Building a mosaic of Mars
To mark 20 years of ESA’s Mars Express, the High Resolution Stereo Camera (HRSC) team has produced a new global colour mosaic of Mars by combining 90 high-altitude HRSC images.
This image shows an example of the kind of high-altitude HRSC image used to create the global mosaic, taken during HRSC orbit 21 688. The grey terrain comprises data from NASA’s Mars Orbiter Laser Altimeter, while the HRSC data forms the two coloured slices. Martian coordinates are displayed around the discs for geographical context.
Left: A red-green-blue-composite showing how the surface looks in visible light. Note the light blue colour of the northern and southern limbs, caused by the camera having a shallower view through the martian atmosphere (which therefore had a stronger influence on the images). Such regions were excluded from the global mosaic.
Right: An infrared-red-green-composite. Such unusual views (those including the infrared channel) offer a possible way to examine Mars’ surface reflectivity in various wavelengths, and have also been inspected to detect artefacts or holes in the data comprising the global mosaic.
