Galileo's Photo Contest

A macula is a dark spot that appears to be flat, or nearly so. It might be the scar of a crater on Europa's icy surface, which can flow and flatten out more easily than rocky material could. Studying a macula can tell scientists about how the frozen crust moves and flows, in turn telling about its composition and thickness. (Remember, it is thought Europa has an icy crust covering a slushy ocean.) Also, information about a macula can help us learn about the cratering process on Europa.

The macula that is targeted for E4 was picked because it looked surprisingly complex in earlier Galileo pictures of Europa taken from further away. We expect the resolution of this image to be 120 meters per pixel. If you photographed a city on earth with this resolution, you'd be able to see things as small as a football stadium.

There are many ways to look at Europa and learn something new, especially since we haven't seen it in much detail before. Much of Europa's surface is made up of large, individual plains of different types: dark plains, bright plains near the poles, and fractured plains. We can study how these are related to each other by taking pictures of large areas of Europa while we are further out, at lower resolution (about 1 km per pixel). As we get closer, we can image a small area at better resolution (0.5 km per pixel) to study each plain type in detail. Finally, when we are closest to the moon, we can look at an individual object up close with very high resolution (20 to 30 meters per pixel), and use that information to imply details about the rest of the moon. This global image of Europa from earlier Galileo flybys can give you an idea of the dark terrain we are looking at, but remember our best resolution so far is about 1 km per pixel, or 50 times less crisp than what we expect in this E4 encounter! Use your imagination on this one!

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