Daily Science Journal (Aug. 2, 2007) — The High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express obtained images of the Tyrrhena Terra region on Mars.
Tyrrhena Terra, perspective view. (Credit: ESA/DLR/FU Berlin (G. Neukum))On 10 May 2007, the pictures of the region located at 18° South and 99° East were taken during orbit number 4294 with a ground resolution of approximately 15 metres per pixel.
Tyrrhena Terra is part of the ancient, heavily cratered southern Martian highlands. The region is located north of Hellas Planitia, the largest impact basin on Mars. The image scene exhibits three impact craters, located at the eastern border of Tyrrhena Terra with Hesperia Planum.
The western part of the scene is dominated by a 35 kilometre-wide and approximately 1000 metre-deep impact crater with an extremely steep rim. The rim rises up to 400 metres above the surrounding plains.
The crater is surrounded by multiple layers of material ejected during the impact. These so called ‘ejecta blankets’ spread up to a distance of 50 kilometres around the crater.
Their round, lobate appearance hints at possible ice- and water-rich subsurface material.
The raised feature in the centre of the crater most likely originated from the elastic rebound of compressed subsurface material after the impact. This feature is called 'central peak' or 'central uplift'. This is comparable to what happens when a drop of water hits a puddle.
Another, 18 kilometre-long and approximately 750 metre-deep impact crater, in all likelihood a ‘double impact crater’, is located south of the large crater.
These ‘double impact craters’ develop when two objects, possibly part of the same fragmented object, hit the surface almost simultaneously.
The impact that formed the larger northern crater, which displays an intact crater wall, occurred after the double-impact crater was formed. The ejecta from this later impact has reshaped the double-impact crater.
The northern part has been filled by ejecta and the material is present even at the bottom of the crater, in the direction of the point of impact (towards the larger, neighbouring crater).
The colour scenes have been derived from the three HRSC colour channels and the nadir channel. The perspective views have been calculated from the Digital Terrain Model derived from the HRSC stereo channels. The anaglyph images were calculated by putting together data from the nadir channel and one stereo channel. The black and white high-resolution images were derived from the nadir channel which provides the highest level of detail.
Adapted from materials provided by European Space Agency.
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Water Ice In Crater At Martian North Pole
New images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole.
The crater is surrounded by multiple layers of material ejected during the impact. These so called ‘ejecta blankets’ spread up to a distance of 50 kilometres around the crater.
Their round, lobate appearance hints at possible ice- and water-rich subsurface material.
The raised feature in the centre of the crater most likely originated from the elastic rebound of compressed subsurface material after the impact. This feature is called 'central peak' or 'central uplift'. This is comparable to what happens when a drop of water hits a puddle.
Another, 18 kilometre-long and approximately 750 metre-deep impact crater, in all likelihood a ‘double impact crater’, is located south of the large crater.
These ‘double impact craters’ develop when two objects, possibly part of the same fragmented object, hit the surface almost simultaneously.
The impact that formed the larger northern crater, which displays an intact crater wall, occurred after the double-impact crater was formed. The ejecta from this later impact has reshaped the double-impact crater.
The northern part has been filled by ejecta and the material is present even at the bottom of the crater, in the direction of the point of impact (towards the larger, neighbouring crater).
The colour scenes have been derived from the three HRSC colour channels and the nadir channel. The perspective views have been calculated from the Digital Terrain Model derived from the HRSC stereo channels. The anaglyph images were calculated by putting together data from the nadir channel and one stereo channel. The black and white high-resolution images were derived from the nadir channel which provides the highest level of detail.
Adapted from materials provided by European Space Agency.
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Water Ice In Crater At Martian North Pole
New images, taken by the High Resolution Stereo Camera (HRSC) on board ESA’s Mars Express spacecraft, show a patch of water ice sitting on the floor of an unnamed crater near the Martian north pole.
Perspective view of crater with water ice - looking east. (Credits: ESA/DLR/FU Berlin (G. Neukum))The HRSC obtained these images during orbit 1343 with a ground resolution of approximately 15 metres per pixel. The unnamed impact crater is located on Vastitas Borealis, a broad plain that covers much of Mars's far northern latitudes, at approximately 70.5° North and 103° East.
The crater is 35 kilometres wide and has a maximum depth of approximately 2 kilometres beneath the crater rim. The circular patch of bright material located at the centre of the crater is residual water ice.
This white patch is present all year round, as the temperature and pressure are not high enough to allow sublimation of water ice.
It cannot be frozen carbon dioxide since carbon dioxide ice had already disappeared from the north polar cap at the time the image was taken (late summer in the Martian northern hemisphere).
There is a height difference of 200 metres between the crater floor and the surface of this bright material, which cannot be attributed solely to water ice.
It is probably mostly due to a large dune field lying beneath this ice layer. Indeed, some of these dunes are exposed at the easternmost edge of the ice.
Faint traces of water ice are also visible along the rim of the crater and on the crater walls. The absence of ice along the north-west rim and walls may occur because this area receives more sunlight due to the Sun’s orientation, as highlighted in the perspective view.
The colour images were processed using the HRSC nadir (vertical view) and three colour channels. The perspective views were calculated from the digital terrain model derived from the stereo channels.
The 3D anaglyph images were created from the nadir channel and one of the stereo channels. Stereoscopic glasses are needed to view the 3D images Image resolution has been decreased for use on the internet.
Adapted from materials provided by European Space Agency.
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