August 23rd, 2023 is the day when India made history by becoming the first nation to land a mission (robotic spacecraft Chandrayaan-3) near the moon’s South Pole. Exactly a year later, on August 23rd 2024, as India celebrates National Space Day, the Indian Space agency ISRO will reveal the findings and scientific discoveries made by the country’s third lunar mission, WION has learnt.
So far, ISRO has only revealed some initial inferences about the mission. The significant findings are to be revealed on Friday, at the Bharat Mandapam in New Delhi, as the Indian Government’s Department of Space conducts a massive event on the day. This will be presided over by the Indian Head of State, President Droupadi Murmu.
Chandrayaan-3’s preliminary findings and feats:
Temperature variations on lunar soil
During its 10-day lifetime on the Lunar surface, the scientific probes and sensors aboard Chandrayaan-3’s Vikram Lander and Praygan rover conducted multiple in situ experiments.
One of the significant preliminary findings was about the drastic temperature variation in the Lunar soil near the south polar region. “On the Lunar top soil (surface), the temperature is 50 degrees Centigrade, and barely 10 cm below the surface, the temperature is minus 10 degrees Centigrade, ISRO had revealed in August 2023.
For context, In India, if you are in the deserts of Rajasthan (north-west) during peak summer, the temperature could well be around 50 degrees Centigrade. Likewise, if you are in Jammu and Kashmir (north) during winters, the temperature could well be minus 10 degrees centigrade or even colder. Kashmir and Rajasthan are well over 600km apart, and have different altitudes, terrain, and climatic conditions. On the Lunar surface, all it takes is 10cm of digging beneath the top soil to see such temperature differences.
This study was performed by the ChaSTE (Chandra’s Surface Thermophysical Experiment) probe. Notably, this study is done during the Lunar day, when sunlight is available at the landing site. Lunar nighttime temperatures could be much colder.
According to NASA, lunar daytime temperatures near the equator reach 120 degrees centigrade, while nighttime temperatures get to minus 130 degrees centigrade. The Moon’s poles are even colder.
NASA’s equipment even found a place in the floor of the Moon’s Hermite Crater that was detected to be minus 250 degrees Centigrade, making it the coldest temperature measured anywhere in the solar system.
Did ISRO’s ILSA detect a ‘moon quake’?
Further, ISRO’s Instrument for Lunar Seismic Activity (ILSA) payload on the Chandrayaan-3 Vikram Lander is the first instance of a Micro Electro Mechanical Systems (MEMS) technology-based instrument on the moon. It has recorded the vibrations occurring due to the movements of Rover and other payloads. According to ISRO, this instrument had also recorded what is suspected to be a ‘moon quake’.
ISRO unravels elemental composition of Lunar soil
The Laser-Induced Breakdown Spectroscopy (LIBS) instrument onboard the Chandrayaan-3 Pragyan rover had made the first-ever in situ measurements of the elemental composition of the lunar surface near the South Pole. These in situ measurements unambiguously confirmed the presence of sulphur in the region, ISRO said.
LIBS is a scientific technique that analyses the composition of materials by exposing them to intense laser pulses. A high-energy laser pulse is focused onto the surface of a material, such as rock or soil. The laser pulse generates an extremely hot plasma. The collected plasma light is analysed by sensors, and the elemental composition of the material is determined.
ISRO’s preliminary analyses had unveiled the presence of Aluminium (Al), Sulphur (S), Calcium (Ca), Iron (Fe), Chromium (Cr), and Titanium (Ti) on the lunar surface. Further measurements have revealed the presence of manganese (Mn), silicon (Si), and oxygen (O). Thorough investigation regarding the presence of hydrogen is underway, ISRO had said in August 2023.
When Vikram lander hopped on the Moon
Chandrayaan-3 landed vertically like a helicopter. In the words of ISRO, VSSC Director Dr. S. Unnikrishnan Nair, “It was a feather-like soft-landing”.
Let’s imagine that the Chandrayaan-3 lander wants to take off again and come back. In that case, it would have to fire its engines and almost launch itself like a rocket and reach Lunar orbit.
As a minor step or hop towards that ambitious future goal, the Vikram lander of Chandrayaan-3 was commanded to perform a hop test, which it successfully performed.
Think of the hop as an exercise move – jumping up from a point and landing a few centimetres beside where you started from. By performing this manoeuvre, ISRO has re-fired the engines of the Vikram lander and gathered valuable data on engine firings on the Lunar surface.
“On command, it (Vikram Lander) fired the engines, elevated itself by about 40 cm as expected and landed safely at a distance of 30 – 40 cm away. Importance?: This ‘kick-start’ enthuses future sample return and human missions!” ISRO has said in a Twitter post, back in 2023.
On the moon, the gravity is barely 1/6th that of Earth. The Lunar terrain is uneven and strewn around with fine Lunar dust, which gets kicked up when an engine is fired on/near the surface and this fine dust (which remains suspended over the site for a few hours) can cause issues for the craft’s on-board sensors, cameras, and instruments.
Given the uneven terrain, the craft must be able to take off, hover and land smoothly and not get toppled over. By executing all this successfully, ISRO has proven the robustness and reliability of their technology.