The first hiking maps of Mars
Mon Feb 12, 2007 at 14:29 UTC
Scientists using data from the HRSC experiment onboard ESA's Mars Express spacecraft have produced the first 'hiker's maps' of Mars. Giving detailed height contours and names of geological features in the Iani Chaos region, the maps could become a standard reference for future Martian research.
The maps are known as topographic maps because they use contour lines to show the heights of the landscape. The contour lines are superimposed upon high-resolution images of Mars, taken by the High-Resolution Stereo Camera (HRSC) onboard Mars Express. On Earth, such maps are used by hikers and planning authorities.
They are known in the UK as ordinance survey maps. Every country has its own equivalent. The contour lines themselves were determined using data from the HRSC.
This data has been transformed into three-dimensional computer models of Mars, known as the HRSC Digital Terrain Models (DTMs).
The new maps have been produced under the leadership of the Principal Investigator (PI) G. Neukum (Freie Universität Berlin), as part of the effort of the science and experiment team of the HRSC experiment, by J. Albertz and S. Gehrke of the Institute for Geodesy and Geoinformation Science, Technische Universität Berlin, in cooperation with the German Aerospace Centre (DLR), Institute of Planetary Research, Berlin.
They used the HRSC DTMs of the Iani Chaos region to produce a series of topographic maps at different scales, from 1:200 000 down to 1:50 000.
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: ESA / DLR / FU Berlin (G. Neukum)
High resolution image (2.2 MB)
A topographic map sheet of a part of the Iani Chaos region on Mars, based on image data obtained with the High Resolution Stereo Camera (HRSC) on board ESA's Mars Express. Such 'Topographic Image Map Mars 1:200 000' has been designed as an example of a possible standard map series for the HRSC experiment.
So far all map sheets are based on HRSC orthoimage mosaics and show contour lines derived from HRSC Digital Terrain Models (DTMs). Furthermore, they feature Martian topographic names (craters, mountains, valleys, etc.), cartographic grids, sheet names, individual designations, and all respective legend entries.
Should the outlined map series be realized, the planet Mars would be covered by 10 372 particular map sheets in equal-area map projections – 10 324 of them within the ±85° latitude zone in Sinusoidal Projection, supplemented by 48 polar sheets in Lambert Azimuthal Equal-area Projection. While each of the quadrangles spans 2° in latitude, longitudinal extents increase from 2° near the equator up to 360° toward the poles in order to keep the mapped area approximately constant. Therefore, the general layout of all maps appears very similar; each sheet features an overall width of 830 millimetres and a height of 700 millimetres.
The sheets of such a 'Topographic Image Map Mars 1:200 000' standard series as outlined here can be subdivided into sheets of quarters and sixteenths for systematic cartography in larger scale, 1:100 000 and 1:50 000 respectively. Within their mapped surfaces, the sheets differ in image resolution due to their different scales.
Although few effects of image compression are recognizable in the largest scale (such as the 1:50 000 map at, for instance, shadowed slopes), in general more texture details of the Martian surface become visible. A contour line equidistance of 250 metres is common for most of the sheets of the 1:200 000 topographic maps. In larger scales, a more subtle representation of the terrain topography is achieved by denser contour lines.
All map sheets have been generated using the cartographic software system 'Planetary Image Mapper' (PIMap), which has been developed at Technische Universität Berlin for cartographic presentation of HRSC data. Topographic map contents, graticules, frame lines, map titles as well as typical marginal elements can be generated and/or combined to the digital map sheet with PIMap.
The data were obtained on 5, 8 and 11 October 2004 (during orbits 0912, 0923 and 0934 of Mars Express) with best possible ground resolutions.
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: MOLA Science Team
High resolution image (3.8 MB)
Iani Chaos is a large depression with dimensions of 330 kilometres in length and 430 kilometres in width, located at 2.8° south and 342.5° east. Individual blocks of rock and hills form a disrupted, knobby pattern in an apparently 'chaotic' distribution. Terraces and 'islands' are likely remnants of the pre-existing surface, which collapsed after cavities had formed beneath it - ice in these cavities might have been melted by volcanic heat and flowed into Ares Vallis towards the northern lowlands. Due to the hints of water having formed it, such a landscape is of special geological interest but it is also well suited to present the design and the potential of the topographic map series.
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: ESA / DLR / FU Berlin (G. Neukum)
High resolution image
This image of Mars taken by the High Resolution Stereo Camera on board ESA's Mars Express outlines the scales (1:200 000, 1:100 000 and 1:50 000) of the series of topographic maps of the planet's surface that can be realized thanks to HRSC data.
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: ESA / DLR / FU Berlin (G. Neukum)
High resolution image (2.4 MB)
A topographic map of an adjacent area of the Iani Chaos region on Mars. The scale is 1:200 000 and the height difference between the contour lines is 250 metres. The data were obtained by the High Resolution Stereo camera on board ESA's Mars Express on 5, 8 and 11 October 2004 (during orbits 0912, 0923 and 0934 of Mars Express).
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: ESA / DLR / FU Berlin (G. Neukum)
High resolution image (2.3 MB)
A smaller scale topographic map of the Iani Chaos region on Mars. The scale is just 1:100 000 and the contour lines are finer, just 100 metres difference, to help bring out more subtle gradations in the height of Martian surface features. The data were obtained by the High Resolution Stereo camera on board ESA’s Mars Express on 5, 8 and 11 October 2004 (during orbits 0912, 0923 and 0934 of Mars Express).
Image Credit: Map Compilation: Technische Universität Berlin, 2006; Image Data: ESA / DLR / FU Berlin (G. Neukum)
High resolution image (2.3 MB)
The smallest scale topographic map of the Iani Chaos region on Mars. The scale is just 1:50 000. The contour lines are now only 50 meters apart. At these smaller scales, more textural details of the surface can be recognised. The data were obtained by the High Resolution Stereo camera on board ESA's Mars Express on 5, 8 and 11 October 2004 (during orbits 0912, 0923 and 0934 of Mars Express).
The researchers chose the Iani Chaos region because of its major topographical interest. It is covered in individual blocks and hills that form a chaotic pattern across the landscape.
These 'islands' of rocks are likely all that remains of a previous surface of Mars. The areas in between the islands collapsed when cavities formed below the surface. Initially these cavities may have been supported by the presence of ice, which melted due to volcanic heat. As the water flowed out into Ares Vallis, towards the northern lowlands of Mars, the landscape collapsed and formed the Iani Chaos region we see today.
The contour lines help the eye to understand the morphology of the surface shown in the images. On most of the maps, each line represents a difference of 250 metres in height. The maps also display the names of geographical features and the lines of Martian longitude and latitude.
The maps are a demonstration of the kind of products that can be derived from the HRSC experiment. The HRSC is on the way to providing enough data to create such maps for the whole of Mars. This would generate 10 372 particular map sheets, each covering an equal area of the Martian surface. The maps would be to a scale of 1:200 000.
European Space Agency News Release
