The Chandra’s Atmospheric Composition Explorer-2 (CHACE-2), a quadrupole mass spectrometer onboard Chandrayaan-2 mission has made the first-of-its-kind observations of the global distribution of Argon-40 in the tenuous lunar exosphere.  These observations provide insight on the dynamics of the lunar exospheric species, as well as on the radiogenic activities in the first few tens of meters below the lunar surface.