Chandrayaan-2 finds sodium on the moon

The X-ray spectrometer ‘CLASS’ on the Chandrayaan-2 Orbiter has mapped an abundance of sodium on the moon for the first time, according to the Indian Space Research Organisation (ISRO).

Chandrayaan-1 X-ray Fluorescence Spectrometer (C1XS) detected sodium from its characteristic line in X-rays which opened up the possibility of mapping the amount of sodium on the Moon.
These sodium atoms on the surface are liberated when enough energy is given to them by solar ultraviolet radiation and solar wind ions.

X-ray fluorescence is commonly used to study the composition of materials in a non-destructive manner.
When the sun gives out solar flares, a large amount of X-ray radiation falls on the moon, triggering X-ray fluorescence.
The CLASS measures the energy of the X-ray photons coming from the moon and counts the total number. The energy of the photons indicates the atom (for instance, sodium atoms emit X-ray photons of 1.04 keV) and the intensity is a measure of how many atoms are present.

Sodium is the only element apart from potassium that can be observed through telescopes in the lunar atmosphere (its exosphere). This new map of sodium would enable understanding of the surface-exosphere connection.
When compared to Earth, the moon is significantly depleted of volatile elements such as sodium. The amount of volatiles on the moon today can be used to test formation scenarios of the Earth-Moon system.
Sodium can be used as a tracer of the volatile history of the moon
The new findings from Chandrayaan-2, provide an avenue to study surface-exosphere interaction on the moon, which would aid development of similar models for mercury and other airless bodies in our solar system and beyond

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