Chinese rover obtains first spectrum of lunar rock

The Active Particle-induced X-ray Spectrometer (APXS) that was carried by Chang'e-3 satellite's Yutu rover, obtained its first X-ray fluorescence spectrum of lunar regolith around the landing site on December 25.

An initial analysis indicates that eight major rock-forming elements (Mg, Al, Si, K, Ca, Ti, Cr and Fe) and at least 3 minor elements (Sr, Y and Zr) of the Moon can be identified in this spectrum.

APXS was firstly powered on December 23, and an in-flight calibration of a standard basalt rock sample mounted on the rover was accomplished in five minutes, which proved its stable performance on the Moon.

Two days later, APXS was successfully deployed to about two to three centimeters above the lunar regolith surface by the robotic arm of Yutu and started the detection mode.

APXS was not only an X-ray spectrometer, but also served as a distance sensor during the deployment by making use of how X-ray count rate varied with distance.