Context: Recently, Imaging Infrared Spectrometer (IIRS) instrument onboard the Chandrayaan-2 lunar orbiter has confirmed the presence of both hydroxyl ions (OH) and water molecules (H2O) on the surface of the moon.

• However, Discovery of hydration on lunar surface was originally made by Chandrayaan-1, but low resolution of its mapper could not quantify between readings from OH & water molecules.

About Chandrayaan-2 mission

• Chandrayaan-2 is an Indian lunar mission to explore the unchartered south pole of the celestial body by landing a rover.
• Mission coverage: This is a unique mission that aims at studying not just one area of the Moon but all the areas combining the exosphere, the surface as well as the sub-surface of the moon in a single mission.
• The mission aims for enhancing our understanding of the Moon, stimulate the advancement of technology, promote global alliances and inspire a future generation of explorers and scientists.

Why South Pole?

• The Lunar South pole is especially interesting because of the lunar surface area that remains in shadow is much larger than that at the North Pole.
• There could be a possibility of presence of water in permanently shadowed areas around it.
• In addition, South Pole region has craters that are cold traps and contain a fossil record of the early Solar System.
• Launching: The GSLV Mk-III is India's most powerful launcher to date, and has been completely designed and fabricated from within the country.

Components

This highly complex mission brought together an Orbiter, Lander and Rover with the goal of exploring South Pole of the Moon.

• Orbiter: The Orbiter will observe the lunar surface and relay communication between Earth and Chandrayaan 2's Lander — Vikram.
• Vikram Lander: The lander was designed to execute India's first soft landing on the lunar surface.
• Pragyan Rover:The rover was a 6-wheeled, AI-powered vehicle named Pragyan, which translates to 'wisdom' in Sanskrit.

Key Findings

• The new infrared spectrometer IIRS was designed to operate in the 0.8 to 5 μm range and mapped the lunar surface from a circular orbit of 100km from the Moon’s surface.
• It has quantified the amount of water molecules present on the lunar surface regionsand distinguished parts of the moon which are water-rich and scant in hydration.
• Earlier detection: Water was originally discovered by the Chandrayaan-1 mission, in 2008, but the low resolution of its mapper could not quantify between the OH and water molecules readings.
• Two instruments-M3 instrumentand MIP instrument on CHACE instrument, confirmed the presence of water.
• Location of water: The data confirmed that hydration exists on sunlit portions, permanently shadowed craters, and Polar region.
• The silicate rocks called plagioclase absorbed more water, while older highland rocks that rise above the surface showed weak signatures of hydration.

Proposed Theories regarding presence of water on Moon

• The authors propose a number of theories for the source of hydration on the moon, including
• Origins from within the Moon’s internal mantle processes of the past
• Water or ice-bearing comets could have crashed into the Moon millions of years ago, depositing water molecules
• Space weathering

About Space Weathering

• It is the interaction of the solar wind or charged solar particles with the surface of the Moon, in the absence of a protective atmosphere or magnetic field.
• This process is similar to weathering processes on Earth, there are weathering effects on atmosphere-less bodies exposed to the vacuum of space.
• Space weathering can occur not just from the solar wind but also from meteors and meteorites, comets, cosmic rays, and more.
• It can also alter reflection and spectral readings and the optical properties of surfaces, sometimes resulting in incorrectly interpreted data.
• This could be the most likely and widespread source of water.
• By the process of space weathering, the lunar regolith that is rich in silicates and oxides are bombarded at high speeds of up to 800 mps by charged particles like protons and electrons from the sun. This causes chemical and structural changes in the composition of the soil at impact, trapping a proton from the solar wind and causing hydrogen to bond with oxygen to eventually form water.