| Ultimi arrivi - Asteroids and Comets |
Eros from 700 mt - PIA03146_modest.jpgFalling down: Eros from 700 mt57 visiteCaption NASA:"...The image is 33 meters across. The large, oblong rock casting a big shadow measures 7.4 meters across...".
Riuscite a distinguere in questo scorcio ulteriormente ravvicinato qualche dettaglio il quale - ora, ovviamente, ingrandito - fosse già presente nel frame precedente? Noi non ci siamo riusciti.Ott 28, 2004
|
|
Eros from 1150 mt - PIA03145_modest.jpgFalling down: Eros from 1150 mt58 visiteIn sequenza, le ultime (?) 4 immagini ricevute sulla Terra e relative alla discesa della Sonda NEAR sull'asteroide Eros. Purtroppo non siamo in grado di operare delle valutazioni precise sul contenuto di questi frames i quali, per svariati ordini di motivi, NON ci convincono. I particolari della superficie di Eros variano da frame a frame (come se la Sonda stesse precipitando, seguendo una traiettoria non lineare), ma la qualità (in termini di definizione e nitidezza dei dettagli ripresi) dei singoli frames, invece, lascia supporre un landing morbido ed una discesa "smooth".
La NASA, inoltre, dice che "...The image is 54 meters across. The large rock at lower left is 7.4 meters across..." ma questi dati non sembrano totalmente convincenti.
Vediamo gli altri 3 frames...Ott 28, 2004
|
|
Eros - impact site - PIA03144_modest.jpgEros: NEAR-Shoemaker's Probe landing site57 visiteThis map projection of NEAR Shoemaker images shows locations and sizes of landmarks surrounding the spacecraft's planned landing site. Diameters of craters are shown in red, and diameters of boulders are shown in yellow. Diameters are given in units of meters (1 meter is about 3.3 feet). Coordinates along the left side of the map are degrees south latitude and coordinates along the bottom are degrees west longitude.
The six yellow "footprint" boxes represent approximate image size at 500, 1.000, 1.500, 2.000, 2.500 and 3.000 meters above the surface during descent. The spacecraft will take pictures continuously between each spot. The arrow marks the estimated touchdown site.Ott 28, 2004
|
|
Comets-Borrelly_Comet-PIA03500_modest.jpgThe "Borrelly" Comet from Deep Space 158 visiteIn this highest resolution view of the icy, rocky nucleus of comet Borrelly, (about 45 meters or 150 feet per pixel) a variety of terrains and surface textures, mountains and fault structures, and darkened material are visible over the nucleus's surface. This was the final image of the nucleus of comet Borrelly, taken just 160 seconds before Deep Space1's closest approach to it. This image shows the 8-km (5-mile) long nucleus about 3417 kilometers (over 2,000 miles) away.
Smooth, rolling plains containing brighter regions are present in the middle of the nucleus and seem to be the source of dust jets seen in the coma. The rugged land found at both ends of the nucleus has many high ridges along the jagged line between day and night on the comet. This rough terrain contains very dark patches that appear to be elevated compared to surrounding areas. In some places the dark material accentuates grooves and apparent faults.Ott 28, 2004
|
|
Asteroids-Annefrank_Asteroid-PIA02885_modest.jpgAsteroid Annefrank from Stardust67 visiteAsteroid Annefrank is seen as irregularly shaped, cratered body in an image taken by NASA's Stardust spacecraft during a Nov. 2 flyby of the asteroid.
Stardust flew within about 3.300 Km (about 2.050 miles) of the asteroid as a rehearsal for the spacecraft's encounter with its primary target, comet Wild 2, in January 2004. The camera's resolution was sufficient to show that Annefrank is about 8 Km (5 miles) in length, twice the predicted size from Earth-based observations. The surface reflects about 0,1 to 0,2% of sunlight, slightly less than anticipated. A few craters that are hundreds of meters across can be seen. The straight edge in the right side of the image may be an artifact of processing.Ott 28, 2004
|
|
EROS-PIA03143.jpgEros: NEAR-Shoemaker's Probe landing site81 visiteThe location of NEAR Shoemaker's landing site is shown in this image mosaic taken on December 3, 2000, from an orbital altitude of about 200 Km (approx. 124 miles). In this view, south is to the top and the terminator (the imaginary line dividing day from night) lies near the equator. The landing site (at the tip of the arrow) is near the boundary of two distinctly different provinces, both of which the spacecraft will photograph as it descends. To the south and east (above and to the left) lies older, cratered terrain, while to the north (down) is the saddle-shaped feature Himeros, whose lesser density of superposed craters indicates relatively recent resurfacing by geologic processes.Ott 17, 2004
|
|
EROS-PIA02951.jpgEros from above (1)64 visiteIn NEAR Shoemaker's long-awaited close-up images of Eros, the asteroid's small-scale features are revealing their fascinating diversity. This picture, taken July 8, 2000, from an orbital altitude of only 36 Km, shows a variety of differently shaped boulders. Some are nearly round, whereas others are elongated or even blade-shaped. Such varied shapes might arise from differences in the strength and fracturing of preexisting rock. The whole scene is about 1.4 Km across.Ott 16, 2004
|
|
IDA-PIA00138.jpgAsteroid Ida's limb (HR)68 visiteThe Galileo imaging system captured this picture of the limb of the asteroid 243 Ida about 46 seconds after its closest approach on August 28, 1993, from a range of only 2480 Km. It is the highest-resolution image of an asteroid's surface ever captured and shows detail at a scale of about 25 meters per pixel. This image is one frame of a mosaic of 15 frames shuttered near Galileo's closest approach to Ida. Since the exact location of Ida in space was not well-known prior to the Galileo flyby, this mosaic was estimated to have only about a 50 percent chance of capturing Ida. Fortunately, this single frame did successfully image a part of the sunlit side of Ida. The area seen in this frame shows some of the same territory seen in a slightly lower resolution full disk mosaic of Ida returned from the spacecraft in September, 1993, but from a different perspective. Prominent in this view is a 2 Km deep "valley" seen in profile on the limb.Ott 16, 2004
|
|
IDA-PIA00135.jpgAsteroid Ida (HR)59 visiteThis view of the asteroid 243 Ida is a mosaic of 5 image frames acquired by the Galileo spacecraft's solid-state imaging system at ranges of 3.057 to 3.821 Km on August 28, 1993, about 3-1/2 minutes before the spacecraft made its closest approach to the asteroid. Galileo flew about 2.400 Km from Ida at a relative velocity of 12.4 km/sec (28,000 mph). Asteroid and spacecraft were 441 million Km from the Sun. Ida is the second asteroid ever encountered by a spacecraft. It appears to be about 52 Km in length, more than twice as large as Gaspra, the first asteroid observed by Galileo in October 1991. Ida is an irregularly shaped asteroid placed by scientists in the S class (believed to be like stony or stony iron meteorites). It is a member of the Koronis family, presumed fragments left from the breakup of a precursor asteroid in a catastrophic collision. This view shows numerous craters, including many degraded craters larger than any seen on Gaspra.Ott 16, 2004
|
|
IDA&DACTYL-PIA00333.jpgIda and Dactyl in "natural colors"69 visiteThis color picture is made from images taken by the imaging system on the Galileo spacecraft about 14 minutes before its closest approach to asteroid 243 Ida on August 28, 1993. The range from the spacecraft was about 10,500 kilometers (6,500 miles). The images used are from the sequence in which Ida's moon was originally discovered; the moon is visible to the right of the asteroid. This picture is made from images through the 4100-angstrom (violet), 7560 A (infrared) and 9680 A (infrared) filters. The color is 'enhanced' in the sense that the CCD camera is sensitive to near infrared wavelengths of light beyond human vision; a 'natural' color picture of this asteroid would appear mostly gray. Shadings in the image indicate changes in illumination angle on the many steep slopes of this irregular body as well as subtle color variations due to differences in the physical state and composition of the soil (regolith). Ott 16, 2004
|
|
GASPRA-PIA00119.jpgAsteroid Gaspra74 visiteThis picture of asteroid 951 Gaspra is a mosaic of 2 images taken by the Galileo spacecraft from a range of 5.300 Km, some 10 minutes before closest approach on October 29, 1991. The Sun is shining from the right; phase angle is 50 degrees. The resolution, about 54 meters/pixel, is the highest for the Gaspra encounter and is about three times better than that in the view released in November 1991. Additional images of Gaspra remain stored on Galileo's tape recorder, awaiting playback in November. Gaspra is an irregular body with dimensions about 19 x 12 x 11 Km. The portion illuminated in this view is about 18 Km from lower left to upper right. The north pole is located at upper left; Gaspra rotates counterclockwise every 7 hours. The large concavity on the lower right limb is about 6 Km across, the prominent crater on the terminator, center left, about 1.5 Km. A striking feature of Gaspra's surface is the abundance of small craters. More than 600 craters, 100-500 meters (330-1650 feet) in diameter are visible here. The number of such small craters compared to larger ones is much greater for Gaspra than for previously studied bodies of comparable size such as the satellites of Mars.Ott 16, 2004
|
|
EROS-PIA03129.jpgEros from above (2)66 visiteNEAR Shoemaker photographed this area of Eros on December 18, 2000, from an orbital altitude of 33 Km. This part of the asteroid's surface, like many others, appears vaguely "sculptured" due to its low, elongated ridges and depressions with seemingly consistent orientations. Some of the low spots also contain accumulations of smooth, pond-like materials. Neither the surface sculpturing nor the pond-like materials are well understood, and both will be investigated in detail using even higher-resolution images from NEAR Shoemaker's low passes over Eros in early 2001. The whole scene is about 1 Km across.Ott 16, 2004
|
|
| 282 immagini su 24 pagina(e) |
 |
|
|
|
|
|
|
|
|
23 |
|
