A Gamma-ray spectrometer (GRS) for Chang’e 2, developed by Purple Mountain Observatory (PMO) of Chinese Academy of Sciences, started work at 19:41 on 4 October 2010. It is now in good operation with data received.

　 As one of the seven main payloads of Chang’e 2, the GRS is designed to detect lunar substances. It can acquire data concerning the content and distribution of chemical elements on lunar surface via detecting gamma-ray spectrum “fingerprint” of the elements impinged by cosmic rays.

　 Compared to the previous GRS for Chang’e 1, the GRS of the second generation, equipped with a new scintillation detector, can fulfill its task with more accuracy due to its higher energy resolution and sensitivity. It can therefore further find the resource-rich regions on lunar surface, identify new types of rocks, and provide scientific data for research on the composition, geological history, and thermal history of the Moon.

　 PMO initiated GRS research in 2001 and developed the first GRS in 2006, which was launched into space along with Chang’e 1 on 24 October 2007 and which successfully carried out its mission.