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Ancient Magma Ocean Discovered on Moon’s South Pole
Context:
Recent findings from India’s Chandrayaan-3 mission have unveiled groundbreaking insights into the Moon’s geological history.
More on News:
- The first analysis of soil samples near the Moon’s south pole suggests that its surface was once covered in molten magma.
- The analysis published in the journal Nature has focused on the data collected by Pragyan’s alpha-particle X-ray spectrometer.
- August 23 was declared India’s ‘National Space Day’ by the Indian Prime Minister, coinciding with the publication of the study.
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Mission Details
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Key Findings:
- Scientists believe that about 4.5 billion years ago, the Moon’s surface was initially covered by molten rock.
- As it cooled, denser minerals like olivine and pyroxene settled at the bottom, while lighter minerals rose to form the Moon’s upper crust.
- The upper crust is composed primarily of iron, magnesium, and sodium-rich rocks, while the lower crust consists of magnesium-rich rocks.
- This matches results from other missions, showing similar soil composition across the Moon’s equator and mid-latitudes supporting the lunar magma ocean (LMO) hypothesis.
- The rover’s close analysis provided detailed insights that orbiter missions might miss due to their limited ability to assess soil abundance and surface details.
- New data suggests that the asteroid impact that created the South Pole Aitken (SPA) Basin, the Moon’s largest and oldest basin, might have caused some mixing of the lunar crust’s layers.
- The Chandrayaan 3 landing site was situated 350 km from the SPA basin’s rim.
- The SPA basin, with a diameter of about 2,500 km—comparable to the distance between Delhi and Kochi—and a depth of 6.2-8.2 km, is thought to have formed 4.2-4.3 billion years ago from an asteroid impact near the lunar south pole.
Significance:
- First Polar Measurements: Chandrayaan-3 is the first mission to conduct in situ experiments at the Moon’s poles.
- Previous lunar missions focused on the equatorial and mid-latitude regions, making Chandrayaan-3’s data from the south pole particularly valuable.
Lunar Magma Ocean (LMO) Hypothesis
- The long-standing hypothesis is that the Moon was formed from debris resulting from a colossal impact between Earth and a Mars-sized object named Theia.
- This cataclysmic event would have generated immense heat, causing the Moon’s surface to melt into a magma ocean. As the molten rock cooled, it solidified into the uniform layer of ferroan anorthosite observed.
Implications:
- The presence of magnesium, believed to be from deeper lunar layers ejected by the impact, supports the idea of material from deep within the Moon being scattered across the surface.
- The data collected could help with future missions aimed at discovering ice water on the Moon’s south pole, which is crucial for potential lunar bases.
Future Missions:
- India plans to launch another mission around 2025 or 2026 to collect lunar surface samples and bring them back to Earth for further analysis.
- Chandrayaan-4 and 5: The Indian Space Research Organisation (ISRO) plans future missions, with Chandrayaan-4 tentatively scheduled for 2027 and Chandrayaan-5 expected to be a joint mission with the Japan Aerospace Exploration Agency (JAXA).