Chandrayaan-2 Makes Groundbreaking Discovery: First Observation of Solar Coronal Mass Ejection Effects on Lunar Surface

Chandrayaan-2 Makes First Ever Observation Of Sun's Impact On Moon: ISRO

In August 2019, Chandrayaan-2 successfully achieved its planned elliptical orbit around the Moon. (File)

Chennai:

India's Chandrayaan-2 mission, which was launched in 2019, has achieved a significant scientific milestone by recording the first-ever observation of how the Sun's Coronal Mass Ejection (CME) affects the lunar surface, ISRO announced on Saturday.

This groundbreaking discovery provides valuable insights into the Moon's exosphere—its extremely thin atmosphere—and demonstrates how space weather phenomena impact the lunar environment.

The mission was initiated on July 22, 2019, from the Sriharikota launch facility using the powerful GSLV-MkIII-M1 rocket. Chandrayaan-2 carried a suite of eight scientific payloads and successfully entered lunar orbit on August 20, 2019.

Though communication with the Vikram lander was unfortunately lost during its descent attempt on September 7, the orbiter component has remained fully functional, maintaining its operational status in a 100 km x 100 km lunar orbit.

According to ISRO's official statement, the Chandra's Atmospheric Compositional Explorer 2 (CHACE 2) instrument aboard the orbiter has successfully documented the effects of solar Coronal Mass Ejections on the Moon's exosphere.

CHACE-2 was specifically designed to investigate the composition and distribution patterns of the lunar neutral exosphere and analyze its variability under different conditions.

Coronal Mass Ejections are powerful solar events where the Sun expels substantial amounts of its material, predominantly comprising Helium and Hydrogen ions, into space.

These solar phenomena have particularly pronounced effects on the Moon due to its lack of both atmosphere and global magnetic field—protective features that would otherwise shield its surface from direct solar impacts.

"CHACE-2 observations revealed a significant increase in the total pressure of the dayside lunar exosphere when the Sun's Coronal Mass Ejection impacted the Moon. The total number density—which measures the number of neutral atoms or molecules per unit volume—showed a remarkable increase of more than an order of magnitude," ISRO explained in its release.

"While theoretical models had previously predicted such effects, CHACE-2 onboard Chandrayaan-2 has provided the first direct observational evidence of this phenomenon." ISRO further reported that this rare opportunity to observe a CME directly impacting the Moon occurred on May 10, 2024, when multiple CMEs were ejected from the Sun toward the lunar surface.

The heightened solar coronal mass striking the Moon intensified the process of dislodging atoms from the lunar surface, releasing them into the Moon's exosphere and manifesting as increased total pressure readings in the sunlit lunar atmospheric layer.

Beyond advancing scientific understanding of lunar space weather interactions, this observation highlights important considerations for future lunar base development.

Engineers designing lunar habitats will need to account for these extreme solar events that temporarily but significantly alter the lunar environment before their effects dissipate, the statement concluded.