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| Piú votate - Titan: The "Foggy" Moon |
Titan-Surface-40.gifOn the Surface... - Sol 1 (GIF-Movie; credits: Dr G. Barca)58 visiteIl quantitativo di luce solare e di calore che raggiunge la superficie di Titano (la cui temperatura superficiale media, lo ricordiamo, si aggira, per quanto si sa e si suppone, intorno ai -175° Celsius) infatti, è talmente esiguo (diciamo pure “trascurabile”) da non permettere – se non altro sulla base di quelle che sono le nostre attuali conoscenze scientifiche – lo sviluppo di alcuna reazione assimilabile, ad esempio, alla fotosintesi.
Questo significa, tra le altre cose, che l’eventuale sviluppo di Forme Vitali indigene su Titano potrebbe derivare esclusivamente da interazioni chimiche o da processi esotici di carattere assolutamente locale. A quest’ultimo proposito, infine, si è detto e scritto che Titano, in fondo, rappresenta la versione “gelida” di una Terra Primordiale (un parallelo nato, probabilmente, dalla considerazione relativa al quantitativo di Nitrogeno esistente nell’atmosfera della Luna Nebbiosa nonché in riferimento a quella che sembra essere la morfologia attuale del pianeta in rapporto a quella che si suppone possa essere stata la morfologia della Terra Primordiale).
A nostro parere, però, la realtà è diversa e Titano potrebbe rappresentare, oggi, l’espressione di un Mondo “vivo e vitale” per nulla simile od assimilabile al nostro Pianeta Azzurro.
Un mondo che NON assomiglia affatto alla nostra Terra e che NON assomiglierà MAI alla nostra Terra.
Pensate: se la regola fondamentale della “Vita”, nel suo senso più ampio e profondo, è esprimibile nel concetto di “ADATTAMENTO NEL TEMPO”, allora è ragionevole pensare che su Titano, in fondo (e riflettendoci bene), potrebbero essere in corso da ere ed ere (!) processi tali da aver consentito la nascita e lo sviluppo di Forme di Vita indigene assolutamente peculiari, per noi inimmaginabili e, per ovvi motivi, completamente diverse da quelle che caratterizzano la Terra e gli ipotetici ambienti alieni di tipo simil-terrestre.
Il fatto che la ricerca (talvolta esasperata) di similitudini fra altri mondi ed il “nostro” mondo costituisca una caratteristica peculiare e propria della Scienza (Astronomica e non solo) Moderna e dell’atteggiamento degli scienziati che la praticano è indubitabile; ma che un simile approccio, alla fine, non possa venirsi a caratterizzare se non per la sua intrinseca limitatezza (e per lo strabismo scientifico che geneticamente lo affligge), ci sembra un elemento sul quale si dovrebbe riflettere meglio e maggiormente.
MareKromium
(4 voti)
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Titan-Surface-37.gifOn the way down... - Sol 1 (GIF-Movie; credits: Dr G. Barca)58 visiteLa consistenza apparente (e cioè sulla base dell’osservazione visuale diretta) del suolo di Titano suggerisce quella della sabbia umida e ciò ha fatto pensare che il terreno su cui si è poggiata la Huygens Probe possa essere periodicamente (rectius: frequentemente) soggetto al passaggio di liquidi.
Ad onor del vero, le immagini della superficie di Titano ottenute da Huygens – certo suggestive, ma poche e di mediocre qualità – non ci sono state di grande aiuto per comprendere in maniera adeguata la realtà superficiale di Titano e quindi, per fornire al Lettore un’idea di quello che un ipotetico astronauta potrebbe realmente vedere in seguito ad un Landing sulla “Luna Nebbiosa”, abbiamo dovuto fare ricorso ad una serie di riflessioni e speculazioni.
MareKromium
(4 voti)
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Titan-Surface-35.gifOn the Surface... - Sol 1 (GIF-Movie; credits: Dr G. Barca)59 visiteNel Gennaio 2005, come molti sanno, venne compiuto un primo e storico passo verso l’esplorazione “profonda” di Titano: dalla Sonda-madre Cassini, infatti, fu sganciato il modulo Huygens il quale, agendo su sola base inerziale (e cioè procedendo nello spazio senza l’ausilio di propulsori), arrivò a “tuffarsi” nella gelida atmosfera di Titano (il giorno 14 gennaio 2005) e poi, dopo una lunga discesa attraverso le sue nebbie arancio-marroni (una discesa durata qualcosa come 2 ore e 27 minuti!), ne raggiunse felicemente la superficie.
Da lì, poi, questa piccola probe avrebbe trasmesso dati (ufficialmente) per circa un’ora e mezza.
Il Modulo Remoto Huygens, al contrario di quanto temuto da molti scienziati, è riuscito ad evitare il landing su una superficie liquida e, dopo aver visto, fotografato e “sfiorato” una fitta rete di canali e di altri rilievi superficiali scuri e non identificabili con certezza (forse dei laghetti), si è delicatamente posato su quello che sembra essere il greto asciutto di un torrente.
Rocce e cristalli che mostrano chiari segni di erosione da fluidi sono ben visibili tutto intorno alla Sonda e poi, scrutando l’orizzonte più lontano, il profilo scuro ed ovattato di rilievi distanti qualche centinaio di metri sembra affacciarsi alla vista.
MareKromium
(4 voti)
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Titan-Shoreline_and_Drainage_Channels-02b.jpgShoreline and Drainage Channels' Network on Titan (possible True Colors; credits: Lunar Explorer Italia)66 visiteDa un frame "Huygens", la ricostruzione in possibili Colori Veri (ma con saturazione leggermente aumentata, per favorire la visibilità dei dettagli) del panorama che un ipotetico Astronauta, in discesa verso "la Luna Nebbiosa", si troverebbe davanti agli occhi.MareKromium
(4 voti)
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Titan-W00051725.jpgCrescent Titan (possible True Colors; credits: Lunar Explorer Italia)58 visiteCrescent Titan (possible True Colors; credits: Lunar Explorer Italia)
Caption NASA:"W00051725.jpg was taken on December 05, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approx. 147.760 Km away.
The image was taken using the CB3 and CL2 filters".
MareKromium
(4 voti)
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Titan-N00124860.jpgTitan in possible True Colors (credits by Lunar Explorer Italia)58 visiteCaption NASA:"N00124860.jpg was taken on December 05, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approximately 176.792 Km away.
The image was taken using the CL1 and CB3 filters". MareKromium
(4 voti)
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Titan-N00124864.jpgTitan in possible True Colors (credits by Lunar Explorer Italia)58 visiteCaption NASA:"N00124864.jpg was taken on December 05, 2008 and received on Earth December 06, 2008. The camera was pointing toward TITAN that, at the time, was approximately 171.534 Km away.
The image was taken using the CL1 and CB3 filters".MareKromium
(4 voti)
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Titan-PIA10514.jpgThe "Foggy" Moon (IR Light - possible True Colors; credits: Lunexit)83 visiteCaption NASA:"The Cassini Spacecraft looks through Titan's thick atmosphere to reveal bright and dark terrains on the Saturn-facing Side of the Planet's largest moon. North is up.
The image was taken with the Cassini Spacecraft narrow-angle camera on Oct. 11, 2008 using a spectral filter sensitive to wavelengths of IR Light centered at 938 nanometers. The view was obtained at a distance of approx. 2,2 MKM (about 1,3 MMs) from Titan and at a Sun-Titan-Spacecraft, or Phase, Angle of 10°.
Image scale is roughly 13 Km (about 8 miles) per pixel".MareKromium
(4 voti)
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Titan-Clouds-North_Polar_Clouds-PIA10511.jpgBright Northern Clouds on Titan (natural colors; credits: Lunexit)103 visiteCaption NASA:"Bright clouds circumscribe Titan's North Polar Region: a frigid land of Methane Seas.
The clouds seen in this image and other recent Cassini Spacecraft views are at higher latitudes than similar streak-like clouds observed in the Southern Hemisphere (see PIA08966). Scientists are working to understand why such clouds appear preferentially at certain latitudes on Saturn's largest moon.
While the streaks that grace Titan's Southern Hemisphere are often seen at 40° South Latitude, similar to Wellington, New Zealand, the streaks in the Northern Hemisphere are farther from the Equator, near 56° North Latitude, which is similar to Glasgow, Scotland. North on Titan is up and rotated 16° to the right.
The image was taken with the Cassini spacecraft narrow-angle camera on Sept. 30, 2008 using a spectral filter sensitive to wavelengths of infrared light centered at 938 nanometers. The view was obtained at a distance of approx. 1,2 MKM (such as about (776.000 miles) from Titan and at a Sun-Titan-Spacecraft, or Phase, angle of 71°.
Image scale is 7 Km (about 4,5 miles) per pixel".MareKromium
(4 voti)
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Titan-Channels-Unnamed_Channels-PIA10956.jpgXanadu's Channels (false colors; credits: Lunexit)58 visiteOn the final flyby of Cassini's original 4-year tour, its radar mapper captured these unusual channels on Titan at the edge of Xanadu, the widest seen in this area (For a radar image of Xanadu, see PIA08428). These might be active rivers carrying methane or debris, or they might be dry riverbeds similar to earthly "arroyos".
Past Cassini radar images have revealed different types of channels on Titan's surface (see PIA03565 and PIA07366). They vary from bright to dark in radar (rough to smooth), and from fan-shaped to braided to meandering.
Some, drain into lakes; others disappear. Some of these channels may be several hundred meters, or feet, deep.
This image, taken from the flyby on May 28, 2008, shows the border of Xanadu as the bright-dark boundary running from the upper left to lower right. Southward from that boundary is an unusual set of channels. While these are brighter (more roughly textured) than the surrounding terrain, some are only slightly brighter, and some are as wide as 5 Km (about 3 miles) — about the size of the River Thames at its mouth east of London.
They appear to flow out of the rough Region of Xanadu.
Careful inspection reveals smaller tributaries that wind through the brighter and apparently rougher terrain to the north. A close-up of one of the widest channels is shown at the lower left.
Scientists think that many of the channels on Titan are carved by methane deposited on the surface from strong but infrequent rainstorms. A bright channel may be dry, with the rough riverbed of icy particles (like those seen at the Huygens Landing Site) producing the radar brightness. The darker channels in this image resemble the dry lakes seen in the North Polar area of Titan, so they may be dry as well, with their smoother (radar-dark) surfaces caused by finer-grained sediment deposits on the channel floors.
This image shows an area located at 15° South Latitude and 121° West Longitude. It is about 450 Km (about 280 miles) across, and has approximately 1 Km (0,62-mile) resolution.
North is up.MareKromium
(4 voti)
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Titan-Craters-Unnamed_Craters-PIA10655.jpgTitanian Craters (Impact Craters?) - radio-image; credits: NASA59 visiteCaption NASA:"This side-by-side view shows a newly discovered impact crater (at left) compared with a previously discovered crater (at right). The new crater was just discovered by the Cassini Spacecraft's Radar Instrument during its most recent Titan flyby on May 12, 2008. This makes the fourth feature definitely identified as an impact crater so far on Titan -- fewer than 100 features are regarded as possible impacts. Compared with Saturn's other moons, which have many thousands of craters, Titan's surface is very sparsely cratered. This is in part due to Titan's dense atmosphere, which burns up the smaller impacting bodies before they can hit the surface. Geological processes, such as wind-driven motion of sand and icy volcanism, may also wipe out craters.
Both images are about 350 Km (approx. 217 miles) in width.
The crater on the right was discovered by Cassini in 2005 and is shown here for comparison. It is about 80 Km (approx. 50 miles) in diameter, with the radar illumination from above.
Called "Sinlap", this crater is estimated to be about 1300 meters (984 feet) deep.
The new feature pictured on the left, which has not been named yet, is bigger than the Sinlap Crater with a diameter of about 112 Km (approx. 70 miles).
The new crater is located at about 26° North Latitude and 200° West Longitude, in the bright Region known as Dilmun, about 1000 Km (approx. 600 miles) north of the Huygens Landing Site.
In its image, also illuminated from above, it appears slightly irregular, suggesting that it was modified after it was formed, perhaps by collapses of segments of its rim onto the floor.
The crater floor appears flat, and two small bright spots indicate a likely central peak complex.
The ejecta blanket (surrounding material) from this crater is less prominent than that of the Sinlap Crater.
The crater's more degraded character suggests it could be older than Sinlap (assuming that erosive processes are the same at both locations, which are at similar latitudes)".MareKromium
(4 voti)
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Titan-PIA08391.jpgHiding behind the Rings60 visiteCassini delivers this stunning vista showing small, battered Epimetheus and smog-enshrouded Titan, with Saturn's A and F-Rings stretching across the scene.
The color information in the colorized view is completely artificial: it is derived from red, green and blue images taken at nearly the same time and phase angle as the clear filter image. This color information was overlaid onto the previously released clear filter view in order to approximate the scene as it might appear to human eyes.
The prominent dark region visible in the A-Ring is the Encke Gap (about 325 Km, or 200 miles wide), in which the moon Pan and several narrow ringlets reside. Moon-driven features which score the A-Ring can easily be seen to the left and right of the Encke Gap.
A couple of bright clumps can be seen in the F-Ring.
Epimetheus is 116 Km (72 miles) across and giant Titan is 5.150 kilometers (3.200 miles) across.
The view was acquired with the Cassini spacecraft narrow-angle camera on April 28, 2006, at a distance of approx. 667.000 Km (about 415.000 miles) from Epimetheus and 1,8 MKM (about 1,1 MMs) from Titan. The image captures the illuminated side of the Rings. The image scale is roughly 4 Km (about 2 miles) per pixel on Epimetheus and about 11 Km (approx. 7 miles) per pixel on Titan.MareKromium
(4 voti)
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