Monday, March 8, 2010

Color Gish Bar Mosaic from I32

Last week, I posted a new version of the global color mosaic the Galileo spacecraft acquired in July 1999.  This week we take a look at a mosaic from a Galileo flyby in October 2001 of the blog namesake, the volcano Gish Bar Patera (right frame), and the terrain to the west of it.  The mosaic has a resolution of 267 meters per pixel and is centered near 17° N, 95° W.  In this version, I have combined the brightness information from the three frame mosaic (32ISGSHBAR01) with the color data from the C21 mosaic from July 1999.

Be sure to DOWNLOAD [3.56 MB PNG image] the full-resolution version (Blogger automatically shrinks the version linked above).

A few things of note in this color mosaic.  First, in the two years between the time the color data was taken and the higher resolution clear filter mosaic, several volcanic eruptions and other surface changes occurred at Gish Bar.  Between July and October 1999, the southeastern portion of the patera darkened, possibly due to a major eruption in August that year.  During the October 2001 flyby, Gish Bar was undergoing another major eruption, which likely generated the dark flow on the western side of the patera.  Some of the dark flows seen in the July 1999 data have since brightened, which appear purple-ish in this mosaic.  As a result of the surface changes, some of the colors seen in the patera should probably taken with a grain of salt, which is why I preferred not to do this before.

Outside of Gish Bar Patera, the terrain is mostly yellowish, with a few key variations seen.  For example, the mountain Monan Mons, the southern portion of which is seen in the left frame, has bright material across much of the debris deposits to the east of it, suggesting that sapping of sulfur dioxide within the mountain may have played a role in the degradation of that structures.  There also appear to be color differences between the bright yellow plateau to the west of Gish Bar (seen in the middle frame with the Y-shaped dark fracture running down the middle of it) and the surrounding, greenish plains.

Interesting stuff.

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