The lunar orbiter from India”s second moon mission, Chandrayaan-2, has successfully recorded the first direct observations of the effects of the Sun”s Coronal Mass Ejection (CME) on the Moon. This significant achievement was made possible by the Chandra”s Atmospheric Composition Explorer-2 (CHACE-2) payload aboard the orbiter.
On May 10, 2024, a series of CMEs were released by the Sun, providing a rare opportunity for these observations. The Indian Space Research Organisation (ISRO) reported that measurements from CHACE-2 indicated a notable increase in the total pressure of the dayside lunar exosphere, which is characterized as a very thin atmosphere. The observations revealed that the total number density of neutral atoms or molecules in the vicinity surged by more than an order of magnitude.
ISRO explained that this increase aligns with earlier theoretical models that anticipated such an effect, marking the first occasion that CHACE-2 has detected it. The agency further elaborated that the heightened amount of solar coronal mass striking the Moon facilitated the process of dislodging atoms from the lunar surface, thus releasing them into the lunar exosphere, which was observed as a rise in the total pressure in the sunlit lunar exosphere.
This groundbreaking observation is expected to enhance scientific understanding of the lunar exosphere and the effects of space weather on the Moon. ISRO emphasized that these findings not only advance knowledge about lunar conditions but also highlight potential challenges for future lunar bases. Architects designing these bases must consider such extreme events that can temporarily change the lunar environment until conditions return to normal.
Chandrayaan-2, which was launched in 2019, consists of an orbiter, a lander named Vikram, and a rover called Pragyan. The orbiter is equipped with seven payloads, including CHACE-2. However, during its attempt to land on the Moon”s surface, the Vikram lander lost communication with ground control.
