KOCHI: As the Isro centres are gearing up for the second Moon mission Chandrayaan-2 in July, they are focussed on the challenges of soft landing, ensuring trajectory accuracy while navigating long distance in extreme temperature and gravitational pull.

"Isro centres are trying to meet the challenges of Chandrayaan-2 launch during the window period July 9 to July 16. Chandrayaan-2 will perform a series of Trans lunar injection (TLI) burns for raising its level to reach the vicinity of Moon's orbit. Expected landing is on September 6. Soft landing is the most challenging part, while covering large distance influenced by non-uniform gravity of Earth and Moon. Further details will be presented at the press briefing," Isro chairman K Sivan told TOI on Monday.

Distance to the moon is about 3.844 lakh kilometre. Ensuring trajectory accuracy while navigating such large distance poses many challenges as trajectory is influenced by non-uniform gravity of the Earth and Moon, gravitational pull of other astronomical bodies, solar radiation pressure and the Moon's orbital motion, scientists at Vikram Sarabhai Space Centre (VSSC) said. Chandrayaan -2 will be launched on board the launch vehicle GSLV-MK III developed at VSSC.

To meet the challenge of soft landing on Moon's orbit, on-board Navigation Guidance and Control (NGC) and Propulsion system has to work in unison autonomously and automatically. Landscape features of the landing site should not result in a communication shadow area. In deep space at large distance, amidst heavy background noise, radio signals will be weak which needs to be picked up by large antennas, VSSC scientist said.

To reach the Moon's orbit, Chandrayaan-2 will perform a series of TLI burns for raising its level successively. Chandrayaan 2 on-board thrusters will fire precisely to reduce its velocity to reach lunar surface. Lunar surface is covered with craters, rocks and dust. Firing of on-board engines close to the lunar surface, results in backward flow of hot gases along with dust. Lunar dust is minute and hard pointed. Its negative charge makes it stick to most surfaces causing disruption in deployment mechanism and it's a challenge to ensure the performance of solar panel and NGC sensors. Lunar surface has extreme surface temperature variations and is hard vacuum, which makes it a hostile environment for lander and rover operations.

