Chandrayaan-3 Reveals Energetic Plasma Environment Near Lunar South Pole

India’s Chandrayaan-3 mission has uncovered surprising details about the electrically active region just above the Moon’s south-polar surface. Direct measurements from the Vikram lander show that the near-surface plasma is far denser and more energetic than earlier remote estimates, offering new insights into the lunar ionosphere.

Plasma Formation And Solar Interactions

The Moon’s plasma environment arises from solar wind particles, photoelectric charging caused by sunlight and occasional entry into Earth’s magnetotail. These processes create a thin but dynamic ionised layer above the surface. Although electrically neutral overall, plasma responds strongly to electromagnetic forces, making it distinct from ordinary gases.

Key Findings From RAMBHA-LP Instrument

Chandrayaan-3’s Langmuir Probe at Shiv Shakti Point recorded electron densities ranging between 380 and 600 particles per cubic centimetre—significantly higher than values inferred from radio-occultation studies. The electrons also exhibited kinetic temperatures of roughly 3,000 to 8,000 Kelvin, indicating an unexpectedly energised plasma layer in the Moon’s southern high latitudes.

Variable Plasma Influenced By Lunar Orbit

The plasma density and energy fluctuated as the Moon moved through sunlight and into Earth’s magnetic tail. During dayside exposure, solar wind interactions dominated, while within the magnetotail, particle streams from Earth altered the plasma’s composition and behaviour. Findings also point to contributions from molecular ions, including those formed from carbon dioxide and water vapour, expanding the understanding of ionospheric chemistry.

Exam Oriented Facts

• Chandrayaan-3 provides first direct near-surface plasma measurements at the south pole.
• Electron densities measured: 380–600 cm³; temperatures: 3,000–8,000 K.
• Plasma varies with solar wind exposure and entry into Earth’s magnetotail.
• RAMBHA-LP was developed by the Space Physics Laboratory, VSSC.

Implications For Future Lunar Exploration

These measurements offer essential baseline data for missions operating near the south pole, where plasma conditions could affect communication systems, surface charging and instrument performance. By delivering direct observations, Chandrayaan-3 strengthens India’s contribution to global lunar science and advances understanding of the Moon’s electrically active environment.