| Piú viste - SMART-1: the Moon from ESA |
24-Mare Humorum-2.jpgMare Humorum (2)72 visite...La voglia di commentare questi poveri frames (poveri da svariati punti di vista...) messi a disposizione dall'ESA è forte ma, dato che il commento, in casi come questo, diventerebbe prima ironia e poi sarcasmo, riteniamo più giusto e saggio tacere.
Anzi no, una cosa va detta: se questi frames (assieme ai pochi altri messi a disposizione del Pubblico da parte dell'Agenzia Spaziale Europea in questi mesi) sono il risultato reale del mapping iper-dettagliato della Luna che SMART-1 avrebbe dovuto eseguire, allora ci tocca dire e ribadire che l'ESA ha ancora tantissima strada da percorrere prima di arrivare a produrre qualcosa di decente.
Se invece questi miseri frames sono solo una porzione del lavoro svolto da SMART-1 (come noi riteniamo), ci piacerebbe allora sapere come mai anche la "pacifica ed indipendente" Agenzia Spaziale Europea "gioca a nascondino" con le immagini che arrivano dallo Spazio.
Domande, domande, domande...
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26-Lunar Highlands.jpgLunar Highlands72 visiteThese two images, taken by the advanced Moon Imaging Experiment (AMIE) on board SMART-1, show the difference between lunar highlands and a mare area from close by.
The image on the left, showing highlands, was obtained by AMIE on 22 January 2006, from a distance of about 1112 kilometres from the surface, with a ground resolution of 100 metres per pixel. The imaged area is centred at 26° South and 157° West.
The image on the right, showing a mare, was taken on 10 January 2006, from a distance of about 1990 kilometres and with a ground resolution of 180 metres per pixel. The imaged area is centred at 27.4° North and 0.8° East.
Already when looking at the Moon with the naked eye, it can be seen that there are bright and dark areas on its surface. Centuries ago, the dark areas were called 'maria', presumably assuming that the observer would be seeing water oceans. Today we know that there is no liquid water on our satellite. However, telescopic observations showed that the maria are very flat, and are very different from the so-called highlands. The highlands are heavily cratered and mountainous.
We have learned that the maria are relatively young areas on the Moon which were generated after very large impacts penetrated the lunar crust and excavated basins. During later volcanic episodes, liquid magma came to the surface and filled these basins. When it cooled down and solidified, it formed the large flat areas we can still see today. As this happened in comparatively recent times, the number of impact craters is far less than in the highland areas.
From the two images it is possible to see how highlands present a very irregular topography and many craters, while the mare area is comparatively flat and shows a much smaller number of craters.
The images are raw data and no flat field or other corrections have been applied.
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Z-101-b_Impact_flash_865170.jpgLunar Flash! (detail mgnf)72 visitenessun commento
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33-SulpiciusGallus.jpgSulpicius Gallus' Region71 visiteThis mosaic of three images, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft, shows the area close to the Sulpicius Gallus crater on the Moon.
AMIE obtained this sequence on 18 March 2006, from a distance of 1200 kilometres from the surface, with a ground resolution ranging from 110 to 114 metres per pixel.
The area shown in the top image is centred at a latitude of 19.7º North and longitude 12.2º East; the image in the middle is centred at a latitude of 18.2º North and longitude 12.3º East; the bottom image is centred at a latitude of 16.7º North and longitude 12.5º East.
The prominent crater on the upper left area of this mosaic is called Sulpicius Gallus. It is a fairly fresh, bowl-shaped crater with a diameter of roughly 12 kilometres. The flat lava plains surrounding it belong to the Mare Serenitatis (the 'Sea of Serenity') on the north-eastern side of the Moon facing Earth. The mountains going diagonally through the middle part of the mosaic are called Montes Haemus. They are denoting the edge of the huge impact crater which formed the Mare Serenitatis.
The area around Sulpicius Crater is very interesting for lunar scientists – it is one of the most geologically and compositionally complex areas of the nearside of the Moon. The geologic history of this region has been shaped by impacts of different scales and epochs, by volcanism of variable style and composition with time, and by limited tectonics. Specific findings (Bell and Hawke, 1995) include the detection of relatively fresh highlands materials in the crater.
Good spectroscopic data (that is relative to the mineralogical composition) are available both from the Clementine mission and from ground-based observations, allowing to better constrain the geological evolution of our closest cosmic neighbour.
The area has been suggested to contain mixtures of glassy and black beads generated when large impacts melted part of the lunar surface. However, modelling the spectral properties of material similar to lunar material does not allow to unambiguously match the composition of the material to the measured data.
Colour observations of the AMIE camera will help in further clarifying these issues. So, the combination of high spatial resolution imaging and high spectral resolution spectroscopy from datasets from SMART-1, Clementine and ground based telescopes will finally allow to better model mineral mixtures on the Moon.
The crater Sulpicius Gallus is named after a Roman general, state man and orator. He is famous for having predicted an eclipse of the moon on the night before the battle of Pydna (168 BC). A man of great learning, in his later years he devoted himself to the study of astronomy.
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17-smart20050125a.jpgBrianchon and Pascal67 visiteOriginal caption:"This area of the lunar surface shows the area of the Moon around two large craters. The largest visible in this image is called Brianchon (middle left) and is situated at 75° North Lunar Latitude and 86° West Lunar Longitude. The second largest in this image is called Pascal (middle bottom), at 74° North Lunar Latitude and 70° West Lunar Longitude".
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36-AMI_EAE3_001775_00019_00020_H.jpgCrater Gruithuisen-B and Gruithuisen Montes67 visiteCaption ESA originale:"This image, taken by the Advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft, shows the Gruithuisen Area on the Moon.
AMIE obtained this image on 1 January 2006, from a distance of about 2154 Km from the surface, with a ground resolution of 195 mt per pixel.
The area shown in the image is centred at a Latitude of 34.8º North and Longitude 40º West.
The prominent bowl-shaped crater close to the left edge of the image is Gruithuisen-B. Gruithuisen itself is just visible at the right edge of the image. The mountains visible in the area are called Montes Gruithuisen.
It is possible to note the large number of similar sized craters to the right of the centre of the image. They are so-called secondary craters, produced by ejecta particles from a large impact which fell back to the Moon".
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Z-103-LO_4_148_H3_impact_point_H.jpgThe "Impact Location" (2)67 visiteCaption ESA originale:"The blue star indicates the approximate impact site assuming that the coordinate system used to produce the reference Clementine Base Mosaic is correct. The yellow star indicates the approximate impact site using USGS's lunar control network revised with respect to the Clementine Base Mosaic. The distance separating the blue and yellow stars is about 7 Km.
In this image North is up".
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24-Mare Humorum-5.jpgMare Humorum (5)66 visitenessun commento
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31-Gassendi.jpgGassendi Crater66 visiteCaption ESA originale:"This mosaic of 2 images, taken by the advanced Moon Imaging Experiment (AMIE) on board ESA's SMART-1 spacecraft, shows the inside of crater Gassendi. AMIE obtained these images on 13 January 2006, 1' apart from each other, from a distance of about 1220 Km(top frame) and 1196 Km (bottom frame) from the surface, with a ground resolution of 110 and 108 mt per pixel, respectively.
The area shown in the top image is centred at a Latitude of 16,2º South and Longitude 40,2º West, while the bottom images is centred at a Latitude of 17,9º South and Longitude 40,2º West.
Gassendi is an impact feature located on the Near Side of the Moon, at the Northern Edge of Mare Humorum. The crater is actually much larger than the field of view visible in this image. The hills on the lower right of the mosaic are the central peak of the crater, with a height of roughly 1,2 Km. The crater almost fully visible on the top is called Gassendi A".
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36-Shackleton_Crater-AMI_EAE3_001775_00002_00020.jpgSchakleton Crater in natural colors66 visiteThe Advanced Moon Imaging Experiment Camera (AMIE) obtained this image on 13 January 2006 - close to the time of Lunar Southern Summer - from a distance of about 646 Km over the surface and with a ground resolution of 60 mt per pixel.
Shackleton crater lies at the Lunar South Pole (89,54° S. Lat. and 0° East Lng.) and has a diameter of approx. 19 Km.
SMART-1 monitored this area almost every orbit. This will allow to produce very high resolution maps of the area as well as illumination maps. The long shadows that surround the crater make it very hard to observe. The analysis of the data obtained allowed a very detailed map of its rim, surrounding ejectas and craters.
SMART-1 also made long repeated exposures to see inside the shadowed areas. The purpose was detecting the very weak reflected light from the crater rims, and therefore study the surface reflection properties (albedo) and its spectral variations (mineralogical composition). These properties could reveal patchy ice surface layers inside the crater.
On the 2-kilometre wide inner edge of the crater ridge, at times barely visible from Earth, astronomers using ground radio-telescopes have recently reported they were not able to detect a distinctive signature of thick deposits of ice in the area. Earlier measurements by NASA's Lunar Prospector reported of hydrogen enhancement over large shadowed areas.
"We still do not know if this hydrogen is due to enhanced trapping of solar wind, or to the water ice brought on the Moon by the bombardment of comets and asteroids," says Bernard Foing, ESA's SMART-1 Project Scientist. "These bodies may have deposited on the Moon patchy layers of ice filling about 1.5 percent of the areas in permanent shadow, down to one metre below the surface."
"We need to analyse all remote sensing data sets consistently. Future lander and rover missions to the Moon will help in the search and characterisation of lunar polar ice, both on the surface and below the subsurface," Foing continues. "In any case, one day we may even be able to simply combine the implanted hydrogen and the oxygen extracted from lunar rocks to produce clean water, like we do in laboratory experiments on Earth.”
The crater is named after Ernest Shackleton (1874-1922), an explorer famous for his Antartic expeditions.
MareKromium
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29-KeplerCrater.jpgKepler Crater64 visiteCaption ESA originale:"The imaged area is centred at a Latitude of 37,8º South and Longitude 9,0º East. Kepler is a small young crater situated between Oceanus Procellarum and Mare Insularum. It has a diameter of 32 Km and it is 2,6 Km deep.
Kepler displays a ray system that overlaps with rays from other craters and which extends over 300 Km.
The outer wall of Kepler shows a slightly polygonal shape. The interior walls of the crater are slumped and slightly terraced, and descend to an uneven floor and a minor central rise".
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50-Smart-1_25_August_1348UTC_H.jpgLunar Limb and Stars64 visiteCaption ESA originale:"This image of the Lunar Surface was taken on 25 August 2006 at 15:48 CEST (13:48 UT) by the star tracker (attitude camera) on board ESA's SMART-1, from a distance of 744 Km above the Moon surface.
The spacecraft was travelling at a speed of 1,6 Km/sec..
Remarkably, at the time the image was taken the star tracker was still producing valid attitude samples based on the few stars that are visible in the image.
This image was taken as a test, meaning that the spacecraft pointing was not optimised for star tracker imaging.
The Moon features on the photo still have to be identified".
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