India’s Chandrayaan 3 lander may have detected its first moonquake

India’s Chandrayaan 3 only recently made its historic lunar landing, but it is already collecting intriguing new data about the moon. Just a few days after its landing, one of its instruments detected what could be a moonquake, the first detection of such an event in almost 50 years.

The detection was made using Chandrayaan 3’s Instrument for Lunar Seismic Activity, or ILSA, which measures vibrations around the craft’s landing site. On August 26, it detected an event lasting a few seconds, which appears to be due to natural process — that is, it was caused by changes to the moon’s interior and not due to activities of the lander. The The Indian Space Research Organization (ISRO), shared two graphs showing detections of vibrations caused by the rover moving around on August 25, on the left, and the apparently natural event on August 26, on the right.

Chandrayaan-3 Mission:
In-situ Scientific Experiments

Instrument for the Lunar Seismic Activity (ILSA) payload on Chandrayaan 3 Lander
— the first Micro Electro Mechanical Systems (MEMS) technology-based instrument on the moon —
has recorded the movements of Rover and other…

— ISRO (@isro) August 31, 2023

The agency warns that more research is needed to know whether the August 26 event was definitely a moonquake. But if so, it could help scientists gain valuable understanding about the structure and interior of the moon.

The Indian Space Research Organization's lunar lander for the Chanrayaan-3 mission.
The Indian Space Research Organization’s lunar lander for the Chanrayaan-3 mission. Indian Space Research Organization (ISRO) / Indian Space Research Organization (ISRO)

The ILSA instrument, which is one of three instruments on board the lander, is designed specifically to look for seismic events on the moon. “ILSA comprises a cluster of six high-sensitivity accelerometers, which are indigenously fabricated using the silicon micromachining process,” the ISRO explains. “The core-sensing element consists of a spring-mass system with comb-structured electrodes. External vibrations lead to a deflection of the spring, resulting in a change in capacitance, which is converted into voltage.”

This allows the instrument to measure vibrations on the moon’s surface, which could come from natural events or from the movements of other elements of the mission such as the rover. The rover, named Pragyan, was carried on board the lander and has been deployed to explore the region of the moon’s south pole around the landing site.

The rover carries its own instruments, comprising two spectrometers, which will be used to look at the chemical composition of the lunar surface. The moon’s south pole is an especially important location as it is thought to host water ice in some of its craters, which could be an important resource for future crewed missions there.

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