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Tempel1-PIA07881.jpgTempel-1, from Kitt Peak (pseudo-colors)59 visiteCaption NASA originale:"The Kitt Peak National Observatory's 2,1-meter telescope observed comet Tempel 1 on April 11, 2005, when the comet was near its closest approach to the Earth. A pinkish dust jet is visible to the SouthWest, with the broader neutral gas coma surrounding it. North is up, East is to the left and the field of view is about 80.000 Km wide. The Sun was almost directly behind the observer at this time. The red, green and blue bars in the background are stars that moved between the individual images.
This pseudo-color picture was created by combining three black and white images obtained with different filters. The images were obtained with the HB Narrowband Comet Filters, using CN (3870 A - shown in blue), C2 (5140 A - shown in green) and RC (7128 A - shown in red).
The CN and C2 filters capture different gas species (along with the underlying dust) while the RC filter captures just the dust".
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Tempel1-S-ImpactConfirmation.jpgTempel-1 from Kitt Peak National Obs.56 visiteOriginal caption:"The image was taken through an R band filter and has the smoothed dust light profile removed to enhance the jets. North is up, East to the left, the Sun at PA (Position Angle) 290 and the FOV is 2,5 arcmin (which is now 96.500 km at the comet)".
T. Farnham and Jianyang Li
(University of Maryland)
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Tempel1-U-HST.jpgDeep-impact from HST55 visiteCaption NASA originale:"These 2 pictures of comet Tempel-1 were taken by NASA's HST. They show the comet before and after it ran over NASA's Deep Impact probe".
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Tempel1-VV-nhvcaxf9000910-PIA02131.jpgImpact Time!58 visiteWhen NASA's Deep Impact probe collided with Tempel-1, a bright, small flash was created, which rapidly expanded above the surface of the comet. This flash lasted for more than a second and its overall brightness is close to that predicted by several models. After the initial flash, there was a pause before a bright plume quickly extended above the comet surface. The debris from the impact eventually cast a long shadow across the surface, indicating a narrow plume of ejected material, rather than a wide cone. The Deep Impact probe appears to have struck deep, before gases were heated and explosively released. The impact crater was observed to grow in size over time. A preliminary interpretation of these data indicate that the upper surface of the comet may be fluffy, or highly porous. The observed sequence of impact events is similar to laboratory experiments using highly porous targets, especially those that are rich in volatile substances. The duration of the hot, luminous gas phase, as well as the continued growth of the crater over time, all point to a model consistent with a large crater.
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Tempel1-W.jpgDeep-impact...13 seconds after collision!56 visiteCaption NASA originale:"This image shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel-1 at 10:52 p.m. Pacific Time, July 3 (1:52 a.m. Eastern time, July 4). It was taken by the spacecraft's high-resolution camera 13 seconds after impact. The image has been digitally processed to better show the comet's nucleus".
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Tempel1-X.jpgDeep-impact...16 seconds after collision!56 visiteCaption NASA originale:"This image shows the initial ejecta that resulted when NASA's Deep Impact probe collided with comet Tempel-1 at 10:52 p.m. Pacific time, July 3 (1:52 a.m. Eastern time, July 4) . It was taken by the spacecraft's medium-resolution camera 16 seconds after impact".
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Tempel1-XX-HRI_937_1.jpgDeep-impact...67 seconds after collision!56 visitecaption NASA originale:"This spectacular image of comet Tempel 1 was taken 67 seconds after it obliterated Deep Impact's impactor spacecraft. The image was taken by the HR camera on the mission's flyby craft. Scattered light from the collision saturated the camera's detector, creating the bright splash seen here. Linear spokes of light radiate away from the impact site, while reflected sunlight illuminates most of the comet surface. The image reveals topographic features, including ridges, scalloped edges and possibly impact craters formed long ago".
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Tempel1-XXX-streakoflight.jpgSpace Fireworks...56 visiteCaption NASA originale:"...In the almost 2 hours of time that elapsed during the imaging of the comet, its position changed against the background stars. When all of the images of the motion are added together, the resulting streak of light is shown in the image above. Starting from the left, the comet was its natural brightness. The streak brightens significantly in the middle, immediately after impact of the probe".
Nota: i primi resoconti sui risultati scientifici dell'esperimento ci dicono che la NASA ha "scoperto" che sulla superficie della cometa Tempel-1 c'era (c'è) uno strato di polvere simile al borotalco, ergo più sottile di quanto ci si aspettasse. Inutile dire che, se messo in questi termini, il significato dell'esperimento va ad esaurirsi in un qualcosa che fa solo sorridere (di imbarazzo).
La realtà è molto più complessa e coinvolge la natura, la struttura e la composizione dei cd. "corpi cometari" in rapporto agli altri "corpi rocciosi" presenti nel Sistema Solare...
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Tempel1-XXXX-ITS_PressRelease2.jpgThe nucleus of comet Tempel-156 visite...e su questi aspetti (critici) dell'esperimento, non abbiamo ancora dati da presentare e commentare.
Dati che, a quanto dice il Prof. R. Hoagland, non verranno MAI (?) resi noti.
Vi suggeriamo, a tal proposito, di leggere il suo nuovo (discutibile, ma comunque interessante) editoriale, pubblicato sul Sito "The Enterprise Mission" e dal titolo "Captain's Blog - Space News & General Commentary by Richard C. Hoagland".
Nota: questa bella immagine del nucleo della cometa è stata ottenuta dai sensori di puntamento dell'Impactor, circa 5 minuti prima dell'urto.
L'impatto, a titolo di curiosità, è avvenuto fra i due piccoli crateri dal bordo scuro che possiamo vedere in basso, quasi a ridosso del margine inferiore del nucleo stesso (o del Polo Sud, se preferite).
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Tempel1-Y.jpgThe South-Pole of Tempel-1 and the impact area56 visiteDa "NASA - Picture of the Day" del 6 Luglio 2005:"This diverse landscape is the surface of comet Temple-1's nucleus as seen by the Deep Impact probe's Impactor Targeting Sensor. Within minutes of recording the rugged view, the landscape had changed dramatically though, as the impactor smashed into the surface near the two large, half kilometer-sized craters at picture center. Indications are that the probe penetrated well below the surface before vaporizing, sending a relatively narrow plume of debris blasting back into space. Researchers are still speculating on the final size of the crater produced by the July 4th comet crash, but material continues to spew from the impact site and has caused the faint comet to brighten significantly. Determining the crater dimensions and analyzing the debris ejected from the comet's interior will provide premier insights into the formation of comet Tempel 1, a primordial chunk of our own Solar System".
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Tempel1-Z-HST-1-061405.jpgDeep Impact from HST57 visiteLa NASA - anzi: l'attuale Amministrazione USA - dunque, ce l'ha fatta: per festeggiare il 4 di Luglio, dato che la siccità domina in quasi tutti gli Stati Uniti ed i "fireworks" sono stati vietati, i fuochi artificiali si è pensato bene di andare a farli nello Spazio. Abbiamo letto i commenti della Dott.ssa M. Hack su questo evento e, sebbene le sue motivazioni sul fatto che sia stata una cattiva idea sono diverse dalle nostre, per stavolta ci troviamo in sostanziale sintonia con quanto espresso da questo 'Monumento Vivente' della divulgazione scientifica in Italia. Però il punto nodale di tutta le questione è, a nostro parere, un altro: quando la Francia, in passato, ha utilizzato Mururoa come poligono nucleare, il Mondo si è indignato, ma l'esperimento è stato eseguito lo stesso. Ora sembra che qualcuno abbia deciso di inziare a fare esperimenti 'sparando addosso' a corpi celesti ed il fatto che non sia stata usata (ancora...) una testata nucleare, secondo noi, non rende il fatto meno grave.
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Tempel1-Z-I-HST.jpgThe impact sequence from HST63 visiteDa "NASA - Picture of the Day", del giorno 18 Luglio 2005:"It was a human-made event visible across the Solar System. At the direction of terrestrial scientists, a refrigerator-sized probe from the Deep Impact mission struck Comet Tempel-1 on July 4 at over 35.000 Km per hour.
The unexpectedly bright explosion was not nuclear but rather originated from a large plume that reflected back sunlight. Pictured above is how the event looked to the Earth-orbiting HST. A large cloud of bright material is seen emanating from the comet's nucleus and then dispersing. The area encompassing the comet became over two times brighter in the hours after the impact. Astronomers will continue to study the images and data returned by Deep Impact to better determine the nature of Comet Tempel-1 and discern clues about the formation dynamics of the early Solar System".
Nota: leggendo questa poche righe non serve uno Scienziato per capire che, al momento, l'unico scopo chiaro dell'esperimento era quello di fare propaganda...
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