Key Takeaways
- Chandrayaan-2’s CHACE-2 instrument made first-ever observation of solar CMEs impacting Moon’s atmosphere
- During May 10, 2024 solar event, lunar exosphere pressure increased dramatically
- Neutral atom density rose by more than 10 times, confirming long-standing theories
- Findings have crucial implications for future lunar missions and habitat design
In a major scientific achievement, ISRO’s Chandrayaan-2 lunar orbiter has captured the first direct evidence of solar Coronal Mass Ejections (CMEs) affecting the Moon’s extremely thin atmosphere. The breakthrough observation confirms theoretical predictions about lunar space weather that had never been validated until now.
Unprecedented Solar Impact Detection
During a rare solar storm on May 10, 2024, a series of CMEs struck the Moon, causing the total pressure in the dayside lunar exosphere to surge significantly. ISRO scientists reported that the number density of neutral atoms and molecules increased by more than an order of magnitude – the first direct measurement of such an event.
The Chandra’s Atmospheric Composition Explorer-2 (CHACE-2) instrument aboard Chandrayaan-2 recorded these changes, providing crucial data about how solar activity transforms the lunar environment.
Why the Moon’s Atmosphere is Vulnerable
The Moon’s exosphere, classified as a surface boundary exosphere, lacks a global magnetic field that could offer protection from solar radiation. This makes it highly sensitive to space weather events like CMEs.
“The Earth’s Moon has a very thin atmosphere, which falls under the category of ‘exosphere’, implying that the gas atoms and molecules in the lunar environment rarely interact despite their coexistence,” ISRO explained. “The boundary of the exosphere is the surface of the Moon.”
Scientific Implications and Future Missions
The CME event enhanced the process of atoms being knocked off the lunar surface, temporarily altering atmospheric conditions. These findings, published in Geophysical Research Letters on August 16, 2025, advance our understanding of lunar space weather and its effects.
ISRO emphasized that the observations highlight challenges for future lunar exploration. “Lunar base architects need to account for such extreme events, which would temporarily alter the lunar environment,” the space agency concluded, noting these temporary changes must be considered in designing human habitats on the Moon.
The study provides vital insights for planning and developing protection systems against space weather events that could affect both equipment and human explorers.
