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First data from Venus Express !
Rakhir
post Apr 13 2006, 03:22 PM
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Unexpected detail in first-ever Venus south pole images

http://www.esa.int/SPECIALS/Venus_Express/SEMUTYNFGLE_0.html
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JRehling
post Apr 13 2006, 04:24 PM
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Good stuff. Kudos to the team for successful operations and a quick first release.

I'm curious as to the wavelengths in the dayside image. It's probably stretched beyond "human" RGB to show that much detail, but it would be fantastic to have a multispectral dataset and sate some curiosity about what a "true" color spacecraft image of Venus would look like. VEx will answer this question as well as one could expect.

The IR nightside makes me wonder about the prospects of seeing the surface through the cloud layers. That's a whole lot of cloud signal. Maybe greater temporal coverage will show us the surface in peeks here and there. Also, other IR may show the surface signal better.

I'm surprised how the UV image looks -- quite different from the Pioneer images. Lots of calibration questions.
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Rakhir
post Apr 13 2006, 04:55 PM
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QUOTE (JRehling @ Apr 13 2006, 06:24 PM) *
Good stuff. Kudos to the team for successful operations and a quick first release.

We just have to hope that the next releases will be as quick as the first one.
However, given the PR history and what was available for the VOI, it is probably only a dream rolleyes.gif
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ollopa
post Apr 13 2006, 05:37 PM
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Anyone here smart enough to work out the lat/lon gridlines for these first images? Presumably a half decent astronomy programme would at least tell where the subsolar point was on Venus @ say 9:07 UT on the 11th..
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JRehling
post Apr 13 2006, 06:33 PM
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Well, since the axial inclination is only 3 degrees, you can count on the apparent pole always being pretty close to the actual pole. There's only one real degree of freedom in the subsolar point.
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dilo
post Apr 13 2006, 08:27 PM
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UV map seems to show surface details, but this should be only my impression (atmosphere should be more transparent in IR and visible features do not match with radar maps around south pole...).
Attached Image

This is a small, naif combination of visible + UV image (former was veirated toward red while latter was detail/contrast enhanced).


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Julius
post Apr 13 2006, 09:23 PM
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The deepsest features visible are estimated at 55 km above the Venusian surface.Thats according to ESA website.
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JRehling
post Apr 14 2006, 01:11 AM
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UV shouldn't ever show surface detail, I don't think. The clouds reflect UV and absorb it, but shouldn't let very much pass through. There is an unknown UV absorber that "marks" some clouds and leaves others unaffected.

IR will not show the surface at many wavelengths of IR. The temperature of Venus produces an IR glow in many wavelengths, and CO2 absorbs it at others. It is not so neat a situation as at Titan.
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Guest_BruceMoomaw_*
post Apr 14 2006, 01:48 AM
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Nope, UV NEVER punches through to the surface -- but some limited near-IR spectral bands do, and Galileo's near-IR maps of Venus in those wavelengths during its flyby provided a temperature map that matched up beautifully with radar maps of Venus' surface topography. Venus Express' far more detailed and sensitive surface temperature maps should be able to reveal any small regions of current surface volcanism. The real question is whether they will be able to pierce the cloud interference enough to also provide at least a little data on surface composition near the north pole (or at least a distinction between granitic and basaltic rocks).
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deglr6328
post Apr 14 2006, 05:08 AM
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Even if the atmosphere were cloud-free I suspect that the extreme rayleigh scattering of UV light and the immense thickness of the atmosphere alone would preclude the possibility of imaging any detail. Here's an image of the CN tower which has been ruined by UV dispersion.

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elakdawalla
post Apr 14 2006, 10:41 PM
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I got some more info out of Kevin Baines about these images...
http://www.planetary.org/news/2006/0414_Fi...mages_Peel.html

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RNeuhaus
post Apr 15 2006, 01:01 AM
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QUOTE (elakdawalla @ Apr 14 2006, 05:41 PM) *
I got some more info out of Kevin Baines about these images...
http://www.planetary.org/news/2006/0414_Fi...mages_Peel.html

Very good explaining. From that URL, I was able to understand better about the different layers of colours around the Venus' South pole. Neither VIRTS (Visible and Infrared Thermal Imaging Spectrometer) and VMC (Venus Monitoring Camera) are able to map the Venus Surface. So Venus Express will not take the same pictures as did the extint Magellan probe, won't it?

Rodolfo
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Guest_BruceMoomaw_*
post Apr 15 2006, 02:25 AM
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Not at all -- no radar on this one. However, VIRTIS WILL be able to provide a good deal of entirely new and important surface information -- which, combined with its atmospheric science, is why it's the single most important instrument on the craft.

Unfortunately, the currently-stuck PFS is the second most important; and it's important for the two instruments to make their atmospheric observations simultaneously. For this reason, I imagine they will put in considerable effort -- and even be willing to run some risks -- to unstick it.
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RNeuhaus
post Apr 15 2006, 01:29 PM
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I was not aware of Planet Fourier Spectometer (PFS) that is stuck now. What was the problem?

An extract from ESA's portal on Venus Express

PFS will be able to measure the temperature of the atmosphere between altitudes of 55100 kilometres at a very high resolution. It will also be able to measure the surface temperature and therefore be able to search for volcanic activity. In addition to its temperature measurements, PFS will be able to make composition measurements of the atmosphere.


Will the PFS be able to deduct the surface contour according to its temperature? I don't believe it as a reliable indicator since the surface might have different refraction/absorption properties of light/heat.

QUOTE
VIRTIS WILL be able to provide a good deal of entirely new and important surface information


What kind of surface information will VIRTS provide?

Rodolfo
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Rakhir
post Apr 15 2006, 01:34 PM
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QUOTE (RNeuhaus @ Apr 15 2006, 03:29 PM) *
I was not aware of Planet Fourier Spectometer (PFS) that is stuck now. What was the problem?

Rodolfo


Rodolfo,

check this thread for the stuck PFS.

-- Rakhir
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