Amateur image magician Ted Stryk has just provided me with a glorious set of global views of Jupiter's satellites, which he has produced from the Galileo data set. Galileo gave us our best views of these worlds but the data set has a variety of problems, most of which are rooted in the failure of the high-gain antenna. There are lots of data dropouts, for one thing -- places where there should be image data, but where there are only black pixels. Also, the Galileo imaging team was forced to compress their images onboard the spacecraft before transmitting them to Earth much more than they would have liked; compression introduces ugly artifacts in images, resulting in loss of detail. And they had to be very choosy about which filters they used for imaging -- so it is very rare to have the data necessary to make a view that looks like what human eyes would see. Ted has put a lot of effort into this data set, developing tricks to work around some of these problems, and produced images that look like they came from a different spacecraft. I'm slowly adding them to our image database, so I'll post a few here at a time.
Before I post these images I want to mention that in my enthusiasm for Ted's work I wish in no way to impugn the work done by the original Galileo imaging team. Ted's work is as much art as science, a labor of love that the actual science teams not only don't have time to do but also wouldn't want to do, because to make the images look this good Ted had to fill in gaps here and there, reducing the value of these images for science purposes but adding to their illustrative power.Callisto is an often-neglected satellite of Jupiter, usually regarded as the least interesting of the Galilean satellites because its surface is so very ancient. Here are two very pretty, subtly colored views that Ted managed to produce from the Galileo data. The first is the canonical view of Callisto: