Galileo images and mosaics of Europa |
Galileo images and mosaics of Europa |
Aug 22 2005, 04:03 AM
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Interplanetary Dumpster Diver Group: Admin Posts: 4404 Joined: 17-February 04 From: Powell, TN Member No.: 33 |
I have worked on sprucing up some global views of Europa from Galileo. There are a few more global views I hope to get to eventually. But the best two at nearly full phase benefited a lot.
[Moderator note: There are several more threads containing Galileo Europa images but they all contain several inactive image links. The main threads are: http://www.unmannedspaceflight.com/index.php?showtopic=2016 http://www.unmannedspaceflight.com/index.php?showtopic=2174 http://www.unmannedspaceflight.com/index.php?showtopic=2222 http://www.unmannedspaceflight.com/index.php?showtopic=2082 http://www.unmannedspaceflight.com/index.php?showtopic=2142 ] -------------------- |
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Jan 2 2014, 04:32 PM
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IMG to PNG GOD Group: Moderator Posts: 2254 Joined: 19-February 04 From: Near fire and ice Member No.: 38 |
Here is the I33 color image, the range is 1.9 million km. It's from 756 nm, green and violet. As in the G28 image in my previous post the color was probably a bit strange but here I attempted to correct it. I used the C10 color composite as a guide but I still have some doubts about the resulting color. Here the green image has been multiplied by 0.92 and the synthetic blue image by 0.98. The original images were rather blurry so the final image has been sharpened quite a bit:
And now two observations from the G7 flyby, one of the better non-targeted Europa flybys. Here is an approximately true color image of Tyre Macula from a distance of 30,000 km. It's created from from 968 nm, green and violet images. This is from AI8 summation mode images so the resolution is ~600 m/pixel. North is up. A fairly well known false color version from the same data can be seen here. But here is the true color image: And here is a four frame mosaic from the G7ESAPEXCR observation. The resolution is ~500 m/pixel. Actually this observation consisted of five frames but only a tiny strip of frame three was downlinked. For context, lower resolution data is included. In general this terrain is relatively poorly imaged. And here is a schematic global view showing the location of the G7ESAPEXCR observation. The subspaccraft longitude is ~115 degrees west. I used a slightly modified version of the USGS Europa map. Processing the Galileo data can be horribly frustrating. I inevitably start thinking of what could have been. Galileo flew by Europa at a range of 25,000 km during the G7 orbit - and with relatively poorly imaged terrain in view. Under normal circumstances it could easily have imaged this entire terrain at 1 km/pixel or better - and at several wavelengths. Hundreds of images would have been acquired during the G7 Europa flyby. But due to the HGA failure this was not possible, only a tiny part of this terrain was imaged at 1 km/pixel or better. And the reality is that considering how disastrous the HGA loss was, what Galileo managed to do over its mission really was a miracle. |
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Jan 12 2014, 04:22 PM
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Senior Member Group: Members Posts: 2530 Joined: 20-April 05 Member No.: 321 |
Great images, Bjorn.
I wonder if a color model of Europa could be constructed that assumes that the composition (in terms of color, not necessarily chemically), locally, is always at some point on a continuum between icy and non-icy. Then the limited set of color images could be used to model the obviously complex photometry function of both the icy and non-icy terrain, and re-render any B/W images according to that model. It seems like in the case of Europa, a model that simple wouldn't be far from the mark. |
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