Chandrayaan-3 detects 250+ seismic signals of moonquakes from lunar south pole

The study highlighted that the longest continuous seismic record from ILSA lasted 14 minutes

Chandrayaan-3 has made a historic first by detecting over 250 seismic signals from the Moon’s south pole, including 50 unique signals that could potentially be linked to moonquakes, an equivalent of earthquake on the lunar soil. This marks the first seismic data collection from this part of the lunar surface and the first since the Apollo missions.

The Instrument for Lunar Seismic Activity (ILSA), mounted on the Vikram lander, conducted this pioneering experiment at coordinates of 69.37 degree south and 32.32 degree east, the Times of India reported. Operating from August 24 to September 4, 2023, the ILSA is the first lunar instrument to capture ground accelerations in this region, utilising sensors manufactured with cutting-edge silicon micromachining technology.

Also Read | ISRO releases Chandrayaan-3 data to global scientific community; check key details of the mission

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

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

Also Read | Chandrayaan-3 landing anniversary on August 23: ISRO to unveil images from Vikram Lander and Pragyan Rover

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

The researchers identified about 50 instances where the seismic signal amplitude significantly deviated from the expected background levels. These anomalies, which include peaks reaching up to 700 μg (microgram), are considered ‘uncorrelated events’ as they occurred when no rover activities were reported.

Also Read | ISRO’s Chandrayaan-3 data confirms Moon's surface was once covered in an ocean of magma

While the mission’s primary focus was not on detecting deep or shallow quakes, the data suggests these signals could be indicative of 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.