| Piú viste - 433-Eros: Pictures, Facts and Legends |
19981223.jpgViews of 433-Eros55 visiteThis montage of images of the asteroid Eros was assembled from images acquired by the Near Earth Asteroid Rendezvous (NEAR) Spacecraft on December 23, 1998, as the Spacecraft flew by the asteroid at a distance of 2300 miles (3800 Km) at 1:43 PM EST. Shown are nine early views out of 29 that were obtained during the flyby. These images were taken between 10:44 AM and 12:44 PM EST, as the Spacecraft range closed from 7300 miles (such as abou 11.100) Km, to 3300 miles (such as approx. 5300 Km).
During that time, the Asteroid completed nearly half of a rotation. The smallest resolved detail is approximately 1650 feet (500 meters) across.
A firing of the main engine at 17:00, EST, on December 20, 1998, designed to slow the Spacecraft for insertion into orbit around the Asteroid, was aborted by the Spacecraft. Contact with ground controllers was temporarily lost, but was regained at 20:00 EST on December 21, when autonomous Spacecraft safety protocols took over and transmitted a signal to the ground. All spacecraft systems were determined to be healthy and operational.
Within hours, a flyby observation sequence was developed and uploaded to the Spacecraft.
1026 images were acquired by the Multispectral Imager, to determine the size, shape, morphology, rotational state, and color properties of Eros, and to search for small moons.
The Infrared Spectrometer measured spectral properties of the Asteroid to determine what minerals were present, and the Magnetometer searched for a natural Magnetic Field.
Analysis of the Spacecraft radio signal were also used to determine the asteroid's mass and density.
The main engine was fired successfully on January 3, 1999, placing NEAR on-course for a February 2000 rendezvous.
Eros is NEAR's second asteroid encountered. On June 27, 1997, NEAR flew by the Main-Belt Asteroid Mathilde at a range of approx. 1212 Km (750 miles).MareKromium
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20000225.jpgThe "Two Faces" of Eros... (natural colors; credits: Lunexit)55 visiteOn February 23, 2000, the NEAR spacecraft obtained a sequence of image mosaics showing Eros' surface as the asteroid rotated under the Spacecraft. At that time the range to the surface was approx. 355 Km (about 220 miles). These two mosaics, part of that sequence, show the stark beauty of the two opposite hemispheres.
The smallest detail visible is 35 meters (120 feet) across. The top mosaic shows wavy brightness banding exposed in the interior walls of the Saddle. In the bottom mosaic, similar banding is visible in one of the craters near the limb at left. To the right, the angle of the illumination accentuates the quasi-linear troughs near the Terminator.
Successful firing of NEAR's thrusters yesterday, February 24, placed the Spacecraft on course for insertion into the next lower orbit, at a 200 Km (about 120 miles) altitude. Images from that orbit, commencing in early March, will have nearly twice the spatial resolution of data returned so far.
(Product compiled from images 0126712790, 0126713054, 0126713230, 0126723526, 0126723790, 0126723878)
MareKromium
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N-M0135269508F4.pngRocky Outcrop on 433-Eros (3D - credits: Dr G. Barca - Lunexit Team)55 visitenessun commentoMareKromium
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20000214g.jpgNEAR's historic first image from Eros orbit (natural colors; credits: Lunexit)54 visiteOn February 14, 2000, at 10:33 AM EST the NEAR Spacecraft was successfully inserted into orbit around 433 Eros, becoming the first artificial satellite of an asteroid. Just over an hour later, NEAR pointed its camera at the asteroid and took this picture from a range of 210 miles (330 km) above the surface.
Mission navigators and operators will use this image and others to be taken later to traingulate on landmarks on the asteroid's surface, precisely measuring position of the spacecraft to plot NEAR's course.
Features as small as a 100 feet (30 meters) across can be seen. This view shows the 3-mile (5-Km) impact crater which the Spacecraft has spied for over a week during its approach. The two smaller craters superimposed on its rim are each about 1,2 miles (approx. 2 Km) across. An enormous boulder a full 170 feet (50 meters) in size sits on the large crater's floor. Other key features of the surface are shallow subsurface layering exposed near the tops of crater walls, and shallow grooves crossing the surface and cutting the crater's rim.
(Mosaic of images 0125957025 and 0125957087)MareKromium
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20000301.jpgThe "Profile" of 433-Eros (natural colors; credits: Lunexit)54 visiteNEAR takes several images mosaics of 433-Eros daily for purposes of navigating the Spacecraft. The one shown here was taken February 29, 2000, from a range of 289 Km (about 180 miles).
It shows features as small as 30 meters (100 feet) across. All of the mosaics show the same territory over and over, but changes in lighting plus the gradual decrease in the spacecraft's range to the surface are both constantly bringing out new details.
The very oblique illumination in this mosaic is ideal for bringing out small landforms. Many parts of the asteroid have "grooves", such as linear troughs about 100 meters (330 feet) wide and several kilometers long. Similar features have also been observed on other asteroids such as Gaspra, and they are especially numerous on Mars' moon Phobos.
Their origin isn't completely understood, but formation of the grooves probably involves fracturing of the asteroid's subsurface in some way.
(Mosaic of images 0127210446, 0127210510, 0127210574, 0127210656)MareKromium
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20000222.jpg54 visiteThis image mosaic of Eros was taken by the NEAR Spacecraft on Feb. 18, 2000 from a range of 224 miles (about 361 Km). The smallest detail visible on the surface is about 115 feet (35 meters) across.
At the time the Spacecraft was over the shadowed Southern Hemisphere, looking North at a crescent Eros.
Although this view of Eros is similar to others that have been returned, the coverage at different illumination and viewing geometries provides important information on the shapes of landforms.
(Mosaic of images 0126286145, 0126286419, 0126286483)MareKromium
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20000309.jpgOblique view of the "Large Crater" (natural colors; credits: Lunexit)54 visiteThis image, showing an oblique view of Eros' "Large (central) Crater", was taken at a resolution of about 20 meters (65 feet) per pixel. The brightness or albedo patterns on the walls of this crater are clearly visible, with the brighter materials near the tops of the walls and darker materials on the lower walls. Boulders are seen inside this crater and the smaller nearby craters. The higher density of craters to the left of the large crater implies that this region is older than the smoother area seen associated with the Saddle Region on the opposite side of the asteroid.
(Image 0127591846)MareKromium
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20000418.jpgUp-close and personal (natural colors; credits: Lunexit)54 visiteSince April 11, 2000, the NEAR Shoemaker Spacecraft has orbited Eros at an altitude of about 100 Km (approx. 62 miles) from the Asteroid's Center. Images acquired from this orbit will be used to make a HR map of the illuminated portion of the Asteroid. Each spot on the surface will be imaged under a variety of lighting and viewing conditions to bring out different features.
In this image, taken April 17, 2000, from a height of 101 Km (approx. 63 miles), the shadows highlight small-scale surface features. The surface is pockmarked with craters ranging in size up to the 2,8-Km (1,74-mile) diameter crater in the center of the image. The smallest craters which can be resolved are about 20 meters (65 feet) across.
In lower right corner of the image, 20-meter boulders can be seen that were not evident in images from higher altitudes.
(Image 0131288775)MareKromium
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M0132557824F4-pseudoparabola.pngThe "Pseudo-Dish" is gone...54 visiteUn nuovo "tassello", nella Saga delle Leggende di 433-Eros: la "Parabola".
In questo frame, che riprende il nostro "oggetto misterioso" da un angolo visuale opposto rispetto a quello solito (e cioè l'angolo visto e stravisto nelle immagini che popolano Internet), anche l'Osservatore più sbadato potrà vedere e verificare che il rilievo che, per alcuni Appassionati di Anomaly Hunting, sembrava e/o assomigliava e/o era un oggetto discoidale (una sorta di "Parabola per la Trasmissione e/o la Ricezione di Segnali", si è detto e scritto), è in realtà un boulder vagamente rettangolare, che accede ad un outcrop di modeste dimensioni.
Maggiori dettagli ed informazioni al riguardo seguiranno nell'articolo che chiuderà la "Trilogia di 433-Eros", di prossima pubblicazione su TruePlanets.
Per Vostra opportuna informazione, il "Rilievo Controverso" (chiamiamolo in questo modo "neutro", così non facciamo torto a nessuno) si trova alle seguenti coordinate: 14,46° Latitudine Nord e 256,77° Longitudine Est). MareKromium
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