Chandrayaan-3’s Landing on the Moon’s Near Side
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Chandrayaan-3’s Landing on the Moon’s Near Side
Subject: Science and technology
Section: Space technology
Context
Chandrayaan-3’s Vikram lander executed a controlled descent, achieving one of the closest approaches to the moon’s South Pole, enhancing its scientific potential.
Moon’s Near and Far Sides:
- The moon’s near side (60% visible) always faces Earth because the moon takes the same time to rotate about its axis as it does to circle around the Earth.
- The “dark side” is not permanently dark; it receives sunlight during the “new moon” phase.
- The far side was revealed by Luna 3 in 1959 and seen by Apollo 8 astronauts in 1968.
Near vs. Far Side Differences:
- The near side is smoother with volcanic plains (“maria”).
- The far side features large craters from asteroid impacts.
- The thinner crust on the near side allowed volcanic lava to fill craters, creating flat plains ideal for landers.
- Chang’e 4 is the only mission to land on the far side.
- Von Karman crater, situated within a larger 2,500 km wide crater called the South Pole Aitken basin
| Aspect | Near Side | Far Side |
| Visibility from Earth | Visible from Earth, “front” side | Not visible from Earth, “back” side |
| Crater Distribution | Relatively smoother, maria present | More rugged, higher density of craters |
| Thickness of Crust | Generally thinner crust | Thicker crust |
| Highland vs. Maria | More lunar maria | More lunar highlands |
| Radio Signals | Direct communication possible | Requires relay satellites for coverage |
| Impact Basins | Several large basins present | Also contains significant impact basins |
| Geological Variations | Varied geology due to maria and highlands | Focused on highland terrains and older, densely cratered areas |
| Exploration | Explored by humans (Apollo) and robots – Chandrayan-3 & Orbitors | Primarily explored by robotic missions – Chang’e 4 Mission (China) & Orbitors |
Chandrayaan-3’s Special Landing:
- Chandrayaan-3’s Vikram landed close to the lunar South Pole (69.36 S, 32.34 E), about 600 km away from the South Pole.
- Aimed for a “permanently shadowed region” rich in potential water-ice and resources.
- Balanced proximity to the pole for scientific exploration with the need for sunlight to power the lander and rover.
Reasons for Near Side Landing:
- Choosing the near side allowed continuous line-of-sight communication with Earth, crucial for real-time updates.
- Landing on the far side would require relay systems, causing delays and reorienting the Chandrayaan-2 orbiter’s orbit.
- Mission objectives guided the landing site selection.