Mars Reconnaissance Orbiter (MRO) |
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"8"! (Natural Colors; credits: Lunar Explorer Italia)18 visteThis image shows two craters in the Southern Hemisphere just South of Sirenum Fossae.
The Northern Crater (the one that is an upper position) is smaller, appears more degraded, and is partially filled with sediments that form a hummocky surface. Dunes have formed subsequently on this Surface. Some incipient gully-like features have formed midway along the Southern Crater Wall and expose Layers that are more resistant to erosion.
The larger crater to the South is eroded by Gullies on its Northern Slope while the Southern Slope Region lacks them. Most Gullies in this scene appear to emanate from more resistant Layers, although the larger Gullies have eroded back almost to the Crater Rim.
The nature of the Layers and their connection to the water that formed the Gullies is unknown.
Gullies typically form when flowing water erodes sediments and soft rocks in a channelized flow. Because Mars is very cold and dry, it is unknown where the water came from to form the Gullies.
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"Apparent Valley", West of Ganges Chasma (natural colors; credits: Lunexit)51 visteThis image shows an "Apparent Valley" North of a 37-Km long pit called Ophir Cavus. This valley is just West of another 155-Km long valley system called Allegheny Vallis, that also emanates from the pit.
The association of valleys with the pit suggests that water was released when the pit formed, perhaps when volcanic eruptions melted ice in the surface or subsurface.
The HiRISE image reveals light-toned units along portions of the plains and these could be minerals deposited by the flowing water or alteration of the plains by the water that once flowed here.
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"Bullseye" Crater in Elysium Planitia38 visteThe sequence of events that formed this scene in the Equatorial Lowlands of Mars are as follows. First, a meteorite impact excavated the 2,2 Km (about 1,4 mile) diameter crater in the center of the picture. Second, the area was flooded by a vast lava flow. However, the lava was not able to overtop the rim of the crater and it remained a large depression.
Third, the area was blanketed by a series of layers of small particles carried by the wind. This deposit makes up what is called the Medusae Fossae Formation and may be composed of volcanic ash. Finally, the Medusae Fossae Formation was largely eroded away by the wind. However, the deposits within the crater were protected from the wind and have remained to this day.
The hills outside the crater are also remnants of the Medusae Fossae Formation.
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"Fresh" Crater and unusual surface details in Hesperia Planitia (context image)25 visteCaption NASA originale:"Image TRA_000882_1595 was taken by the High Resolution Imaging Science Experiment (HiRISE) camera onboard the Mars Reconnaissance Orbiter spacecraft on October 4, 2006. The complete image is centered at 20,3 South Lat. and 111,2° East Long. The range to the target site was 255,5 Km (such as about 159,7 miles). At this distance the image scale ranges from 25,6 cm/pixel (with 1 x 1 binning) to 51.1 cm/pixel (with 2 x 2 binning). The image shown here has been map-projected to 25 cm/pixel and North is up.
The image was taken at a MLT of 15:30 and the scene is illuminated from the West with a solar incidence angle of 67°, thus the Sun was about 23° above the horizon.
At a Solar Long. of 115,7°, the season on Mars is Northern Summer.
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"Fresh" Crater and unusual surface details in Hesperia Planitia (detail mgnf)32 visteIl rilievo la cui albedo è tale da renderlo visibile anche in un'area ombreggiata (Sx del frame) non è risolvibile e, purtroppo, rimane inesplicabile; il rilievo posto a Dx, invece, lo risolviamo, applicando un ultra-detail mgnf, in un "boulder colonnare" (una surface feature spettacolare e molto rara, ma non necessariamente una Surface Anomaly in senso tecnico.
Semmai, ci domandiamo "da dove" possa provenire il boulder colonnare in oggetto e la nostra ipotesi è che potrebbe trattarsi di un ejecta.
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"Hot Surprise" in Nia Vallis (EDM - credits: Dr M. Faccin)76 visteUn inconfondibile "segno di calore" è apparso in quelle che, a nostro parere, sono le immediate vicinanze della Superficie: una piccola "fiamma" che, se non altro nella sua forma (a "Fiaccola", o "Flare"), nelle sue dimensioni (siamo nell'ordine del metro o poco più) e colore (la Fiaccola, guarda caso, è "Blu"...), ci ricorda la fantomatica Blue Flare che tanto ha intrigato ed intriga i Ricercatori di Anomalìe Lunari.
In questo frame, la nostra piccola "Blue Flare" aleggia/emerge sulla/dalla Superficie di Nia Vallis o nelle sue immediatissime vicinanze (ossìa potrebbe librarsi a pochi metri dal suolo).
La configurazione del dettaglio - una volta escluso l'image-artifact - ci suggerisce l'eventualità per cui si possa trattare di un fenomeno equiparabile ai cosiddetti "fuochi fatui", di terrestre (e, spesso, "lugubre") memoria, ossìa combustione di modesti quantitativi di gas derivanti da decomposizione di elementi organici (usualmente si tratta di Metano o Fosfano).
I luoghi "preferiti" per la verificazione di questo tipo di fenomeni sono i cimiteri, le aree ricche di acque stagnanti o semi-stagnanti (paludi e stagni) e le brughiere.
In questo caso...siamo su Marte e quindi, tutto sommato, i cimiteri ci sentiamo di escluderli come possibile causa della Flare.
Ed anche la brughiera non sembra un luogo attinente, vista la regione sorvolata dalla Sonda.
Ma come escludere la presenza di acque stagnanti sub-superficiali, magari ricchissime di elementi organici?
Cosa c'è - REALMENTE - nel sottosuolo di Marte?
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"Hot Surprise" in Nia Vallis (ctx frame - Natural Colors; credits: Lunexit)28 visteImmagini orbitali come questa, nel 99,99% dei casi passano del tutto inosservate ma, come Voi sapete (e come noi abbiamo - da tempo - imparato), spesso le più grosse sorprese si annidano tra le pieghe dei frames - apparentemente - meno intriganti.
In fondo, che cosa ci mostra di particolare questo frame? Si tratta della Regione Marziana di Nia Vallis (siamo nelle medie Latitudini dell'Emisfero Australe di Marte, intorno alle coordinate 53° Sud e 323° Est) ed il dettaglio colto dagli occhi della Sonda MRO ci mostra quelli che sembrano residui di antiche (ed ormai del tutto estinte) attività fluviali su una superficie rocciosa e ricca di macigni di dimensioni medio-piccole. Nulla di più.
Eppure, una volta che il nostro Dr Faccin ha "scansionato" il frame nella sua versione JP2000, qualcosa è emersa.
Qualcosa che vedrete nel prossimo frame...
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"Slab" of Layered Material in Aureum Chaos (MULTISPECTRUM; credits: Lunexit)41 visteThis image shows a large outcrop of layered rock in Aureum Chaos, an area that has apparently collapsed, leaving a region of irregular knobs and hills. Unlike many of the knobs, the light outcrop shows distinct, nearly horizontal layers. This may indicate that it was deposited after the collapse of the Chaos.
Multiple layers are exposed in the outcrop, which is several Kms long. The best exposures, in the North Wall (Sx), reveal multiple different rock units with different color and texture. The bottom unit (Dx) is very light-toned and shows little internal structure other than occasional fractures. Above this is a darker unit with a broken appearance, followed by fine, stepped layers. The top of the outcrop consists of knobs and spires that may be eroded remnants of the top of the stack. Many of the units show variations in color which could indicate further divisions.
This package of rocks may have been deposited by multiple processes. Alternatively, the same process could have delivered sediments from different sources. Some possible origins include dust or volcanic ash settling from the atmosphere, wind-blown sand, or material deposited in lakes.
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"Worm-like" Surface Feature in the Southern Highlands (EDM - Natural Colors; credits: Lunexit)50 vistenessun commento
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"Worm-like" Surface Feature in the Southern Highlands (EDM n. 2 - False Colors; credits: Dr G. Barca)49 visteRingraziando gli Amici di Lunexit per gli interessanti commenti, dobbiamo precisare (onde evitare l'insorgere di spiacevoli malintesi) che, a nostro parere, questa Surface Feature non possiede nulla di "Biogenico".
Si tratta, sempre a nostro modo di vedere, del letto asciutto di un antichissimo torrente (o forse anche un laghetto, le cui acque erano comunque soggette a deboli correnti).
L'apparenza - da svariate centinaia di Km di altezza - è quella di un grosso "vermone", ma la sostanza ci dice che siamo davanti ad un antico rilievo di presumibili origini fluviali, sinuoso e (ovviamente) prosciugato, sul quale si elevano delle bizzarre (e sempre affascinanti) "ripples".
Relativamente a queste ripples, da notare la loro albedo (elevata) e la loro forma a "scafo", la cui origne, con ogni probabilità, può essere fatta risalire all'azione congiunta di correnti d'aria persistenti e periodicamente contrapposte.
La loro consistenza, a nostro parere, dovrebbe rendere queste ripples simili in tutto e per tutto a quei rilievi rocciosi - ma fragili - che prendono il nome di "yardangs".
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"Worm-like" Surface Feature in the Southern Highlands (ctx frame - Natural Colors; credits: Lunexit)30 vistenessun commento
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(Almost) Silent Rolling Stones in Kasei Valles13 visteScene PSP_001640_2125 shows the very steep side of a plateau, part of the Northern limit of the Kasei Valles System, which is one of the largest outflow Channel Systems on Mars.
The difference in elevation here between the mostly flat channel's floor (Sx and the bottom of the picture) and the top of the plateau (Dx) is over 1300 mt, comparable in height to the Grand Canyon walls.
The Kasei Valles System is much wider than the Grand Canyon, though, getting to be in places 500 Km wide (the Grand Canyon's maximum width is 30 Km).
Some of these blocks traveled downhill several hundred meters as they rolled and bounced leaving behind a trail of indentations or poke marks in the surface's fine-grained, light-toned soils. The raised borders in some of these poke marks indicate they are relatively recent features, unaffected by wind erosion, or that this soil has cohesive properties, such as if it was cemented.
The sound of these blocks falling did not travel very far, though. According to computer simulations sound in Mars travels only 1,5% the distance it would travel on Earth (no Martian sound has ever been recorded). Hence, the same sound which would travel 1 Km (0,6 miles) on Earth would travel only 15 mt (16 yards) on Mars. This is due to the lower Martian atmospheric pressure, which is approximately 1% of that of Earth.
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