Chandrayaan-3 is expected to land on the lunar south pole on August 23, 2023, at around 6:04 pm IST. If Chandrayaan-3 successfully lands on the Moon's south pole, India will become the first country to softly land a spacecraft on the lunar south pole, and the fourth country to achieve a soft landing on the Moon, after the United States, the Soviet Union, and China. Most lunar missions attempt landings on the lunar south pole because the region is a treasure trove of scientific secrets and cosmic mysteries.
These planned Moon missions include NASA's Artemis III, and the Lunar Polar Exploration mission (LUPEX) or Chandrayaan-4. Roscosmos's Luna 25 planned to land on the Moon's south pole on August 21, 2023, but it crashed on the lunar surface on August 20, 2023, due to an uncontrolled manoeuvre. NASA's Artemis III aims to make history by landing the first humans on the lunar south pole. LUPEX is a joint robotic exploration mission between the Japanese Aerospace Exploration Agency (JAXA) and the Indian Space Research Organisation (ISRO), and aims to obtain information on the quantity and forms of water resources present on the Moon, in order to determine the feasibility of utilising these water resources for future sustainable space exploration missions. LUPEX aims to explore the lunar south pole.
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Why ISRO is attempting a soft landing on the lunar south pole for Chandrayaan-3
Chandrayaan-3's primary objective is to put a lander and a rover on the Moon's highlands near its south pole, and to demonstrate end-to-end landing and roving capabilities. Apart from demonstrating safe and soft landing and roving capabilities on the lunar surface, Chandrayaan-3's objectives are to conduct in-situ scientific experiments, and develop and demonstrate new technologies required for interplanetary missions.
Space agencies aim to land their spacecraft on the lunar south pole due to scientific motivations.
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"Most lunar missions target the Moon's south pole as the landing site because the lunar poles harbour an environment that represents the remarkable diversity on Earth, and are strikingly distinct from the familiar middle latitudes," Manish Purohit, a former ISRO scientist, who was involved in the Mangalyaan and Chandrayaan-2 missions, told ABP Live.
Since the lunar south pole is similar to Earth’s diversity, exploring it will allow scientists to obtain insights into how the Earth was billions of years ago, and if it will be possible to colonise the Moon in the future.
It is believed that water-ice reserves are buried beneath the lunar surface, especially below the poles, which is another reason space agencies are keen to explore the polar regions. Chandrayaan-1's Moon Impact Probe hinted at the presence of water molecules below the Moon's crust. Therefore, space research organisations intended to delve deeper into this discovery by sending spacecraft to the lunar poles, and conducting experiments on the lunar surface.
“Central to this exploration quest is the possibility of water-ice reserves being concealed beneath the lunar surface. Building upon the insights garnered from Chandrayaan-1's Moon Impact Probe, which hinted at the presence of water molecules beneath the Moon's crust, space research organisations worldwide are poised to substantiate this revelation with conclusive experiments directly on the lunar terrain,” Dr Purohit said.
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The lunar poles are quite dark, have unique topography and geology, and harbour conditions favourable for the preservation of water molecules in the form of ice. Several remote observations have been performed, most of which have hinted at the possibility of water-ice reserves being preserved beneath the Moon’s surface.
“The lunar poles, shrouded in perpetual darkness, offer an intriguing locale for this ambitious endeavour. The unique topography and geology of these regions create conditions conducive to the preservation of water molecules in the form of ice. Remote observations have consistently pointed to the potential existence of water-ice reserves beneath the moon's surface, awaiting scientific confirmation and deeper exploration,” Purohit explained.
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Chandrayaan-3’s experiments on the lunar south pole can be useful for future crewed missions
Not only will a successful landing of Chandrayaan-3 on the lunar south pole mark a historic moment for India, but will also allow the spacecraft to perform experiments on the ice and explore how these reserves could be used to extract water, oxygen and fuel for future crewed missions to the Moon.
Chandrayaan-3 has chosen the south pole of the moon as its landing site because the south pole of the lunar surface holds significant quantities of ice that could be used to extract water, oxygen, and fuel for future crewed missions to the Moon. Chandrayaan-3 will conduct experiments for two weeks,” Debadatta Mishra, a former ISRO scientist, and co-founder of Erisha Space, a New Delhi-based space-tech firm, told ABP Live.
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Experiments to be performed by Chandrayaan-3 payloads
Chandrayaan-3’s lander module, which consists of a lander, called Vikram, and a rover, called Pragyan, will attempt a soft landing on the lunar south pole on August 23.
The lander's payloads are Chandra's Surface Thermophysical Experiment (ChaSTE), Instrument for Lunar Seismic Activity (ILSA), Laser Retroreflector Array (LRA) Rover, and Radio Anatomy of Moon Bound Hypersensitive ionosphere and Atmosphere (RAMBHA).
ChasTE will carry out measurements of thermal properties such as thermal conductivity and temperature of elements on the lunar surface near the south pole; ILSA will measure the seismicity around the landing site and describe the structure of the lunar crust and mantle; and RAMBHA will study the gas and plasma environment.
The lander module has a mass of 1,752 kilograms, and a mission life of one lunar day, which is equivalent to 14 Earth days. It has a power generation capacity of 738 Watts.
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The rover is equipped with two payloads, which are the Alpha Particle X-ray Spectrometer (APXS), and Laser Induced Breakdown Spectroscope (LIBS).
APXS will help determine the elemental composition of the lunar soil and rocks around the landing site. The elements to be studied include magnesium, aluminium, silicon, potassium, calcium, titanium and iron.
LIBS will conduct qualitative and quantitative elemental analysis in order to infer the chemical and mineralogical composition of the lunar surface.
The rover has a mass of 26 kilograms, a mission life of one lunar day, and a power generation capacity of 50 Watts.
The lander will touch down on the lunar surface with a horizontal velocity of less than 0.5 metre per second, a vertical velocity of less than two metres per second, and a slope less than 120 degrees.
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