What is a moonquake? Chandrayaan-3 detects ‘natural’ seismic activity on Moon

India’s experiments on the Moon continue, and each day Chandrayaan-3 is making discoveries in its 14-day mission. In the latest, the spacecraft’s Vikram Lander has detected “natural” seismic activity on the lunar surface. The Indian Space Research Organisation (ISRO) on Thursday said that the seismic activity-detecting equipment on the Chandrayaan-3 lander also recorded vibrations taking place due to the movements of the Pragyan rover and other payloads. In a post on X, formerly Twitter, ISRO wrote, “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 payloads. Additionally, it has recorded an event, appearing to be a natural one, on August 26, 2023. The source of this event is under investigation.” “ILSA payload is designed and realised LEOS, Bangalore. The deployment mechanism is developed by URSC, Bengaluru,” it added.

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… pic.twitter.com/Sjd5K14hPl

— ISRO (@isro) August 31, 2023

The ILSA’s main objective is to measure ground vibrations generated by natural quakes, impacts, and artificial events, reports NDTV. The vibrations of the rover’s movement on the lunar surface were recorded on 25 August. While ISRO said that the source of the ‘natural event’ is under investigation, there is increased interest in it. It indicates the possibility of a quake near the south pole of the Moon. What is a moonquake? A moonquake is the lunar equivalent of an earthquake. While they tend to be less strong than earthquakes, they last longer. While it has been long established that the moon is seismically active, the reason the lunar surface experiences quakes is different from the Earth. Moonquakes were first detected between 1969 and 1973 after Apollo astronauts placed seismometers at their landing sites around the Moon, according to NASA. [caption id=“attachment_13065302” align=“alignnone” width=“640”] This image from video provided by the Indian Space Research Organisation shows the surface of the moon ahead of the landing of the Chandrayaan-3 spacecraft. ISRO via AP[/caption] What do we know about moonquakes so far? There are four different kinds of moonquakes: 1) deep moonquakes about 700 km below the surface, probably caused by tides; 2) vibrations from the impact of meteorites; 3) thermal quakes caused by the expansion of the frigid crust when first illuminated by the morning sun after two weeks of deep-freeze lunar night; and 4) shallow moonquakes only 20 or 30 kilometres below the surface. According to NASA, the first three are mild and harmless but shallow moonquakes are unique. While earthquakes last for less than half a minute, shallow moonquakes last for a remarkably long time – more than 10 minutes. Observed moonquakes have been mostly less than 3 on the Richter scale; the largest recorded ones have a magnitude between 5 and 5.7, according to the Encyclopedia of the Solar System. The Moon “rings like a bell” owing to the absence of water and the very fractured nature of the upper few hundred meters. Unlike Earth, the Moon is dry, cool, and rigid, like a chunk of stone. So moonquakes cause vibrations like a tuning fork. However, the south pole of the Moon, where Chandrayaan-3 has landed is unexplored and ISRO’s findings are expected to provide more insight on the phenomenon. [caption id=“attachment_13065322” align=“alignnone” width=“640”] This image provided by the Indian Space Research Organisation shows a crater encountered by Chandrayaan-3- 3 as seen by the navigation camera on 27 August. ISRO[/caption] What has Chandryaan-3 discovered so far? Chandryaan-3 has made significant progress since it successfully landed on the Moon on 26 August. ISRO has been regularly sharing updates and pictures of the ongoing mission.

On Thursday, ISRO shared footage from the Moon captured by Vikram lander’s image camera of the Pragyan rover rotating in search of a safe route. “It feels as though a child is playfully frolicking in the yards of Chandamama, while the mother watches affectionately. Isn’t it?” ISRO asked in a post on X. Pragyan rover’s Laser-Induced Breakdown Spectroscope confirmed the presence of sulphur in the lunar surface near the south pole. It also detected aluminium, calcium, ferrous (iron), chromium, titanium, manganese, silicon and oxygen. The search for hydrogen is underway.

Chandrayaan-3 Mission:

In-situ scientific experiments continue .....

Laser-Induced Breakdown Spectroscope (LIBS) instrument onboard the Rover unambiguously confirms the presence of Sulphur (S) in the lunar surface near the south pole, through first-ever in-situ measurements.… pic.twitter.com/vDQmByWcSL

— ISRO (@isro) August 29, 2023

On Monday, ISRO informed that the rover came across a four-metre diameter crater just ahead of its location on the lunar surface, following which it was commanded to retrace its path. Earlier, it survived another lunar crater which was 100 mm (10 cm) deep. Last Sunday, data from the Vikram lander’s Chandra’s Surface Thermophysical Experiment (ChaSTE) payload was released, providing scientists insights into temperatures on the lunar surface. In a post, ISRO explained that ChaSTE “measures the temperature profile of the lunar topsoil around the pole, to understand the thermal behaviour of the Moon’s surface”. ISRO chairman S Somanath said that the mission would be completed. “Everything is working fine, and we are hopeful that by the end of 14 days, our mission will be successfully completed,” he told news agency PTI on Thursday.

VIDEO | "Everything is working fine, and we are hopeful that by the end of 14 days, our mission will be successfully completed," says ISRO chairman S Somanath on Chandrayaan-3.#Chandrayaan3Success pic.twitter.com/zAsGzHI9TQ

— Press Trust of India (@PTI_News) August 31, 2023

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The Moon mission will last for 14 days which is equivalent to one lunar day. After that, it will be night on the Moon. During this period, the lander and rover, which are powered by solar energy, will slow down. With inputs from agencies