Safe Than Sorry: Know why ISRO may reschedule Chandrayaan-3 landing

Even though the Chandrayaan-3 mission is going extremely smoothly, one never knows when things might go haywire. The engineers at ISRO have a number of contingencies in place which should ensure that, unlike Chnadrayaan-2, Chandrayaan-3’s Vikram Lander, actually gets a soft landing this time.

One of those contingencies is postponing Chandrayaan-3’s landing date. Nilesh M Desai, who is the Director at the Center for Space Applications-ISRO in Ahmedabad, explained that the space agency will evaluate the lander’s position in relation to the Moon’s surface a couple of hours before the scheduled landing.

To postpone or not
About two hours before the touchdown sequence is supposed to start, ISRO’s scientists will do a final check, mainly to see if the designated landing zone is viable for a touchdown on that particular day. If things are good, they will continue with the landing process. Otherwise, they will need to reschedule it for August 27.

The scientist also noted that if they do decide to make the landing attempt on August 27, it will happen around 400-450 km away from the originally intended landing site set for August 23.

Desai further added, “If we determine that the lander’s position isn’t suitable for landing, we’ll push the attempt to August 27. However, our first preference is to try for the landing on August 23.”

Things going well so far
The Vikram Landing module has performed so well, that it hasn’t used much of the emergency fuel that it had carried. In total, it is still carrying about 150 kg of extra propellant, which it might not need if things go as per plan, and the Vikram Lander module, touches down on the Moon on August 23, at 6:04 PM IST.

But because landing on the south pole of the Moon is something that hasn’t been done successfully, yet, a lot of things can go wrong.

Issues with the landing zone
The polar regions of any planet or its natural satellites have a peculiar gravitational pull. Magnetic fields also behave in an unusual way. Besides this, there is also the possibility that the topography of the place where Vikram is scheduled to land may be rendered unsuitable for some reason, all of a sudden.

Although ISRO has calculated for every possibility and contingency that may come up, they will need to make a last-minute check, even before the start the landing sequence. During this check, there is always a possibility that some new information may come up that may throw a spanner in the works.

Plus, the Moon has a lot of seismic activity. Moonquakes are not only a real thing, but they are also a very common occurrence on the lunar surface. The area where the Vikram Lander is supposed to touchdown, the Proposed Landing Site, or PLS, has had some moonquakes, but not severe ones.

Then there is extreme cold to worry about. Vikram Lander’s PLS is estimated to be at a temperature of -300 degrees Fahrenheit. This may severely impact Vikram’s ability to effectively land on the surface of the moon.

Issues with Vikram Module and its approach angle
Although the Vikram Module and all other aspects of the Chandrayaan-3 has gone extremely smoothly, there is always a chance that something goes off for a moment that puts ISRO in a position where it will have to rethink its landing strategy.

The most important element for tomorrow’s landing will be the Vikram Lander’s position, in relation to the Moon and where ISRO plans to land it. In case it does not align in a manner that is suitable for the landing, ISRO may have to postpone the touchdown.

Other technical issues
Russia’s Luna-25 had some communications issues with Roscosmos because of which it crashed onto the moon. Although the chances of Chandrayaan-3 crashing ont the Moon are slim, it may still face some issues with communications, because of the Moon’s poles and the magnetic fields around it. As a result, some technical glitches may come up.

Because of this, the Vikram landing module, may over shoot the position where it changes its orientation and starts slowing down. In such a case, ISRO would prefer to have Vikram land at some other spot.

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