The loss of a week due to the aborted launch of India’s second moon mission, Chandrayaan-2, on July 15 has not hampered the mission’s targeted landing date on the moon’s South Pole with ISRO aiming to make up for the lost time by adjusting the module’s Earth and Moon-bound phases.
The space agency is still aiming to put the Lander (Vikram) and Rover (Pragyan) on the lunar surface on September 7, just one day behind the earlier schedule, to ensure that the duo get their planned full schedule of operating for nearly 14 Earth Days by tweaking the Chandrayaan-2’s timelines in space when it travels from one phase to another. ISRO Chairman K. Sivan confirmed to The Hindu that the landing will be attempted on September 7.
One of the major challenges ISRO faced when the launch was aborted was to ensure that they got the current window of September 6-7 to land on the moon. This meant the team had to work backwards to make modifications to the mission, or as one ISRO official said do some reverse engineering. “Plus, there is always flexibility over the Earth-bound and Lunar-bound phases,” the official said.
Under the old plan, the soft-landing of Vikram and Pragyan was planned to be executed on Day 54 from the lift-off date. But with a ‘technical snag’ wrecking the plans, ISRO had to improvise or risk losing precious time for the mission.
The launch is now scheduled for 2.43 p.m. on Monday and the countdown began at 6.43 p.m. on Sunday.
As per the new timeline, the Earth-bound phase has increased by six days to 23 days; earlier it was 17. Under the old schedule, the Lunar Orbit Insertion (LOI) was supposed to have happened on Day 22, but now it will be on Day 30. The Lunar Bound Phase (LBN), which under the previous launch schedule was to have taken 28 days has now shrunk to just 13, between Day 30 and Day 42 after lift-off.
The Lander-Orbiter Separation will be executed on Day 43, while deboosting will be initiated on Day 44, with the powered descent of the Lander and Rover on Day 48 to the lunar surface. It is crucial for ISRO to land during this window, as the touchdown will be done at the high plain between two craters, Manzinus C and Simpelius N that will be at a point facing the Earth and would have started receiving sunlight by then.