| Ultimi arrivi - Mars Reconnaissance Orbiter (MRO) |
Craters-Unnamed_Crater_with_Gullies.jpgGullies, from MRO56 visitenessun commentoMareKromiumNov 11, 2006
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Deimos-PIA02699.jpgDeimos, from MRO59 visiteCaption NASA originale:"This image showing the position of the Martian moon Deimos against a background of stars is part of a successful technology demonstration completed by NASA's MRO before arrival at Mars. The spacecraft's Optical Navigation Camera (ONC) was used in February and March 2006 to demonstrate the use of pictures from a small camera for calculating precise location of a Mars-bound spacecraft by comparing the observed positions of Mars' two moons to their predicted positions relative to background stars. While this technique was not necessary for the Mars Reconnaissance Orbiter's own navigation, the demonstration prepares the way for relying on it for navigating precise arrivals for future missions that land on Mars.
This example image from the ONC was taken on March 6, 2006, at a distance of 1,08 MKM (about 671.000 miles) from Deimos. That moon, the smaller of Mars' two, has a diameter of about 15 Km (approx. 9 miles), and orbits 23.459 Km (approx. 14.577 miles) above Mars' surface".Ott 27, 2006
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Juventae_Chasma_12m-02.jpgFeatures of Juventae Chasma (3)54 visitenessun commentoOtt 26, 2006
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Juventae_Chasma_12m-01.jpgFeatures of Juventae Chasma (2)54 visiteCaption NASA originale:"Among the more interesting aspects of this image are the dunes of sand that appear to be migrating over the top of the mound, and a flat-surfaced, plateau/mesa forming unit covering the North-East side of the mound but also seen within valleys to the North and along the Southern margin of the mound. This unit may be the marker of an ancient erosional surface. In this image, North is towards the top and the Sun is coming from the left".Ott 26, 2006
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Juventae_Chasma_12m-00.jpgFeatures of Juventae Chasma (1)54 visiteCaption NASA originale:"This image shows a mound of layered rock within the large depression Juventae Chasma (3,5° South Lat. and 61,9° West Long.) known from data from the Omega spectrometer on the Mars Express mission to have sulfate minerals mixed within it. The clear expression of layering in the CTX image and the potential for correlation with MRO-CRISM hyper-spectral data open the possibility of relating specific beds to specific compositions, indicating the nature of the depositional environment and subsequent alteration". Ott 26, 2006
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TRA_000828_1805_IRB-04.jpgYardangs in Medusae Fossae (4)57 visitenessun commentoOtt 22, 2006
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TRA_000828_1805_IRB-03.jpgYardangs in Medusae Fossae (3)62 visitenessun commentoOtt 22, 2006
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TRA_000828_1805_IRB-01.jpgYardangs in Medusae Fossae (1)55 visiteThis series of 4 images covers a portion of an outcrop of the Medusae Fossae Formation, a series of light-toned terrains in the Martian Mid-Latitudes. The Medusae Fossae has been and remains one of the most enigmatic features on Mars. The unit is characterized by wind-sculpted landforms, most notably eroded ridges known as yardangs. The composition of the Medusae Fossae is not known, but candidates include indurated (hardened) volcanic ash or remnants of dust-ice mixtures that formed in a different Martian climate. This HiRISE image reveals new details of the Medusae Fossae. Ott 22, 2006
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TRA_000828_1805_IRB-02.jpgYardangs in Medusae Fossae (2)56 visiteImage TRA_000828_1805 (here broken in 4 sub-images) was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on September 30, 2006. The full image is centered at 0,5° North Latitude and 142,1° East Longitude.
The images are oriented such that North is towards the top. The range to the target site was 270 Km (about 169 miles). At this distance the image scale is 27 cm/pixel (with 1 x 1 binning) so objects ~81 cm across are resolved. The image was taken at a local Mars time of 03:27 PM and the scene is illuminated from the west with a solar incidence angle of 55,2°, thus the Sun was about 34,8° above the horizon.
At a Solar Longitude of 113,6° the season on Mars is Northern Summer.Ott 22, 2006
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North_Polar_Regions-Chasma_Boreale-PIA01926-det.jpgThe Walls of Chasma Boreale80 visiteThe Martian terrain in this remarkable image is at the head of a large chasm, named Chasma Boreale, which cuts through Mars' North Polar Layered Deposits (MNPLD). These ice-rich layered deposits are about 3000 mt (about 9.800 feet) thick and 1000 Km (1.600 miles) across, much like the Greenland ice-sheet on Earth. The head of Chasma Boreale ends in a steep icy cliff more than 1000 mt (about 3300 feet) high. The cliff has both light- and dark-toned layers, seen at right in this image. The image was taken by the HiRISE camera on NASA's MRO. The internal layers of the ice-sheet are visible in the cliff walls. The dark-toned flat area in the center and left of the image is the floor of this chasm, which contains many craters.
Scientists have proposed that Chasma Boreale was formed by a catastrophic flood that began under the ice-sheet and was later widened by wind erosion. However, the large number of craters on the chasm's floor implies that the floor is much older than the ice sheet. These craters should have been removed by the suggested flood; their presence has caused some Mars researchers to instead speculate that no large flood occurred and that Chasma Boreale was not covered with very much ice.
In addition to layered ice, there is also some material within the north polar layered deposits that appears to be composed of sand. The dark material near the base of the cliff wall is thought to be aprons of debris being eroded from sand-rich layers. Zooming in on this dark material with HiRISE reveals ripples, which are diagnostic of moving sand.
Some bright spots of material visible on the cliff wall were not present in previous years. These are likely patches of water frost. Each year layers of carbon dioxide and water frost coat this terrain before being removed during the summer. The water frost lasts longer, and patches that are shaded by nearby steep topography (such as this one) can persist even into late summer.
An unexpected surprise, not visible with previous camera resolutions, is the fragmentation of the exposed surfaces of these icy layers into polygonal blocks. These blocks appear to be breaking away from the layer margins and forming boulder-sized debris, which then rolls down slope (a process called mass-wasting). These boulders are likely to be large blocks of dusty water ice; once separated from the main ice-sheet they can be eroded away by sunlight. More boulder-sized objects are visible out in the floor of the chasm. Polygons are also visible throughout the chasm floor, indicating that water-ice is just below the surface.
Image TRA_000845_2645 was taken by the HiRISE camera on Oct. 1, 2006. The complete image is centered at 84.6 degrees latitude, 3.4 degrees east longitude. The range to the target site was 316 kilometers (198 miles). At this distance the image scale is 63 centimeters (25 inches) per pixel (with 2 x 2 binning), so objects about 186 centimeters (73 inches) across are resolved. The image shown here has been map-projected to 50 centimeters (20 inches) per pixel. North is up. The image was taken at a local Mars time of 3:34 p.m. and the scene is illuminated from the west with a solar incidence angle of 62.3 degrees, thus the sun was about 27.7 degrees above the horizon. At a solar longitude of 114.3 degrees, the season on Mars is northern summer. Ott 21, 2006
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TRA_000840_2750_IRB-008.jpgChasma Boreale (7)57 visitenessun commentoOtt 21, 2006
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TRA_000840_2750_IRB-007.jpgChasma Boreale (6)55 visitenessun commentoOtt 21, 2006
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