 114km x 18072 km orbit above its surface earlier in the day through complex 29-minute manoeuvres, preparations are underway for the next exercise on Friday afternoon for stabilising the orbiter at 90 degree inclination and 100km over the Moon from 114km currently," a space official told IANS.

The insertion has enabled the spacecraft to capture the lunar orbit by gravitational pull and go around the Moon.

In the run-up to the separation, the orbiter will go through a series of complex manoeuvres to enter its final orbit passing over the lunar poles about 100km above its surface.

"Till Vikram lands on the Moon with rover in it, it will also orbit around the Moon, lowering gradually its altitude with reduced velocity (speed) for soft-landing on September 7," said the official.

The Chandrayaan-2 spacecraft will continue to orbit around the Moon for over a year, charging and keeping all its robotic instruments active through its solar panels and conduct various experiments.

There will be four more manoeuvres till September 2 to reduce the orbit's speed and lower its altitude. On September 4, a six-second manoeuvre will be done on the lander to check its health and functions.

"We will also check the systems on-board the lander for three days from September 4-6 for its final descent on September 7 at 1.55 a.m. Indian time," added Sivan.

For rolling Pragyan out of Vikram two hours after its landing, a ramp will be taken out of it for sliding the rover onto the Moon's surface four hours later.

Vikram's solar panels will be deployed for activation three hours after its landing.

Soon after the landing, Vikram and Pragyan will begin a series of tests which will be a technological achievement.

"The implications of the mission are huge, as we will benefit from finding of new alloys, new discoveries and breakthroughs," asserted Sivan.

The ambitious Rs 978-crore second Moon mission with a lander and rover was launched on-board GSLV Mark-III from the state-run ISRO's rocket port at Sriharikota in Andhra Pradesh off the Bay of Bengal on the East Coast, about 80km north of Chennai.

Lander separation will be crucial'