Thursday, March 11, 2010

Europa from Voyager 2

When the Voyager Jupiter flybys were planned, very little was known about the Galilean moons.  Because it was impossible for both Voyagers to make a close flyby of each moon and still get to Saturn, planners were forced to be selective.  They gave the two largest moons, Ganymede and Callisto, a close flyby from each spacecraft.  Io, known to be an oddball, got an extremely close (by Voyager standards) flyby by Voyager 1.  Europa, the smallest of the Galileans, was given the lowest priority.  Voyager 2 made the only relatively close flyby, and it was relatively distant.  Still, it obtained some beautiful imagery.  There is a crescent image, which is the closest mosaic and has the best filter coverage, that has been reprocessed several times.  There is also a slightly more distant mosaic, taken from about 250,000 km.  It is limited in filter coverage, but shows Europa at a half phase, therefore showing significantly area.  The base color was created using orange filter data as red, blue as green, and a mix of violet and ultraviolet as blue. I have mixed the color data with OGV wide angle data taken later and reconstructed in the areas not covered by the later data.  The grayscale data is stacked and shown at 1.7x original size.  The result is one of the better global views of Europa presently available.

Here is a second version, leaning more heavily on the OGV data described above for color balance.

Processed Images Copyright Ted Stryk, Raw Data Courtesy NASA/JPL

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