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Venusian_Atmosphere-Airglow_VIRTIS_Anticlockwise-01.jpgThe "Airglow" of Venus53 visiteOne year has passed since 11 April 2006, when Venus Express, Europe’s first mission to Venus and the only spacecraft now in orbit around the planet, reached its destination. Since then, this advanced probe, born to explore one of the most mysterious planetary bodies in the Solar System, has been revealing planetary details never caught before.
Intensively visited by several Russian and American probes from the 60s to the early 90s, Venus has always represented a puzzling target for scientists worldwide to observe. Venus Express, designed and built in record time by ESA, was conceived with the purpose of studying Venus - unvisited since 1994 - in the most comprehensive and systematic way ever, to provide a long-due tribute to a planet so interesting, yet cryptic.
Using state-of-the-art instrumentation, Venus Express is approaching the study of Venus on a global scale. The space probe is collecting information about Venus’ noxious and restless atmosphere (including its clouds and high-speed winds, as seen from this video obtained with the VMC camera on board) and its interaction with the solar wind and the interplanetary environment. Last but not least, it is looking for signs of surface activity, such as active volcanism. MareKromium
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Venusian_Atmosphere-Airglow_VIRTIS_Anticlockwise-02.jpgThe "Glowing Oxygen" of Venus (false colors - elab. ESA)53 visite“During one year of observations, we have already collected huge amount of data, which is exactly what we need to decode the secrets of an atmosphere as complex as that of Venus,” said Håkan Svedhem, Venus Express Project Scientist at ESA. “Analysing it is an extreme effort for all science teams, but it is definitively paying back in terms of results.”
The first ever, terrific global views of the double-eyed vortex at Venus’ south pole, the first sets of 3D data about the structure and the dynamics of the sulphuric-acid clouds surrounding the planet in a thick curtain, temperature maps of the surface and the atmosphere at different altitudes, are only a few of the results obtained so far.
“Continuing at today’s rate, and on the basis of what we were able to see so far, there is no doubt that Venus Express will eventually allow a better global understanding of this planet,” continued Svedhem. “Not only will planetary science in general benefit from this, but also understanding Venus – its climate and atmospheric dynamics –will provide a better comprehension of the mechanisms that drive long-term climate evolution on our own Earth.”
MareKromium
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Venusian_Atmosphere-ORB157_00_17_WB_H.jpgVenusian Turbulence: South Polar Region53 visiteThis image of the Venusian South Polar Region was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 60.000 Km from the Planet’s surface.
The image, taken on the night-side of Venus at a wavelength of 1,7 micron, shows waves structure (faint light vertical streaks at the lower left part of the dark band in the centre-left side of the image) and a highly turbulent region (bottom left).
The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 kilometres high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.
The grey-scale of the image is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration. MareKromium
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Venusian_Atmosphere-ORB157_01_17_WB_H.jpgVenusian Turbulence: the Alpha Regio Area53 visiteThis image of the Venusian South Polar Region was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 65.000 Km from the Planet’s surface.
The image, showing a complex cloud system, was taken on the night-side of Venus (04:00 Local Time - V.L.T.), at a wavelength of 1,7 micron that allows viewing the deep atmospheric layers. The field of view covers an area located at approximately 20° West Longitude (diagonal top left to bottom right), spanning from the Equator (at the horizon on the right) to 60° Southern Latitude (top left corner of the image).
The grey-scale of the image is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.
The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 kilometres high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.MareKromium
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Venusian_Atmosphere-ORB157_02_17_WB_H.jpgVenusian Turbulence: the Alpha Regio Area53 visiteThis image of the Venusian South Polar Region was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 53.000 Km from the Planet’s surface.
The image, taken on the night-side of Venus at a wavelength of 1,7 micron, shows waves structure (faint light vertical streaks at the lower left part of the dark band in the centre-left side of the image) and a highly turbulent region (bottom left).
The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 Km high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.
The grey-scale of the image is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.MareKromium
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Venusian_Atmosphere-ORB157_03_17_WB_H.jpgVenusian Turbulence: the Near-Equatorial Region54 visiteThis image of the Near-Equatorial Region of Venus was acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from a distance of about 37.000 Km from the Planet’s surface.
The image, taken on the night-side of Venus at a wavelength of 1,7 micron, provides a close-up view of a highly turbulent region, with irregular and warped clouds, which is common at these low latitudes. This is different from what happens at higher latitudes (pole-ward) where clouds are generally streaky and more regularly shaped.
The gray ‘bubble’ slightly below the centre of the image is located at about 27° Southern Latitude and 7° Western Longitude, and has a diameter of about 300 Km.
The Alpha Regio area is at the bottom left of the image. This area is characterised by a series of troughs, ridges, and faults that are oriented in many directions, with surface features that can be up to 4 Km high. It is not yet clear if atmospheric turbulences may be induced by the rough topography below the clouds.
The grey-scale of the image is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.MareKromium
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Venusian_Atmosphere-ORB157_multiple_H.jpgVenusian Turbulence: Image Mosaic of the (visible) Venusian Cloud System53 visiteThis image is a composite of four different views of the Venusian Cloud System.
The images were acquired on 24 September 2006 by the Ultraviolet, Visible and Near-Infrared Mapping Spectrometer (VIRTIS) on board ESA’s Venus Express, from distances of about 65.000 Km (top left), 60.000 Km (top right), 53.000 Km (bottom left), 37.000 Km (bottom right) from the Planet’s surface.
The images, showing a complex cloud system, were taken on the night-side of Venus (04:00 V.L.T.), at a wavelength of 1,7 micron that allows viewing the deep atmospheric layers.
The grey-scale of the images is such that black means more transparency, therefore less clouds, while white means more opacity, therefore more cloud concentration.MareKromium
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Venusian_Atmosphere-ORB410_411_tot_H1.jpgThe Venusian Atmosphere under the Messenger53 visiteCaption ESA:"The images in this panel were obtained by the VIRTIS imaging spectrometer on board Venus Express on 5 and 6 June 2007, before and after MESSENGER’s closest approach to the Planet. These panels from VIRTIS provide a night-side view of the same Region that Messenger flew over and imaged.
The images where obtained at 1,7 micrometres, revealing atmospheric details down to an altitude of 50 Km from the surface".MareKromium
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Venusian_Atmosphere-VI410_01_23_with_spot_H1.jpgThe Venusian Atmosphere under the Messenger56 visiteCaption ESA:"This grey-scale image, obtained by the VIRTIS instrument on board ESA’s Venus Express, shows the Atmospheric Region of Venus over which NASA’s MESSENGER Spacecraft passed on 5 June 2007. The Region of MESSENGER’s closest approach is in the night side (marked by a circle).
VIRTIS obtained this image at 2,3 micrometres from about 35.000 Km from the Planet, on the night side.
This wavelength makes it possible to probe the atmosphere down to about 30 Km from the surface. Much of the contrast in this image is due to the structure of the lower clouds.
The bright areas correspond to radiation from the lower atmospheric layers, indicating that the clouds are thinner in those areas. At the 2,3-micrometre wavelength it is possible to study not only the morphology of the cloud layers, but also its chemical composition (such as Carbon Monoxide - CO -, Water - H2O -, Sulphur Dioxide - SO2 -, etc)".MareKromium
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Venusian_Atmosphere_and_the_Solar_Wind-Interaction.jpgInteraction between Venus and the Solar Wind55 visiteCaption ESA:"Mars, Earth and Venus are immersed in a flow of plasma, a ionised and highly variable gas originating from the Sun, called the Solar Wind. While Earth has a Planetary Magnetic Field, which can deviate its flow, Venus (and Mars) don’t.
Gases in the upper atmospheres of these Planets are ionised, and can thus interact with the Solar Wind. Venus is as large as Earth and it is difficult for its Atmosphere to escape due to the Planet’s Gravity. The Solar Wind is the best source of energy to accelerate the upper atmosphere’s charged particles, giving them enough energy to escape. This is why Venus loses its atmosphere due to interaction with the Solar Wind.
To understand this phenomenon, the key questions that the instruments studying plasma on Venus Express must answer are: what and how much of the Atmosphere is lost, and where is it lost? Right now, solar activity is at its minimum in the 11-year cycle, making the Solar Wind weaker than average.
The critical question now is how solar wind interacts with Venus when solar activity is low".MareKromium
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Venusian_Clouds-29_VM_Pericentre_mosaic_H.jpgChaotic "Cloud Patterns" at Venus53 visiteCaption ESA:"This mosaic of Venus’ cloud tops was put together with several images obtained by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express. The images where taken in the ultraviolet (365-nanometre wavelength) on 15 August 2006 at distances from 5000 to 1000 Km from the Planet.
The picture clearly shows streaks, wave trains and convection cells. The elongated orbit of Venus Express allows one to zoom into the cloud features as the Spacecraft approaches the Planet. This mosaic shows that mottled and chaotic cloud patterns at low latitudes give way to oriented streaks at about 15° South.
This behaviour indicates transition between two different cloud motion regimes – a ‘dynamic’ regime dominated by local convection where the Sun light hits the Planet perpendicularly (so-called "Sub-Solar Point") - and a more regular, quasi-laminar-flow regime".
MareKromium
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Venusian_Clouds-IR-PIA00124.jpgLow altitude Venusian clouds (false colors)91 visiteThis false-color image is a near-infrared map of lower-level clouds on the night side of Venus, obtained by the Near Infrared Mapping Spectrometer aboard the Galileo spacecraft as it approached the planet's night side on February 10, 1990. Bright slivers of sunlit high clouds are visible above and below the dark, glowing hemisphere. The spacecraft is about 100.000 Km above the planet. An infrared wavelength of 2,3 microns (about 3 times the longest wavelength visible to the human eye) was used. The map shows the turbulent, cloudy middle atmosphere some 50-55 Km above the surface, 10-16 Km below the visible cloudtops. The red color represents the radiant heat from the lower atmosphere (about 400° Fahrenheit) shining through the sulfuric acid clouds, which appear as much as 10 times darker than the bright gaps between clouds. This cloud layer is at about -30° Fahrenheit, at a pressure about 1/2 Earth's surface atmospheric pressure. Near the equator, the clouds appear fluffy and blocky; farther north, they are stretched out into East-West filaments by winds estimated at more than 150 mph, while the poles are capped by thick clouds at this altitude.
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