Why did Chandrayaan-3 land on the near side of the moon?

Source: The post is based on the article “Why did Chandrayaan-3 land on the near side of the moon?”  published in The Hindu on 26th August 2023. 

What is the News?

The controlled descent of the Vikram lander of Chandrayaan-3 made it one of the closest approaches of a lunar mission to the moon’s South Pole.

However, like most of the lunar-landing missions before, Vikram too landed on the near side of the moon. 

Hence, China’s Chang’e 4 mission is the only lunar mission to have successfully landed on the far side of the moon.

What are the moon’s ‘near’ and ‘far sides’?

Near Side: It refers to the portion of the moon — about 60% — that is visible to us. It is always the same side that is visible from Earth because the moon takes the same time to rotate about its axis as it does to circle around the Earth

Far Side: It is also known as the dark side area of the moon. It is called the dark side as it is facing away from the Earth. In reality it is no darker than any other part of the Moon’s surface as sunlight does in fact fall equally on all sides of the Moon. 

– It is only ‘dark’ to us, as that hemisphere can never be viewed from Earth due to a phenomenon known as ‘Tidal Locking’.

– The ‘dark side’ was mysterious and its various topographical features were hidden until the Soviet spacecraft Luna 3 in 1959 photographed it and the Soviet Academy of Sciences released an Atlas of these images.

– Astronauts aboard the Apollo 8 mission of 1968 were the first humans to see the far side of the moon.

Is the dark side very different from the near side?

Firstly, the near side is smoother and has more large volcanic plains called ‘Maria’ compared to the far side. On the far side, there are large craters, likely from asteroid impacts.

Secondly, the near side has a thinner crust, which allows volcanic lava to flow and fill up craters over millions of years, creating flat plains. These plains make it easier for space missions as they offer a more even terrain for landers and rovers.

What is special about Chandrayaan-3 landing?

The Chandrayaan-3 mission, while still on the near side, has managed to land Vikram the closest ever to the lunar South Pole. The coordinates of Chandrayaan-3 at 69.36 S and 32.34 E make it about 600 km away from the South Pole.

The choice of being as close as possible to the South Pole was to get closer to a “permanently shadowed region” or where no sunlight ever reaches.

This would mean increasing the chances of encountering frozen water-ice along with several “interesting deposits” that can reveal more about the moon and its harvestable resources.