The First Observation, Historically Scientific Achievement – Direct Impacts of Solar CME on the Moon
An achievement that Indian Space Research Organisation (ISRO) had not set out to establish has been realized using onboard scientific instruments within Chandrayaan-2 to directly witness the effects of an intense coronal mass ejection (CME) from the Sun on the Moon. This witnessing has not only been a fulfillment of scientific curiosity but also now marks a giant leap into understanding the very tenuous atmosphere of the Moon — the lunar exosphere — in providing a stout account of space weather impacts and absolute changes occurring over time on the surface.
Mission Background: Launch to Orbit
The launch was set in motion on July 22, 2019, via the GSLV-MkIII-M1 rocket from Sriharikota. Chandrayaan-2 has been loaded with 8 scientific payloads to conduct an all-round investigation of the Moon’s surface and its atmosphere, as well as the ever-changing space environment surrounding the Moon.
On August 20, 2019, it was smoothly put into lunar orbit. On September 7, 2019, Vikram lost contact with Earth due to its inability to perform soft-landing maneuvers, but the orbiter continues to function and send important scientific information back in an orbit of 100 km x 100 km.
CHACE-2 Payload: Watch on the Lunar Exosphere’s Vigilant Guard
Among the key science payloads on board the Chandrayaan-2 is the Chandra’s Atmospheric Compositional Explorer-2 (CHACE-2). The mission objective is to study the composition, distribution, and temporally varying quantities of inert particles (neutral atoms and molecules) in the lunar exosphere.
The instrument logs inaudible variations in particle density with extremely fine sensitivity to allow understanding of processes such as solar activity, micrometeoroid bombardment, or outgassing from the surface that is very much involved in lunar atmosphere.
Rare Solar Event of May 10, 2024: When CMEs Hit the Moon
A rare solar event fell on May 10, 2024, and was characterized by multiple CMEs hitting the Moon one after another. During this event, CHACE-2 recorded a very significant increase in the total pressure of the exosphere on the dayside of the Moon.
In simpler terms, the very thin gas blanket surrounding the Moon thickened — much beyond its normal state — because of the effects from CMEs and the strongly accelerated solar wind, which helped give rise to a faster designation of atoms from their surfaces.
Theory to Evidence: Increase in Density of Neutral Particles – Qualitative
Knocked down by ISRO scientists, neutral atoms and molecules generated in the exosphere had counts that jumped over an order of magnitude — from increased numbers during the event by more than an order of magnitude. The jump was at least tenfold increase.
For years, physical models had predicted this should occur during periods of intense solar activity, but direct observations were rare. CHACE-2 measurements confirmed these theoretical predictions with convincing evidence for the first time, and so made a decisive advance in lunar space weather understanding.
But Really, What is the Lunar Exosphere? A Sensitive World Without a Magnetic Shield
The Moon’s exosphere falls into surface-boundary exosphere, where gas particles are mostly confined at the surface and the chance for a collision is very rare. The Moon does not have a global magnetic field as on Earth, and so it is highly exposed to solar wind effects and CME particles.
Therefore, even a minor solar disturbance might produce short-term but measurable effects in a lunar atmosphere, such as enhanced release of sodium or potassium from the surface, or changes in pressure and density.
Impact on Future Missions: Design, Safety, and Human Settlement
Such findings have far-reaching implications.
First, it demands considering extreme space weather scenarios more adequately in the design of lander-rovers or surface instruments, such that sensors, power systems, and delicate mechanical parts are safeguarded from CME-generated particle showers and charging.
Second, if planning allows for future inhabitants or long-term bases on the Moon, then life support, radiation shielding, and air filtration will also have to be designed with respect to atmospheric dynamics and transitory dust/gas surges.
Finally, the initial step that scientists have taken is developing exosphere-like weather forecasting models that will help plan missions and organize scheduling for surface activities.
The Credence of Indian Science: Data-Backed Leverage
The reliability of data produced for uninterrupted long stretches by the Chandrayaan-2 orbiter easily attests to India’s scientific and technological prowess. This mission also puts India as a forerunner in future, especially in the area of space meteorology and study of thin atmospheric layers around planets — the challenge of lunar exploration is nothing at all.
Such an observation also contributes to the global community as the Moon seems likely to be a future setting for deep-space missions, and its environment will need to be well understood.
Research Publication: Scientific Validation of Results Amid Rigorous Checks
This study titled “Impact of a Coronal Mass Ejection on the Lunar Exosphere as Observed by CHACE-2 on the Chandrayaan-2 Orbiter”, published in Geophysical Research Letters on 16 August 2024.
This means, the results are subjected to rigorous scientific criteria, which further prove that sensitive payloads like CHACE-2 can take reliable observations of the lunar environment.
They can capture even transient, though strong, events, and future missions like this with multi-wavelength and simultaneous measurements would deliver a more comprehensive view of lunar space weather.
Conclusion: New Understanding of Lunar Weather & New Possibilities
Overall, CHACE-2 on Chandrayaan-2 has shown the drastic and rapid consequences of solar events such as CMEs on the lunar exosphere. This provides a good basis for theoretical models, refines design parameters for future lunar missions, and offers crucial information on environmental conditions in planning for sustained human presence.
A milestone in Indian space science, it distinctly tells the story of the unseen yet highly dynamic “wind” that washes over the lunar surface for the very first time.