Venusian Veil and Vortex

ESA's Venus Express spacecraft is now officially in the operational phase of its mission and is starting to produce quite a lot of science output. The craft is basically a clone of Mars Express so has many of the same instruments. Unlike Mars, Venus has a pretty exciting and substantial atmosphere so Venus Express will not be taking amazing 3D images of the surface like Mars Express, but monitoring the clouds, winds, distribution and chemical composition of Venus' thick blanket. That doesn't make it boring though because Venus is throwing up some surprises.

Let me start by giving you a lovely animation showing the approach of Venus Express towards Venus on 22 May. The animation is created from UV images taken by the Venus Monitoring Camera (VMC) as the spacecraft was approaching the northern hemisphere. It starts out at a distance of about 39,100 from the surface and ends at 22,600 kilometres. Beautiful.

UV images taken by the Venus Monitoring Camera (VMC) on board ESA’s Venus Express spacecraft on 22 May 2006. Full resolution animation (2 MB) CREDIT: ESA/MPS, Katlenburg-Lindau, Germany
If you remember the first image to be sent back by Venus Express in May, you will perhaps recall the dark, double-eye vortex seen over the south pole of the planet. Amongst the latest release of images/videos is an animation showing the vortex changing over time (below). Pretty amazing stuff.

Vortex on Venus
An animation of infrared images taken by the Ultraviolet/Visible/Near-Infrared spectrometer (VIRTIS) on board ESA’s Venus Express. It shows a close-up view of the double-eyed vortex at the south pole of Venus. Full resolution image (4.1 MB) CREDIT: ESA/VIRTIS/INAF-IASF/Obs. de Paris-LESIA

Each wavelength of light in the VIRTIS instrument, is able to examine different depths (altitudes) in the atmosphere so it has also been possible to build up a more three dimensional idea of the feature. According to Pierre Drossart, VIRTIS co-Principal Investigator, from the Observatoire de Paris, France

"It is like if we were looking at different structures, rather than a single one. And the new data we have just started gathering and analysing reveal even stronger differences".

There are a whole slew of other exciting results concerning the depth of the atmosphere as observed in stellar occultation measurements, tracking of cloud motions to infer wind speeds and the confirmation that 'UV absorbers' - which absorb almost half of the solar energy received by the planet - exist high in the atmosphere. Head over to the ESA press release to gore yourself on the details and pretty pictures.

Posted in astro blog by Stuart on Thursday 13th Jul 2006 (12:03 CEST) | Permalink
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