| Piú viste - Venus |
Venus-PIA10124-PCF-LXTT-IPF.jpgApproaching Venus (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)78 visiteCaption NASA:"The Planet Venus is enshrouded by a Global Layer of Clouds that obscures its surface to the MESSENGER Dual Imaging System (MDIS) cameras. This single frame is part of a color sequence taken to help the MESSENGER team calibrate the camera in preparation for the spacecraft's first flyby of Mercury on January 14, 2008. Over the next several months the camera team will pore over the 614 images taken during this Venus encounter to ascertain color sensitivity and other optical properties of the instrument. These tasks address two key goals for the camera at Mercury: understanding surface color variations and their relation to compositional variations in the Crust, and ensuring accurate cartographic placement of features on Mercury's Surface.
Preliminary analysis of the Venus Fly-By images indicates that the cameras are healthy and will be ready for next January's close encounter with Mercury".
Nota Lunexit: questo NASA - MESSENGER color-frame stato prima riportato sulla Scala dei Grigi, poi ingrandito, riprocessato e poi ricolorizzato in Colori Naturali Assoluti. Il risultato un p bizzarro, probabilmente poco realistico, ma sen'altro suggestivo. Giudicate Voi!MareKromium
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8-Venus_from_Venus_Express-VIRTIS_COB05_vis_397_b.jpgVenus, from Venus Express (natural colors)77 visiteCaption ESA originale:"Views of the Southern Hemisphere of Venus in visible and ultraviolet light show interesting atmospheric stripe-like structures.
Spotted for the first time by Mariner 10 in the 1970s, they may be due to the presence of dust and aerosols in the atmosphere, but their true nature is still unexplained. "Venus Express has the tools to investigate these structures in detail. Studies have already begun to dig into the properties of the complex wind fields on Venus, to understand the atmospheric dynamics on local and global scales".
Venus Express also made use for the first time ever from orbit of the so-called 'infrared windows' present in the atmosphere of Venus if observed at certain wavelengths, it is possible to detect thermal radiation leaking from the deepest atmospheric layers, revealing what lies beneath the dense cloud curtain situated at about 60 Km altitude".
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Craters-Ghost_Crater_in_Lakshmi_Region-PIA00477-PCF-LXTT-IPF.jpgPossible "Ghost Crater" in Lakshmi Region (Absolute Natural Colors; credits for the additional process. and color.: Dr Paolo C. Fienga/Lunar Explorer Italia/Italian Planetary Foundation)76 visiteThis NASA - Magellan Spacecraft image covers an area of approximately 100 by 120 Km (such as 62,1 by 74,5 miles) and is located in the Lakshmi Region of Venus, at 47 North Latitude and 334 East Longitude. Due to the extremely dense Venusian Atmosphere, primary Impact Craters of less than a 3 Km (such as 1,863 mileS) diameter are, in fact, nonexistent on the Surface of this Planet. However, the Dark Circular Region and the associated Central Bright Feature visible in this frame are reasonably thought to be the remnants of a Meteoroid that was smaller than the size necessary to create an actual Impact Crater but, anyway, that was big enough to leave some scars on the Venusian Surface.
Entering the Venusian Atmosphere at a low velocity (approximately 350 meters/second - such as about 1260 Km per hour) the Central Bright Feature appears to be a Cluster of Small Secondary Impacts, Ejecta and Debris from the original Meteor that broke up in the Atmosphere and, litterally, fell down in pieces. Even though most of the Meteorite did not hit the Surface, the Atmospheric Shock Wave/s that were generated by the Impact Event, could have been great enough to modify the surrounding Region. One explanation for this radar Dark Circular Formation - called "Dark Margin" -, could be that the Shock Wave/s was/were energetic enough to pulverize some portion of the Venusian Surface (remember that smooth surfaces generally appear radar dark).
Another explanation is that the Surface nere, could be blanketed by a fine material that was formed by the original Meteor's break up through the Atmosphere. Just out of curiosity, more than half of the Impact Craters found on Venus have associated "Dark Margins", and most of them are prominently located left of center of the Craters themselves.
This frame (which is an Original NASA - Magellan Spacecraft Radio-Image published on the NASA - Planetary Photojournal with the n. PIA 00477), since it is just a Radio-Image of the Venusian Surface and NOT a real view of it, has been colorized, according to an educated guess carried out by Dr Paolo C. Fienga (LXTT-IPF), in what they could reasonably be its possible Absolute Natural Colors (such as the colors that a human eye would perceive if someone were onboard the NASA - Magellan Spacecraft and, once the thick layer of Venusian Clouds and Fogs is completely overcome, looked down, towards the Surface of Venus itself), by using an original technique created - and, in time, dramatically improved - by the Lunar Explorer Italia Team.MareKromium
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Lakhshmi_Planum-PIA00249.jpgMagellan Probe: radio image of Lakhsmi Planum and Danu Montes75 visiteCaption NASA originale:"Southwest Lakshmi Planum is bounded on the south by the Danu Montes. Lakshmi Planum is an elevated plateau that is bounded on all sides by mountain chains. Here, the Danu mountains have an angular fractured appearance. Chasms slice diagonally across the mountains in the lower left (southwest) corner of the image. Because of the steep slopes and the local relief of the mountains of several kilometers, these fault-bounded troughs appear to zig-zag through the mountains when, in fact, they are probably straight if viewed from above. The radar view provides a perspective that would place the viewer's eye to the right, 27 above the horizon. Thus, slopes facing to the right can be seen completely, though dark, and slopes facing away to the left appear shortened, often seen only as thin bright lines. In the center of the image is a low volcanic dome 20 Km in diameter. This type of volcanic feature frequently occurs on the low plains. This dome on the edge of Lakshmi is deformed and faulted where it has been affected by the forces that created the Danu mountains".
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Volcanoes-Maat_Mons-PIA00106.jpg3D view of Maat Mons75 visiteCaption NASA originale:"Maat Mons is displayed in this computer generated 3D view of the surface of Venus. The viewpoint is located 634 Km North of Maat Mons at an elevation of 3 Km above the terrain.
Lava flows extend for hundreds of kilometers across the fractured plains shown in the foreground, to the base of Maat Mons. The view is to the south with the volcano Maat Mons appearing at the center of the image on the horizon and rising to almost 5 Km above the surrounding terrain. Maat Mons is located at approx. 0,9 North latitude; 194,5 East longitude with a peak that ascends to 8 Km above the mean surface. Maat Mons is named for an Egyptian Goddess of Truth and Justice. Magellan synthetic aperture radar data is combined with radar altimetry to develop a three-dimensional map of the surface. The vertical scale in this perspective has been exaggerated 10 times".
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North_Polar_Regions-Ishtar_Terra.jpgIshtar Terra73 visiteIshtar Terra: this is a topographic map made by Don P. Mitchell, from Venera and Magellan altimetry data.
It shows the continent-sized highlands of Ishtar Terra, near the North Pole of Venus.
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Craters-Geopert_Crater-PIA00269.jpgMagellan Probe: radio image of Geopert-Meyer Impact Crater71 visiteCaption NASA originale:"During the third global cycle of Magellan's radar mapping mission, images were obtained at viewing angles that were slightly different than those used in the first two cycles. This strategy was designed to produce stereo image pairs, which take advantage of distortions induced by the different views to provide details of the surface topography. This is a stereo image pair of Crater Geopert-Meyer, named for the 20th Century Polish physicist and Nobel laureate (60 north latitude; 26,5 east longitude). The Crater, 35 Km (22 miles) in diameter, lies above an escarpment at the edge of a ridge belt in southern Ishtar Terra. West of the crater the scarp has more than 1 Km of relief. Perception of relief may be obtained with stereo glasses or a stereoscope".
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Craters-Somerville_Crater-PIA00100.jpgMagellan Probe: radio image of fractured Somerville Crater70 visiteCaption NASA originale:"This Magellan radar image is of a 'half crater' located in the rift between Rhea and Theia Montes in Beta Regio on Venus. The unnamed crater is 37 Km in diameter and is located at 29,9 North latitude and 282,9 East longitude. It has been cut by many fractures or faults since it was formed by the impact of a large asteroid. The eastern half of the crater was destroyed during the formation of a fault valley that is up to 20 Km wide and apparently quite deep. A north-south profile through the very center of this crater is visible as a result of the down dropping and removal of the eastern half of the crater".
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Venus-South_Polar_Vortex-12_VIRTIS_vortex_movie_H.gifThe restless South Pole of Venus (GIF-Movie - credits: ESA)70 visiteCaption ESA:"This video is composed of a set of images acquired by the Visible and Infrared Thermal Imaging Spectrometer (VIRTIS) on board ESAs Venus Express, during two observations slots in August 2007. The spacecraft was flying at a distance of about 65.000 Km from the Planet.
The video was obtained at 3.8-micrometre wavelength, allowing the instrument to see the cloud top thermal emission at an altitude of about 60-65 km.
The South Polar "Dipole", a complex atmospheric vortex-like feature situated over the South Pole of the Planet, can be clearly seen.
The change of the Polar Vortex shape in a time scale of a few hours is remarkably noticeable here"MareKromium
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Venusian_Surface-Venera_13-08.jpgVenus, from Venera 13 (Natural Colors; credits: Ted Stryk)66 visiteTed Stryk comments:"...Here is the other Venera 13 pan. The color data is OK on the sides, but in the center, all color data is nearly blank, making any color variations dubious in that part of the image...".
MareKromium
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Montes-Akna_Montes-PCF-LXTT.jpgAkna Montes (Natural Colors; credits: Lunar Explorer Italia)66 visitenessun commentoMareKromium
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Venusian_Surface-Venera_09-000.jpgVenera 9: the Spacecraft65 visiteGiven the intense temperatures and pressures of Venus, it is indeed impressive that Russian engineers were able to successfully land vehicles there 10 times during the 1970s and 1980s. These were Venera 7 to 14, and Vega 1 and 2 which deployed landers and balloon-born instrument packages. Although not designed to land, one of the free-falling Pioneer atmosphere probes gets honorable mention by surviving impact and continuing to transmit for a few minutes. The atmosphere of Venus is so thick that terminal velocity was only about 30 mph.
Seen above, the six-foot-tall Venera 9 lander was the first to take pictures of the surface, on October 20, 1975. The Venera orbiter and lander was a 10,000-pound spacecraft, one of the largest unmanned vehicles ever sent into space. Besides the camera system, the Venera landers measured the sky spectrum, atmospheric gases, cloud particles, and performed chemical analysis of surface rocks.
Looking out through 1 cm quartz pressure windows, Venera 9 to 14 captured spherical panoramas of 40 by 180. The cameras used a pivoting mirror and photomultiplier tube, giving remarkably low-noise images which were digitized to 9 bits per pixel. Venera 13 and 14 had two cameras and were able to capture images though clear, red, green and blue filters. So some portions of their panoramas contain color information. Venera 11 and 12 were unable to return pictures because of an equipment failure, but the rest of their experiments were successful.
These images have often been displayed as very poor quality pictures taken off film or even photographed off printed pages of Soviet journals. The images I show here are derived from the digital telemetry by the Russian image processing team. In the case of Venera 9 and 10, I undid a pixel replication and replaced it with a higher quality interpolation filter. For Venera 13 and 14, I combined the chroma signal from the dark somewhat noisy color images with the luminance signal of the clear-filter images.
Venera 13 and 14 survived longer than expected and returned dozens of images, repeating their program of clear and color scans. I hope to process that data into a super resolution image and to recalculate the perceptual color values.
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