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Venusian_Clouds-VI410_411_23_tot.gifVenusian Cloud Structure (GIF-movie)53 visiteCaption ESA:"This movie consists of a sequence of six images obtained by the VIRTIS imaging spectrometer on board ESA’s Venus Express on 5 and 6 June 2007, before and after NASA MESSENGER’s closest approach to the Planet. The image sequence, obtained by VIRTIS, provides a night-side view of the same region that Messenger flew over and imaged.
They were obtained at 1,7 micrometres, revealing atmospheric details down to an altitude of 50 Km from the surface".MareKromium
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Venusian_Clouds-Venus_Express-VOI_composit.jpgVenusian cloud structures: day-side and night-side53 visiteThe early infrared image making use of the windows, show complex cloud structures, all revealed by the thermal radiation coming up from different atmospheric depths. In this colour scheme, the brighter the colour (that is, the more radiation comes up from the lower layers), the less cloudy is the observed area.
During capture orbit, preliminary data about the chemical composition of the Venusian atmosphere were also retrieved. Venus’ atmosphere is mainly composed of Carbon Dioxide (CO2). The incoming solar radiation dissociates this molecule into Carbon Monoxide (CO) and Oxygen (O2) in the upper atmospheric layers. In fact, Venus Express has already spotted the presence of an Oxygen airglow high in the atmosphere. However, Venus Express has revealed the presence of Carbon Monoxide as low as the cloud-layer top.
Scientists will continue the data analysis and retrieval to understand the phenomenon, which is very important to clarify the complex chemical processes and cycles at work in the atmosphere of Venus under the influence of solar radiation.
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Venusian_Clouds_Altimetry-2008-04-03438_Figure_3_H.jpgAltimetry of Venus Clouds' Top54 visiteCaption ESA:"A Venus Monitoring Camera UltraViolet image with a superimposed colour mosaic, showing the altitude of the cloud tops.
The colour mosaic was derived from simultaneous pressure measurements by the Visible and Infrared Thermal Imaging Spectrometer".MareKromium
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Venusian_Clouds_and_Haze-27_VMC_polar_views_H.jpgVenusian "Variable Clouds" and "Hazes"53 visiteCaption ESA:"This is a composite of several ultraviolet (365-nnmts) images taken with the Venus Monitoring Camera (VMC) on board ESA’s Venus Express.
These images show variability of the clouds and hazes in Venus’ South Polar Region.
The South Pole is at the Terminator in the bottom-left of the images.
Super-Rotation, a phenomenon where cloud layers on Venus rotate much faster than the surface below, is in the anticlockwise direction. The period of Super-Rotation varies between 3 and 5 days, depending on the latitude.
The images a, b and c in the top row were taken between 27 and 30 June 2006, at a distance of about 65.000 Km from the Planet.
It is obvious from the pictures that the near-polar features vary from one day to another.
An extreme case of such variability is shown in Figure d (obtained on 13 January 2007, from about 35.000 Km). The bright haze located above the absorbing cloud layer has expanded to 35º South and has also become denser, masking all features except the oval. This dense haze disappeared within a day, probably due to very quick coagulation of aerosols making up the haze.
The figure in panel e (obtained on 27 December 2006, from about 38.000 Km) shows the full view of the Southern Hemisphere from the Equator (right) to the Pole".MareKromium
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Venusian_Clouds_and_winds_in_the_infrared_H.jpgVenusian cloud structures - Night view (2)56 visiteOriginal ESA caption:""We are also collecting the first information on the minor chemical components of the atmosphere, such as CO - Carbon Monoxide" added Pierre Drossart.
"With VIRTIS we can see in the atmosphere of the southern hemisphere deeper than any other previous mission, and we started gathering data on the yet unknown chemistry of the lower atmospheric layers, to build a global picture. Studying the variation of minor chemical compounds over different latitudes and depths is also a very useful tracer for the atmospheric global motion".
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Venusian_Clouds_tracking_infrared_2_b_H.jpgVenusian cloud structures - Night view (1)54 visiteOriginal ESA caption:"Tracking cloud motion and starting to characterise the wind speed is an exercise that the Venus Express scientists have already started. A spectacular night view of the mid to low atmospheric layers over low latitudes (between 20º and 90 º South) by VIRTIS, show clouds being clearly pushed by winds.
"We can now make a first qualitative assessment of the wind fields and circulation, which is comfortably matching with previous measurement from the Galileo mission over the North Pole", said Giuseppe Piccioni.
"We are now collecting more data from different atmospheric depths, to be able to provide the first precise numbers, possibly in the near future".
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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 40º by 180º. 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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Venusian_Surface-Venera_09-001.jpgVenus from Venera 9 - October, 22, 1975 - enhanced and processed image274 visiteOsservate ora il panorama ripreso da Venera 9, sette anni prima: tutto quanto molto simile tranne, forse, la sensazione che in quest'area, al momento dello scatto della fotografia, non stesse "piovendo" (guardate bene l'immagine scattata da Venera 13 e cercate di cogliere la diversità, in termini di riflettenza, fra le due superfici riprese).
Notate, infine, che questa fotografia è l'UNICA che Venera 9 riuscì a scattare e ad inviare a Terra durante la sua breve permanenza sul Pianeta: solo 53 minuti, ma comunque un'eternità ed un grandissimo successo, considerata la tecnologia disponibile negli anni '70/'80 (in rapporto a quella posseduta oggi)!
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Venusian_Surface-Venera_09-002.jpgVenus from Venera 9 - October, 22, 1975 - The Original Frame177 visiteEd ora qualche dato ottenuto dalle Sonde: temperatura minima al suolo: 465°C, max 485°C; pressione superficiale minima: tra le 90 e le 94 volte la press. terr. al livello del mare.
Alcuni elementi atmosferici: HCl, HF, I e Br; vento: intorno ai 3,5 Km/ora; non si sono rilevate polveri in sospensione; altezza delle nuvole dal suolo: circa 30 Km.
Un mondo decisamente diverso dal nostro e dall'ormai familiare Marte, non credete?!?
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Venusian_Surface-Venera_10-00.jpgVenus from Venera 10 - October, 25, 1975 - The Original Frame194 visiteNostante la fittissima schermatura costituita dalle nuvole (35/40 Km di spessore), però, la luminosità del paesaggio su Venere sarebbe in ogni caso molto elevata. Per quanto attiene le rocce piatte riprese dal Lander Sovietico (in parte ricoperte da polveri), diremmo che si potrebbe trattare di rocce basaltiche, non troppo diverse da quelle che potremmo trovare sia su Marte, sia sulla Terra stessa, in prossimità di aree vulcaniche attive.
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Venusian_Surface-Venera_10-01.jpgVenus from Venera 10 - October, 25, 1975 - enhanced and processed image421 visiteAd ogni modo, in questa foto, ripresa dalla Sonda Venera 10 il 25 Ottobre 1975, possiamo finalmente vedere la superficie di Venere.
La Sonda Sovietica sopravvisse solo 65' sul Pianeta e, al momento di scattare la fotografia, il Sole si trovava vicino allo zenith.
Cosa avremmo visto guardando in alto?
Un cielo completamente nuvoloso ed intensamente illuminato da luce bianca.
Diciamo che lo spettacolo sarebbe stato simile a quello visibile in un torrido giorno dell'Estate terrestre, allorchè il cielo viene invaso da formazioni compatte di nuvole bianche.
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Venusian_Surface-Venera_13-00.jpgVenus from Venera 13 - March, 1, 1982 - Two Original Frames226 visiteE adesso facciamo un salto al 1° Marzo 1982: ancora un landing positivo di una Sonda Sovietica - Venera 13 - che resisterà per ben 2 ore e 7 minuti sulla superficie del Pianeta (record!).
Più tempo e, quindi, più immagini riprese (e, questa volta, ne troviamo anche una a colori che Vi proporremo in seguito).
Le caratteristiche superficiali di Venere, a quanto si vede, sembrano non cambiare: rocce piatte, parzialmente frammentate, e pietrisco più sottile (con, forse, anche delle sferule simili a quelle trovate su Marte, in Area Meridiani Planum).
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