NASA's mission to Mars 100000 MSL APXS Caltarget,Sep 10,2012 Mg Alpha Particle X-Ray Na Fe Spectrometer (APXS 10000 Ca K Zr 1000 Ar 100 0 100200300 400500600700800900 1000 channel3 Alpha Particle X-Ray Spectrometer (APXS)