Newswand: For the first time Mars Express’ High Resolution Stereo Camera (HRSC) has taken an unprecedented images of Mars and the scientists have developed a mosaic of the planet. Till now we have been seeing only a red globe of Mars. But the new mosaic would provide vivid picture of Mars I different colors.
To mark the 20th anniversary of the launch of the European Space Agency (ESA) Mars Express spacecraft, the High Resolution Stereo Camera (HRSC) science team is announcing the upcoming release of a global colour mosaic of Mars that is unparalleled in the accuracy of its colour information and provides insight into the diverse composition of rock, sand and dust on the surface.
Exactly 20 years ago, on 2 June 2003, the Mars Express spacecraft, the first European mission to explore another planet in the Solar System, launched on a Soyuz launch vehicle from the Baikonur Cosmodrome in Kazakhstan.
The mission was originally only supposed to last one martian year (approximately two Earth years), but the success of the instruments, which continue to work flawlessly, has prompted the European Space Agency (ESA) to extend the mission again and again, most recently until the end of 2026. On 19 October 2023, Mars Express will have orbited Mars 25,000 times in its elliptical orbit.
To acquire its usual surface images, the HRSC normally photographs Mars from an altitude of approximately 300 kilo meters, at roughly the point in its elliptical orbit at which the Mars Express spacecraft is closest to the planet. The resulting views of the martian surface have a spatial resolution of up to 12.5 meters per pixel and cover areas approximately 50 kilo meters wide. Thanks to its four colour channels (red, green, blue, infrared) and five panchromatic nadir, stereo and photometric channels, the stereo camera can visualise Mars in three dimensions and also in colour.
For the global data product presented here, however, 90 individual images were used, taken from higher altitudes (between roughly 4000 and 10,000 kilo meters) above the martian surface and thus covering areas approximately 2500 kilo meters wide on average and at lower spatial resolution (between 200 and 800 metres per pixel). Such large-scale images are typically acquired to observe weather patterns on Mars. But if no clouds or other atmospheric phenomena are visible on the images, they are excellent for creating global views of the martian surface.
It is well known that most of Mars is reddish in colour, due to the high amount of oxidised iron in the dust on its surface, earning it the nickname the ‘Red Planet’. But it is also immediately noticeable that a considerable region of Mars is rather dark, appearing bluish in colour. These regions represent greyish-blackish-bluish sands, which are volcanic in origin and form large, dark sand layers on Mars. These unweathered sands consist of dark, basaltic minerals, of which volcanic lava on Earth is also composed. Basalt is the most widespread volcanic rock on Earth – and in the Solar System. Earth’s ocean floor is made of basalt, as are the extinct volcanoes of the Eifel, Mount Etna in Sicily and volcanoes of the Hawaiian archipelago.
Volcanic material on Mars that has been weathered by water, on the other hand, tends to take on lighter shades over time. For example, clay and sulphate minerals – the two most common minerals on Mars formed through the contact of cooled lava and water – appear particularly bright on such colour composites and are relatively easy to recognise on closer inspection.
Large deposits of light-coloured sulphate minerals such as gypsum (calcium sulphate) or kieserite (magnesium sulphate) can be seen in this mosaic within the Valles Marineris canyon system (image 4) – a vast rift valley over 4000 kilo meters long and stretching along the martian equator. Here, they are covered by a thin veneer of dark sand and thus only reveal their impressive colour variations on closer inspection made using the HRSC. Sulphate minerals indicate environmental conditions at low, acidic pH values, which are less accommodating to life.
The faint, bright and light blue areas depict clouds in the atmosphere). Images containing clouds could not be entirely avoided in the creation of this first version of the global Mars mosaic. The depths of Valles Marineris are also overlaid with atmospheric phenomena. However, these represent fog and haze, which often form within depressions at certain times of the day and year.
The development of the colour model method and processing of the mosaic was performed by Greg Michael, who is part of the HRSC team at Freie Universität Berlin. The planning and acquisition of the high-altitude images were the responsibility of the camera operations team at the German Aerospace Center (DLR) at Berlin-Adlershof. On publication of the upcoming scientific paper on the mosaic, the georeferenced dataset will be made available through the ESA guest storage facility.
Ends…
News Wand 