Coordinated Analysis of Orbital and Ground Remote Sensing Data along the Opportunity Rover Traverse from Endurance to Erebus Crater

Introduction: Observations made by the Opportunity rover during its traverse south from Eagle crater show that the hematite bearing plains are an aeolian lag deposit consisting of hematite spherules and basal-tic sand, along with a nanophase iron oxide bearing dust component, that has been worked into ripples [1,2,3]. The hematite spherules, which have weathered out of the sulfate rich outcrop material that underlies the lag deposit, are concentrated at the surface [1,2,3,4,5]. It is this hematite bearing lag deposit that dominates the orbital signature in the vicinity of the landing site. However, the orbital signature changes gradually along Opportunity's traverse to the south. The albedo of the plains material as seen in a MOC narrow angle image (figs. 1 and 2) increases along the traverse south before the mottled terrain is encountered. The thermal inertia of the higher albedo plains area decreases relative to the lower albedo plains (fig. 3) and the red to blue ratio as detected by the Mars Express OMEGA spectrometer increases to the south [6]. Systematic pancam foreground observations collected by the rover with a consistent viewing geometry also show an increase in the red to blue ratio as Opportunity traversed south. This change in the nature of the lag deposit from the lower albedo plains to the higher albedo plains is consistent with the incorporation of an increased amount of nanophase ferric iron oxide bearing dust derived locally from outcrop material. Opportunity Traverse: Although orbital remote sensing data (fig. 1) covers the traverse from Endurance to Erebus crater, Pancam analysis was focused on the portion of the traverse between the heat shield (sol 358), situated in the lower albedo plains, and purgatory dune (sol 447), which is located in the higher albedo plains (fig. 1). The mottled terrain to the south, in which areas of underlying etched terrain materials are exposed and is visible in the vicinity of Erebus (fig. 1) also corresponds to an area of higher thermal inertia (fig. 3). Several OMEGA pixels also cover Opportu-nity's traverse [6]. For the portion of the traverse between the heat shield and purgatory dune, the route toward Erebus crater was punctuated by stopping at crater waypoints. However, large legs of the traverse occurred in between the craters. Along the traverse, systematic foreground observations were often acquired by the pancam to image the plains material Pancam Foreground Observations: The systematic pancam foreground observations document the plains material …