Syllabus: Space technology
- Near side refers to the portion of the moon visible to us (about 60%). 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.
- The ‘new moon’ or when the moon is invisible from Earth is the time when the other ‘far side’ of the moon is bathed in sunlight and continues to receive light for nearly a fortnight.
- The ‘dark side’ is thus dark only in the sense that it was mysterious
- until the Soviet spacecraft Luna 3 in 1959 photographed it
- Astronauts aboard the Apollo 8 mission of 1968 were the first humans to see the far side of the moon.
The major difference between the two sides
- the near side is relatively smoother
- has many more ‘maria’ or large volcanic plains compared to the far side.
- Far side has huge craters, likely resulted from collisions with asteroids.
- the crust on the near side is thinner causing the volcanic lava in the lunar crust to fill up its craters.
- The resulting plains are far more conducive to space missions because they provide a relatively flat terrain for landers and rovers.
Chandrayaan-3 identified an area that had spots of 150 m spaces that would be conducive to a safe descent.
China’s Chang é-4 lander remains the only one to have successfully landed on the far side. This vehicle landed on the Von Karman crater situated within a larger 2,500 km wide crater called the South Pole Aitken basin.
What’s special about the Chandrayaan-3’s landing?
- managed to land Vikram the closest ever to the lunar South Pole.
- at 69.36 S and 32.34 E, it is about 600 km away from the South Pole.
- This 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.
- The Vikram lander didn’t exactly land in a shadowed region as it was necessary to shine sunlight on the lander and rover to charge their solar batteries to keep them powered.