A global colour mosaic of Mars from Mars Express HRSC high altitude observations

TL;DR

This paper presents a novel method to create a continuous, high-resolution global colour mosaic of Mars by minimizing atmospheric scattering effects, enabling detailed surface analysis over large distances.

Contribution

A new iterative approach for constructing a self-consistent, high-altitude colour mosaic of Mars that preserves long-range colour variations and reduces atmospheric scattering influence.

Findings

Produced a global colour mosaic with detailed surface features.

Enabled continuity of colour information over large distances.

Improved the utility of HRSC images for geological analysis.

Abstract

The ever-changing transparency of the Martian atmosphere hinders the determination of absolute surface colour from spacecraft images. While individual high-resolution images from low orbit reveal numerous colour details of the geology, the colour variation between images caused by scattering off atmospheric dust can easily be of greater magnitude. The construction of contiguous large-scale mosaics has thus required a strategy to suppress the influence of scattering, often a form of high-pass filtering, which limits their ability to convey colour variation information over distances greater than the dimensions of single images. Here we use a dedicated high altitude observation campaign with the Mars Express High Resolution Stereo Camera (HRSC) (Neukum and Jaumann, 2004; Jaumann et al., 2007), applying a novel iterative method to construct a globally self-consistent colour model. We apply the model to colour-reference a high-altitude mosaic incor-porating long-range colour variation information. Using only the relative colour information internal to individual images, the influence of absolute image to image colour changes caused by scattering is minimised, while the model enables col-our variations across image boundaries to be self-consistently reconstructed. The resulting mosaic shows a level of colour detail comparable to single images, while maintaining continuity of colour features over much greater distances, thereby increasing the utility of HRSC colour images in the tracing and analysis of martian surface structures.