A Tribute To Mars Global Surveyor
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Craters-Eberswalde_Crater-2-PIA04293_fig2.jpgEberswalde Crater and Delta in HR54 visiteOriginal caption:"Additional images from MOC provide some context and show a nearby portion of the fossil delta's inverted channels at a spatial scale of 1,5 mt (about 5 feet) per pixel. The relative positions of these 3 images are indicated in a mosaic image of the entire delta - picture (1). The first MOC narrow angle images of some of the landforms in the delta were acquired in 2000, during the MGS primary mission, but those pictures did not show very well the unambiguous inverted channel forms. Not until the second Earth year of the orbiter's extended mission were the deltaic features recognized in MOC images obtained in March and June of 2002.
Following the initial observations in 2002, the MOC Team began a systematic effort to map the entire Eberswalde Crater delta. Most of this imaging required slewing the whole spacecraft in a technique called "roll only targeted observation" so that it pointed the camera toward the feature. In this way, the camera team was able to build up a mosaic of the delta much more quickly than would have been the case if the team had simply relied upon chance crossing of the delta by the orbiter's usual ground track. This technique was not employed during Mars Global Surveyor's primary mission, except in the search for Mars Polar Lander, but became a routine part of the tool kit during the extended mission".
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Craters-Eberswalde_Crater-4-PIA04293_fig3.jpgEberswalde Crater and Delta (Sub-meter-per-pixel cPROTO - detail mgnf)54 visiteOriginal caption:"Even with the roll only targeted observation technique, it took more than one Earth year to build up a complete mosaic of images of the delta. In the meantime, the first data showing the deltaic landforms were archived and released to the public and scientific community, long before the MOC Team's analysis and mosaic were complete. Some scientists began independent analyses of the landform at that time. The initial analysis and announcement of the feature was finally published in November 2003.
The Eberswalde delta provides the first clear, 'smoking gun' evidence that some valleys on Mars experienced persistent flow of a liquid with the physical properties of water over an extended period of time, as do rivers on Earth. In addition, because the delta today is "lithified" - that is, hardened to form rock - it provided the first unambiguous evidence that some martian sedimentary rocks were deposited in a liquid (presumably, water) environment. The presence of meandering channels, a cut-off meander, and crisscrossing channels at different elevations (one above the other), provided the clear geologic evidence for these interpretations".
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Craters-Eberswalde_Crater-5-PIA04293_fig3.jpgEberswalde Crater and Delta (Sub-meter-per-pixel cPROTO - detail mgnf)56 visiteOriginal caption:"After the sediments were deposited to form the delta, the material was further buried by other materials - probably sediments - that are no longer present. The entire package of buried material became cemented and hardened to form rock. Later, erosive processes - such as wind - stripped away the overlying rock, re-exposing the delta. Now preserved essentially as a fossil, the former floors of channels in the delta became inverted, to form ridges, by erosion. Channels can be inverted by erosion on both Earth and Mars. Usually this happens when the channel floor, or the material filling the channel, is harder to erode than the surrounding material into which the channel was cut. In some cases, the channels on Earth and Mars have been filled by lava to make them more resistant to erosion. In the case of Eberswalde, there are no lava flows; instead, the channel floors may have been rendered resistant to erosion either by being better-cemented than the surrounding material, or composed of coarser-grained sediment (such as sand and gravel as opposed to silt), or both".
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Craters-Exhumed_CFrater_in_Vastitas_Borealis-PIA03926-01.jpgA very unusually-looking Exhumed Crater (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunexit Team)139 visiteCaption NASA originale:"This MGS-MOC image shows a circular feature on the Martian Northern Plains. It was once a crater formed by meteoritic impact. It was completely filled and buried by and within layered material. Later, the layered materials have begun to be eroded away, re-exposing the old crater rims in the process".
Location near: 44,9° North Lat. and 264,7° West Long.
Image width: ~3 Km (~1,9) mi
Illumination from: lower left
Season: Northern Autumn
Nota: a giudicare dalle fattezze emergenti dalle sabbie, più che un antico cratere sepolto ed ora in corso di 'riesumazione', diremmo che potrebbe trattarsi di un modesto rilievo vulcanico (un "camino" infossato), caratterizzato da un discreto numero di caldere. Certo, non si è mai sentito parlare di un 'vulcano sepolto' e poi riportato alla luce dal concorso degli agenti geologici ed atmosferici ma, in fondo, anche le ipotesi più 'sfrontate', alle volte, possono rivelarsi esatte. MareKromium
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Craters-Exhumed_Crater_in_Vastitas_Borealis-PIA03926-00.jpgA very unusually-looking Exhumed Crater (Original NASA/MGS/MSSS b/w Frame)58 visiteCaption NASA originale:"This MGS-MOC image shows a circular feature on the Martian Northern Plains. It was once a crater formed by meteoritic impact. It was completely filled and buried by and within layered material. Later, the layered materials have begun to be eroded away, re-exposing the old crater rims in the process".
Location near: 44,9° North Lat. and 264,7° West Long.
Image width: ~3 Km (~1,9) mi
Illumination from: lower left
Season: Northern Autumn
Nota: a giudicare dalle fattezze emergenti dalle sabbie, più che un antico cratere sepolto ed ora in corso di 'riesumazione', diremmo che potrebbe trattarsi di un modesto rilievo vulcanico (un "camino" infossato), caratterizzato da un discreto numero di caldere. Certo, non si è mai sentito parlare di un 'vulcano sepolto' e poi riportato alla luce dal concorso degli agenti geologici ed atmosferici ma, in fondo, anche le ipotesi più 'sfrontate', alle volte, possono rivelarsi esatte.
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Craters-Galle_Crater-3D.jpgLayers of Galle Crater (3D - credits: NASA/JPL/MSSS)54 visiteCaption NASA:"This is a 3-D stereo anaglyph showing layers in Galle Crater. This anaglyph uses two MGS-MOC images acquired at slightly different viewing angles: MOC images E22-01557 and M14-02055. Owing to the specifics of the viewing geometry, the image is tilted on its side, relative to the mosaic shown in the 15 June 2006 release. In other words, in this image, North is toward the right and West is up. This anaglyph, when viewed in conjunction with the 15 June 2006 mosaic of these layers, provides a more complete sense of the cross-cutting relations between layers in the mound located in southern Galle (Happy Face) Crater. The layers are part of a mound of sedimentary rock in southern Galle — a remnant of a once more-extensive deposit of sedimentary material in this south mid-latitude impact basin.
Location near: 52,3° South Lat. and 30,1° West Long.
Image width: ~7,3 Km (~4,5 mi)
Illumination from: upper right
Anaglyph from MOC images: E22-01557 and M14-02055
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Craters-Galle_Crater-Happy_Face_Crater-2003_05_15_M2300366.jpgGalle Crater (Natural Colors; credits: NASA/MGS/MSSS)84 visiteCaption NASA originale:"The 2 pictures shown here are taken from the same daily global image mosaic (the only difference is that each was processed slightly differently). The pictures show Galle Crater, informally known as "Happy Face," as it appeared in early Southern Winter. The white-ish gray surfaces are coated with wintertime carbon dioxide frost. The pattern of frost distribution gives the appearance that "Happy Face" has opened its mouth. Galle Crater is located on the east rim of Argyre Planitia at 51°S, 31°W. Sunlight illuminates the scene from the upper left. Galle Crater is about 230 Km (143 mi) across".
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Craters-Galle_Crater-Happy_Face_Crater-MGS-2.jpgGalle Crater (Saturated Natural Colors; credits: NASA/MGS/MSSS)103 visiteIl nome che è stato dato al cratere qui ripreso dal Mars Global Surveyor spiega già tutto: da questa angolazione, infatti, si potrebbe dire che un dotato burlone sia andato a disegnare un bel "viso sorridente" sulla superficie di Marte. Ovviamente si tratta di un semplice effetto ottico determinato dalla particolare prospettiva in cui si trovava la Sonda rispetto al cratere nel momento della ripresa.
Eppure - credeteci! - c'è stato qualcuno che ha pensato che questa "Faccia Felice" fosse un altro degli enigmatici "Monumenti di Marte", dopo la Sfinge e le Piramidi di Cydonia Mensae.
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Craters-Gusev_Crater-R1300473_474.jpgGusev Crater Landscape from MGS (Extremely Enhanced Natural Colors; credits:NASA/JPL-MSSS)123 visiteSi tratta di un'immagine a colori ad HD semplicemente fantastica, ottenuta dalla Sonda Mars Global Surveyor e relativa (in parte) all'area di lavoro di Spirit. Abbiamo scelto di mostrarVi questo frame per almeno 3 buoni motivi: 1) perchè si tratta di un frame bellissimo; 2) perchè ci fa vedere bene i "colori di Marte" (che, dall'alto, sembrano diversi da quanto ci mostrano le Sonde che stazionano sulla superficie e 3) perchè ci aiuta a cogliere, usando i nostri occhi, la sensazione che proveremmo se ci trovassimo fisicamente su una nave spaziale, in orbita intorno a Marte.
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Craters-Hellespontus_Crater-1-M0201817Det.jpgFrost on the dunes of Hellespontus Crater (Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga - Lunar Explorer Italia)54 visitenessun commentoMareKromium
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Craters-Holden_Crater-3-M0302733.jpgHolden Crater floor near intersection with Uzboi Vallis54 visitenessun commento
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Craters-Holden_Crater-4-M0302733.jpgHolden Crater floor near intersection with Uzboi Vallis54 visitenessun commento
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