Impact of a Coronal Mass Ejection on the Lunar Exosphere 

Syllabus: GS3 / Science and Technology

Context

• The Chandrayaan-2 mission has made the first-ever observation of the effects of the Sun’s Coronal Mass Ejection (CME) on the Moon using its onboard scientific instruments.

About the observation

• The finding was made by Chandra’s Atmospheric Composition Explorer-2 (CHACE-2), a payload onboard Chandrayaan-2’s orbiter.
• CHACE-2 recorded a sharp rise in total pressure and molecular density in the Moon’s sunlit exosphere.
  • CMEs are the events when the Sun ejects significant quantities of its building material, comprising mostly Helium and Hydrogen ions.

Composition of Lunar Exosphere

• The Moon’s atmosphere is extremely thin, classified as an exosphere, implying that the gas atoms and molecules in the lunar environment rarely interact despite their coexistence. 
• The boundary of the exosphere is the surface of the Moon and hence the Moon’s exosphere falls under the category of ‘surface boundary exosphere’.
• The lunar exosphere is formed by processes such as:
  • Solar radiation,
  • Solar wind (ions of hydrogen, helium, and trace heavier elements), and
  • Meteorite impacts that release surface atoms into space.
• Unlike Earth, the Moon lacks a magnetic field, making it directly exposed to CMEs.

Significance of the observation

• It provides valuable insight into lunar exospheric dynamics and space weather effects on airless celestial bodies.
• Enhances understanding of Sun–Moon interactions, contributing to better space weather prediction models.
• Provides critical knowledge for future lunar missions and habitats, especially for human presence on the Moon by 2040.
• Reinforces India’s growing capability in planetary science and space environment monitoring.

Source: AIR