|Perspective view. Solis Planum images were taken during orbit 431 in May 2004 with a ground resolution of approximately 48 meters per pixel. The displayed region is located south of Solis Planum at longitude 271° East and latitude of about 33° South. |
Credit: ESA/Mars Express
These images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show part of a heavily eroded impact crater at Solis Planum, in the Thaumasia region of the southern hemisphere.
The larger eroded impact crater in the lower left of this image has a diameter of about 53 kilometers (32 miles) and its eastern crater rim is about 800 meters (0.5 miles) high. The blue/white tint in the eastern (top left) part of the scene indicates a near-surface haze or clouds.
To the south (right), tectonic ‘graben’ structures can be seen running in three different directions (north-west, north-east and east-north-east), which show three different phases of development.
A graben is a down-dropped block of the crust resulting from extension, or pulling, of the crust. They are often seen together with features called ‘horsts’, which are upthrown blocks lying between two steep-angled fault blocks. Some of the graben shown here are about five kilometers (3 miles) wide. The northern end of the higher region, or upper left in this image, contains an almost circular plateau, which is 15 kilometers (9 miles) across.
|Top view. Solis Planum images were taken during orbit 431 in May 2004 with a ground resolution of approximately 48 meters per pixel. The displayed region is located south of Solis Planum at longitude 271° East and latitude of about 33° South. Credit: ESA/Mars Express|
It may be an old impact crater, filled by sediments, which developed a harder consistency than the surrounding material over the course of time. Later, the more easily eroded material was removed and the harder inner filling remained. This phenomenon is called ‘inverted relief’.
Mars Express is so called because it was built more quickly than any other comparable planetary mission. Mars Express’s design and development phase took about five years, compared with about ten years for previous similar missions. Before the camera team can lay their hands on the pictures, the data have to make the long journey back home. After the pictures are taken and stored on board Mars Express, the data is transmitted to ESA’s New Norcia Station in Australia, or to NASA’s Deep Space Network Station in Madrid. From there, the data are collected at the European Space Operations Centre (ESOC) at Darmstadt in Germany. They are then transmitted to the German Aerospace Research Establishment (DLR) in Berlin, where most of them will be processed into the pictures we see.
It usually takes between four and seven days for a picture to be ‘ready’. Depending on the picture size, analysis objective and the amount of computer capacity available, this period can easily stretch to ten to fourteen days. These techniques are still very new and recently gained knowledge and experience has often meant that more-expensive picture processing is required. From the start of January to the middle of February, Mars Express produced a total of 18 strips of pictures in 100 orbits of Mars. In general, one orbit produces an image with a length of over 250,000 lines, sometimes more, sometimes less.
|Perspective view. Solis Planum images were taken during orbit 431 in May 2004 with a ground resolution of approximately 48 meters per pixel. The displayed region is located south of Solis Planum at longitude 271° East and latitude of about 33° South.|
Credit: ESA/Mars Express
From orbit, Mars Express is scanning the surface and atmosphere of the planet with seven instruments. In particular it will:
- search for signs of water down to a few kilometres underground;
- map the Martian surface more accurately than ever before (in colour and stereo);
- determine the detailed composition of the surface;
- determine the composition and circulation of the atmosphere;
- study the interaction of the solar wind with the planet.
Mars Express is performing the most detailed and complete exploration of Mars ever done. When searching for water, for instance, Mars Express is conducting the most thorough search so far: from several kilometers below the ground, and up into the atmosphere. Before entering martian orbit, the cruise took just over six months. Mars Express travelled at an average speed of about 10 kilometers per second (around 2100 miles per hour) and covered a distance of about 400 million kilometers (240 million miles).
Mars Express’s orbiter will operate for a whole Martian year (687 Earth days). It is expected that the mission will be extended by another Martian year. After the mission, the Mars Express orbiter will simply keep orbiting the planet for at least 50 years. Then it will probably burn up in Mars’s atmosphere. This will also ensure that debris will not pollute the planet’s surface. Many of Mars Express elements will be used for Venus Express, and probably other missions in the future.