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Global True Color View Of Venus?
elakdawalla
post Aug 8 2005, 06:53 PM
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I'm creating a website with views of the worlds of the solar system, to scale with each other (it'll march up and down the few orders of magnitude necessary), and I am having a terrible time finding a global view of Venus to include in it that fits the criteria I'm trying to apply. To the extent possible, I am searching for:

- Full-disk, global view
- Minimum phase angle available
- Approximate true color, as would be perceived by a human observing the globe from space

For Venus, the only global views I am finding are either based on Magellan data (radar views, nothing like what a human would see) or are colorized ultraviolet views (which greatly overemphasize the visibility of cloud patterns in the Venusian atmosphere). I've seen the lovely partial global view of Venus on Don Mitchell's website -- that's the sort of thing I'm looking for, but I need a full disk. Does anybody have any suggestions? Anybody done any work with Mariner 10 or Galileo data that produces a nice, realistic view?


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Guest_BruceMoomaw_*
post Aug 8 2005, 06:58 PM
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You might look into the images from Pioneer 12's spin-scan photopolarimeter -- it took visual as well as UV images of Venus (I've seen one, although it was only a half-Venus). Surely there are a few full-disk visual images of Venus in its 14-year backlog of data.
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JRehling
post Aug 8 2005, 09:02 PM
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QUOTE (elakdawalla @ Aug 8 2005, 11:53 AM)
I'm creating a website with views of the worlds of the solar system, to scale with each other (it'll march up and down the few orders of magnitude necessary), and I am having a terrible time finding a global view of Venus to include in it that fits the criteria I'm trying to apply.  To the extent possible, I am searching for:

- Full-disk, global view
- Minimum phase angle available
- Approximate true color, as would be perceived by a human observing the globe from space
*


When I wanted the same thing, I once took a global image of Titan and played with the color until it was white instead of orange. Another time, I used Uranus. A blank sphere is a blank sphere...

Alternately, I might take a cylindrical map of Venus and project it onto a sphere.

If you want the genuine article, I don't think any exist, with Earth-based telescopy coming closest.
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tedstryk
post Aug 8 2005, 10:09 PM
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Yes, but I don't think it took multiband images in the visible. Just visible and UV.


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4th rock from th...
post Aug 8 2005, 11:48 PM
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My best attempts, using Mariner 10 "clear" and "blue" filter images:

Attached Image
Attached Image


These are two versions of the same image. One is processed to show a neutral white Venus, the other was based on the yellow atmosphere seen from the surface.

I've searched the internet for some Venus visible specta and found some interesting data. I'll post some images based on this data but for now my conclusion it that the planet's general color is pale-yellow, with some bright white-blue clouds (better visible in UV).


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4th rock from th...
post Aug 8 2005, 11:55 PM
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Attached Image


Ok, here's a Venus atmospheric profile. It shows brightness and color variations from 70km up to the surface. On the right part of the image brighness variations were removed and only color changes remain.

When I have time I'll post some more Venus stuff I have around ;-)


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elakdawalla
post Aug 10 2005, 03:39 AM
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QUOTE (4th rock from the sun @ Aug 8 2005, 04:48 PM)
My best attempts, using Mariner 10 "clear" and "blue" filter images:

*


These are exactly the kind of thing I was looking for, thank you! I'm glad that someone got around to giving this a try.

The atmospheric profile is also very cool information. I assume it could be used to make some simulated views of Venus as you descend through the clouds, just as Rene Pascal did for Titan?

Emily


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4th rock from th...
post Aug 10 2005, 12:44 PM
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Check my page http://www.astrosurf.com/nunes/explor/explor_m10.htm for some more images.

But take into account that the human vision is very different from a camera. Venus clouds are VERY bright, so I don't know what a person would see on that conditions.

They can be used on your page if you like, just put a link to my page somewhere and give credit for the image processing ;-)

Yes, you could simulate going down Venus atmosphere, that's a very interesting idea.
One more thing to do when I have time....


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4th rock from th...
post Aug 10 2005, 07:10 PM
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Attached Image


OK, here's all the data I have. This atmospheric profile updates the previous one and is a better match to the sky color visible from the surface.

Still, all the data points to a green/cyan Venusian color when seen from space!


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planet_guy
post Aug 25 2005, 01:17 PM
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If you are interested in the surface stuff done by VIRTIS on VEX you can take a look at
http://solarsystem.dlr.de/TP/VIRTIS_en.shtml
and
http://irsps.sci.unich.it/~luciam/VEX/
The beauty of VIRTIS is that we will for the first time get global multispectral imaging from the surface of Venus over a long time period.
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algorimancer
post Aug 26 2005, 01:09 PM
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QUOTE (planet_guy @ Aug 25 2005, 08:17 AM)
If you are interested in the surface stuff done by VIRTIS on VEX you can take a look at
http://solarsystem.dlr.de/TP/VIRTIS_en.shtml
and
http://irsps.sci.unich.it/~luciam/VEX/
The beauty of VIRTIS is that we will for the first time get global multispectral imaging from the surface of Venus over a long time period.
*


Of course, if Mars Express is any guide, we won't get to see much of the results :/
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tedstryk
post Aug 26 2005, 02:00 PM
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QUOTE (planet_guy @ Aug 25 2005, 01:17 PM)
If you are interested in the surface stuff done by VIRTIS on VEX you can take a look at
http://solarsystem.dlr.de/TP/VIRTIS_en.shtml
and
http://irsps.sci.unich.it/~luciam/VEX/
The beauty of VIRTIS is that we will for the first time get global multispectral imaging from the surface of Venus over a long time period.
*



Great links! I wonder about something...it is thought that, despite up to 16 km/pixel resolution, atmospheric bluring will reduce resolution to 50-100 km. With this being a hyperspectral imager, are they sure that there are no holes where better might be obtained....I know the predictions, but, as they say, he who lives by the crystal ball eats glass. I also wonder if something like a spacecraft role could be used in selected areas for coverage inside of 10,000 km. I am really confused about coverage though. Some of the documents indicate that there will only be coverage of the southern hemisphere, but others indicate the best coverage will be of the northern hemisphere!


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planet_guy
post Aug 26 2005, 03:18 PM
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well the 16km/pix are using the 'holes' smile.gif the holes are in the co2 absorption, but you still have the clouds which are responsible for the blurring. of course since it has not been tried before these are only very cautious predictions. it might turn out to be somewhere between 16 and 50km/pixels
regarding the coverage - it will be mainly for the southern hemisphere. everything in the north can be done only by stacking several orbits or (maybe) by trying some slew of the spacecraft. However, surface imaging is not the main task of VEX so this will surely not be done in the beginning of the mission
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tedstryk
post Aug 26 2005, 03:25 PM
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QUOTE (planet_guy @ Aug 26 2005, 03:18 PM)
well the 16km/pix are using the 'holes' smile.gif the holes are in the co2 absorption, but you still have the clouds which are responsible for the blurring. of course since it has not been tried before these are only very cautious predictions. it might turn out to be somewhere between 16 and 50km/pixels
regarding the coverage - it will be mainly for the southern hemisphere. everything in the north can be done only by stacking several orbits or (maybe) by trying some slew of the spacecraft. However, surface imaging is not the main task of VEX so this will surely not be done in the beginning of the mission
*


Sounds like an extended mission task. 16 km was the resolution/pixel, 50-100 was the estimated realistic resolution, thanks to the atmosphere. I am just hoping that the predictions don't hold up cool.gif


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planet_guy
post Aug 26 2005, 03:28 PM
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trust me.. I'm also hoping the predictions are wrong wink.gif
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