Principal Component Analysis of Geochemical Data at Gusev Crater

Introduction: Since January 2004, the twin rovers Spirit and Opportunity of the Mars Exploration Rover (MER) mission have been able to investigate their respective landing sites thanks to the Athena Science Payload [1]. This scientific payload includes the Alpha Particle X-ray Spectrometer (APXS) instrument [2], whose role is to determine the elemental composition of martian soils and rocks. Due to a largely increased mobility compared to the Mars Pathfinder mission and thanks to their amazing longevity, Spirit and Opportunity have been able to drive several kilometres away from their landing site locations. Given the large number of APXS measurements (Table 1) multidimensional analysis [3] appears to be an adequate and original tool to investigate such a variety of samples. Thus, our Principal Component Analysis (PCA) performed on rock measurements at Gusev gives pertinent results, in particular concerning the diversity observed among the rocks of the Columbia Hills encountered by Spirit.