The 90 degree challenge for Chandrayaan-2.

• Chandrayaan-2 is set for its historic soft landing on the moon on 7 September

• It was injected into the moon’s orbit on Tuesday. It would undertake four more manoeuvres to reach the final orbit around the moon

As Chandrayaan-2 prepares for its historic soft landing on the moon on 7 September, one of the biggest challenges for it would be to ensure that its orbit inclination is precisely on the mark, before it attempts touchdown on the moon.

It is for the first time that a space mission is attempting to land near the south pole of the moon, where no space mission has ever been before. The most recent moon mission by China landed near the equator on the far side of the moon, while the one from Israel could not achieve a successful landing.

Chandrayaan-2 was injected into the moon’s orbit early on Tuesday and would undertake four more manoeuvres to reach the final orbit of 100kms x 100 kms around the moon. The next crucial step would be performed on September 2, when Lander Vikram would separate from the orbiter. It will carry out a 3-second manoeuvre the next day to test if all systems onboard the Lander are normal. De-orbiting would be done on September 4 to bring down the Lander to an orbit of 35 X 97 kms.

Over the course of next three days, Isro will keep monitoring the functioning of the Lander. At 1:40 am on September 7, it will begin its powered descent. While its coming down, it will screen the landing site and compare it with the Isro images onboard.

Isro is using a new technology for soft landing using the five thrusters of the Lander for throttling the engine onboard. The Lander would have to decrease its velocity from 6km/second to zero in a controlled, but autonomous manner. All the image and altitude sensors have to work precisely to allow the Lander to make proper decisions.

Learning from Israel’s failed moon mission this April, Isro has also upgraded the sensor characterization onboard and made the module more autonomous to ensure less ground control to avoid any false decisions.

Lunar dust is another major concern as it could cover the Lander and impair its functions. To avoid this, scientists have automated the system to switch off all the four thrusters during landing with only the central thrusters on. This way, the plumes of dust would not cover the Lander and it can land smoothly.

As Chandrayaan-2 inches closer to the moon, the anxiety levels are building up among the scientists at Isro. The success rate for space missions for soft landing has only been 37% so far. But Isro is confident of pulling it through.

The landing near the South Pole would be critical, as countries across the world are vying with each other to fly their flags at the site. Chandrayaan-2 would also provide inputs to US-based National Aeronautics and Space Administration (NASA) for Artemis — its upcoming manned moon mission to the south pole of the moon. (Source: Livemint)