Chandrayaan-2 Makes Historic First Observation of Sun’s Coronal Mass Ejection Impact on Moon’s Exosphere

Understanding Chandrayaan-2 and Its Mission

Launched in July 2019, Chandrayaan-2 has been India’s second lunar exploration effort, orbiting the Moon with a suite of scientific instruments. While the Vikram lander’s communication was lost during its attempted landing, the orbiter continues to perform groundbreaking science from a stable 100 km x 100 km orbit.

Among its payloads, the Chandra’s Atmospheric Composition Explorer-2 (CHACE-2) has been studying the Moon’s extremely thin atmosphere called the exosphere. Chandrayaan-2’s data from CHACE-2 was key to witnessing the Sun’s meteorological effect on the Moon.

What is a Coronal Mass Ejection (CME)?

A CME is a massive burst of solar plasma consisting mostly of hydrogen and helium ions blasted out from the Sun’s corona. These energetic charged particles travel through the solar system, sometimes directly striking celestial bodies like the Moon. Unlike Earth, which has a magnetic field and atmosphere to shield it, the Moon’s lack of a global magnetic field and atmosphere makes it directly vulnerable to such solar outbursts.

The Historic Observation

On May 10, 2024, a rare solar event involving a series of CMEs struck the Moon. Using CHACE-2, Chandrayaan-2 detected a dramatic rise in the total pressure and number density of neutral atoms in the Moon’s dayside exosphere — an increase by more than ten times. This observation confirmed theoretical predictions about how solar storms enhance the lunar exosphere by knocking surface atoms into the thin atmospheric layer.

Why Does This Matter?

The lunar exosphere is one of the most tenuous atmospheres in the solar system, made up of particles that rarely interact. It’s created by a combination of solar radiation, solar wind, and micrometeorite impacts that free atoms from the lunar surface. The CME impact temporarily thickens this exosphere by increasing surface sputtering — where solar ions eject atoms from the surface.

Understanding this interaction helps scientists predict how solar activity can influence the Moon’s environment, crucial for designing future lunar habitats, instruments, and astronaut safety protocols.

A Relatable Analogy for Indian Readers

Imagine the Moon’s exosphere as a fragile pond rarely disturbed, hosting delicate life underneath. Suddenly, a heavy storm (CME) hits, stirring up the whole pond and temporarily changing its nature. Just like a storm can affect crops or waterways back home, solar storms impact the Moon — and Chandrayaan-2 has been the first to witness this “storm” firsthand.

How Does This Boost India’s Space Ambitions?

• This success cements ISRO’s status as a world leader in space research through innovative technology and miniaturized instruments.

• It lays the groundwork for India’s future manned lunar missions and deeper solar system exploration.

• Encourages increased investment in space sciences and inspires the younger generation towards STEM fields.

• Strengthens international partnerships for lunar science with new, high-quality data.

Looking Forward: The Future of Lunar Exploration

With Chandrayaan-2’s orbiter still operational and set to provide more data, ISRO is aiming for Chandrayaan-3, targeting a successful lunar landing, and further missions that will carry more advanced instruments to study the Moon deeply. As several nations gear up for lunar bases and astronauts, understanding solar impacts will be fundamental. Chandrayaan-2’s observation is a crucial step in this direction.

Conclusion

India’s Chandrayaan-2 has not only expanded our horizon about the Moon’s environment but demonstrated India’s prowess in space science. By capturing the Sun’s CME impact on the Moon, this mission helped answer questions decades in the making, bringing us closer to the next frontier of exploration with confidence and knowledge.