Distribution of Sodium on the Moon’s surface


  • Scientists from Indian Space Research Organisation (ISRO) have mapped out the global distribution of sodium on the Moon’s surface.
  • They used the CLASS instrument (Chandrayaan-2 large area soft X-ray spectrometer) carried by the second Indian Moon mission, Chandrayaan-2.

How was it done?

  • This is the first effort to provide a global-scale measurement of sodium on the lunar surface using X-ray fluorescent spectra.
  • Non-destructively analysing the composition of materials is a popular application for X-ray fluorescence.
  • When the sun emits solar flares, the moon is exposed to a significant amount of X-ray radiation, which causes X-ray fluorescence.
  • The CLASS counts the total amount of X-ray photons arriving from the moon and assesses their energy.
  • The intensity is a measurement of how many atoms are present, and the energy of the photons reveals the number of atoms (for example, sodium atoms release X-ray photons of 1.04 keV).

Other Findings:

  • Rock samples were returned from earlier lunar trips like Apollo-11, Luna, and Chang’e-5.
  • The sodium content of the rocks was properly measured in those missions.
  • Apart from the trace amounts detected in lunar rocks, a recent analysis by the Chandrayaan group reveals that there is a thin veneer of sodium atoms that are weakly linked to the lunar surface (as mentioned earlier).
  • When enough energy is provided to them by solar UV light and solar wind ions, these sodium atoms on the surface are released.

Way Forward:

  • This achievement by Indian Space Research Organization (ISRO), is a great step towards scientific exploration of lunar surfaces.
  • The scientists of Indian Space Research Organization (ISRO) have stated that “As the solar cycle is in its ascending phase, we expect more solar flares that would ensure a larger coverage of all elements on the moon by CLASS at the highest spatial resolution ever”.


Source The Hindu