Chandrayaan-3 has made a groundbreaking discovery by detecting more than 250 seismic signals from the Moon’s south pole, including 50 distinct signals potentially linked to moonquakes—lunar equivalents of earthquakes. This marks the first seismic data collection from this region of the lunar surface and represents the first such data since the Apollo missions.

The Instrument for Lunar Seismic Activity (ILSA), mounted on the Vikram lander, conducted this pioneering experiment at coordinates 69.37 degrees south and 32.32 degrees east, according to the Times of India. Operating from August 24 to September 4, 2023, ILSA utilized advanced silicon micromachining technology to capture ground accelerations in this area, making it the first lunar instrument to do so.

The significant findings were detailed in a recent paper published in ICARUS, a prestigious journal dedicated to planetary science. Authored by researchers from ISRO's Laboratory for Electro-Optics Systems (LEOS) in Bengaluru, the study reveals that approximately 200 of the recorded signals are associated with the activities of the rover Pragyan and other scientific operations, while around 50 signals remain unexplained.

LEOS Director Sriram commented on the findings: “Out of the 250 seismic events detected, about 200 correlate with Pragyan’s movements or other instrument operations. The remaining 50 signals do not align with any known activities, suggesting they warrant further investigation to determine their origins.”

The study noted that the longest continuous seismic record from ILSA lasted 14 minutes, with significant amplitude variations corresponding to Pragyan’s movement. As the rover traversed the lunar surface at about 1 cm per second, the impact of its wheels generated complex vibration signals detected by ILSA.

Researchers identified around 50 instances where seismic signal amplitudes significantly deviated from expected background levels. These anomalies, with peaks reaching up to 700 μg (micrograms), are considered 'uncorrelated events' since they occurred during periods when no rover activities were reported.

While the mission’s primary goal was not to detect deep or shallow quakes, the data suggests that these signals may indicate previously unknown lunar seismic activity. The paper notes that the frequency content of these signals ranges up to 50 Hz, with some lasting only a few seconds.