BENGALURU: India’s unmanned moon landing mission — Chandrayaan-2 — has finally stepped into
the lunar orbit on Tuesday at 9.02 am. Dr K Sivan, Chairman, ISRO, during an interaction with media persons, said, “The Lunar Orbit Insertion (LOI) manoeuvres was performed successfully on Tuesday morning using the onboard propulsion system for a firing duration of about 29 minutes. This manoeuvres precisely injected Chandrayaan-2 into an orbit around the Moon.”
The satellite is located in a lunar orbit at a distance of about 114 km at perilune (nearest point to the Moon) and 18,072 km at apolune (farthest point to the Moon), he added. A series of orbit-lowering manoeuvres in the next few days will bring the orbiter into a 100x100 km altitude orbit from pole to pole.
Sivan said, “We will have four more lunar burns — One at 1 pm on August 21, three more on August 28, August 30 and September 1. By this process, the orbit of Chandrayaan 2 will be reduced from 18,000 km to a 100x100 km circular orbit around the moon by September 1,” he said. Likening the events of September 2, to that of a bridegroom leaving his house, Sivan said, the lander will be separated from the orbiter.
The attention of the team which was on the propulsion system so far will also shift to the lander, as it separates from the orbiter. “On September 3, a small deorbit manoeuvre will be held for about 3 seconds to ensure all systems are normal,” he said.
Then, on September 4, the real deorbit manoeuvre will be held for about 6.5 seconds, he said. With this, the lander will be put in the orbit of 35 km perilune and 97 km apolune. The following three days, parameters of the lander will be checked to ensure the system is perfectly alright, Sivan added.
On September 7, at 1.40 am, a powered descent will start, and in next 15 minutes at 1.55 am, the lander will land at the site at 71 degrees south of the equator (of the moon) between two craters called Manzinus C and Simpelius N.
After landing on the lunar surface, two hours later, a ramp in the lander will touch the ground. About three hours and 15 minutes, the rover will start to move from the lander. And at four hours, the lander will touch moons surface, he said.
A 90-degree orbital inclination of Chandrayaan-2 necessary to the mission was achieved with the precise execution of both the Trans Lunar Injection, performed on August 14, and LOI manoeuvre held on Tuesday.