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Updated: Nov 01, 2019 10:30 IST

One of the eight payloads aboard Chandrayaan 2 orbiter, the Chandra’s Atmospheric Composition Explorer-2 (CHACE-2), has sent back data on the variations in the concentration of Argon in the thin gaseous atmosphere around the moon called lunar exosphere.

Argon-40, which is one of the isotopes of the noble gas, is an important constituent of this exosphere. It originates from the radioactive disintegration of Potassium-40.

The radioactive potassium 40 that is present deep below the lunar surface disintegrates to 40Ar, which, in turn, diffuses through seepages and faults and makes its way up to the lunar exosphere.

Chace-2, which is a neutral mass spectrometer, has detected day-night variations of the concentration of Argon-40. The element being a condensable gas at the temperatures and pressures that prevail on the lunar surface condenses during the lunar night. After lunar dawn, it starts getting released to the lunar exosphere again increasing the concentrations.

“What this shows is that another payload aboard the orbiter, which is to work for nearly seven years, is working properly. This is a welcome sign as it means that we will get valuable data from the mission. However, no scientific conclusion can be made from the observations over a single day. Several readings would be needed for statistical analysis and once the analysis happens the findings would be released after publication in peer-reviewed journals,” said Ajay Lele, Senior Fellow working with space security and strategic technologies at the Institute for Defence Studies and Analyses.

In 2008, a paper was co-written by scientists from ISRO and NASA to reveal Chandrayaan 2 detecting presence of water and hydroxyl molecules.