BENGALURU: With all eyes on Chandrayaan 3, which is scheduled to soft land on the designated site on the Moon’s south pole at 18.04 hours IST tomorrow, space scientists say that there is absolutely no doubt that the Lander will land safely, but caution that Moon missions are no “child’s play”.
“ISRO has run several simulations and I am sure that we will achieve our mission (of safe landing). Controlling and bringing down the velocity of the Lander; from around 1.69 km per second to one to two meters per second is a very complex maneuver. After the initiation of the last command from the Earth station to lower it to the landing site at around 5.47 pm on August 23, the Lander’s final journey will be autonomous. It will be on its own,” said former ISRO chairman Madhavan Nair.
“Right now the Lander is still under manual control of ISRO. A set of commands will be initiated at 5.47 pm on August 23 after which the autonomous landing system (ALS) will start. Thereafter, we will be mere spectators. There is nothing that can be done from the Earth station thereafter.
ISRO has programmed the ALS with a set of possibilities to encounter any perceivable eventuality while landing. While descending the module is assisted by an altimeter, velocity metre and other sensors so as to land at a place that is free from boulders or craters. The removal of energy from the Lander is manifested in the reduction of velocity,” said an informed source.
Chandrayaan 3 is designed around 6 Sigma bounds which means the chances of failure are 1 in a million, the source added. The landing has been timed with sunrise on the Moon’s south pole for 14 Earth
days. “The calculation of sunrise has been done based on scientific observation of the Moon,” he said.
“The Lander Module has an inbuilt ‘salvage mode’ which will help it land even if everything goes wrong,” said Aerospace Scientist Prof Radhakant Padhi, Department of Aerospace & Centre for Cyber-Physical Systems, Indian Institute of Science. “A lot of improvements have been incorporated in Chandrayaan-3 after the Chandrayaan-2 failure.
We are 99.9% sure that it will land safely,” he said. “All possible deviations and failure modes are addressed, redundancies are provided and the systems under such conditions have been tested many times so this time (in comparison to Chandrayaan 2) confidence level is more. Still, unknown is by definition unknown,” said former ISRO scientist and Padma awardee Mylswamy Annadurai.