The world gets a new look at Jupiter's icy moon as NASA releases a remastered image of Europa using photos captured by the Galileo spacecraft in the 1990s. The images show the moon's largest portion at the best possible resolution.
A previous version of the image shows Europa in mosaic view. While the image showed strongly enhanced colors, it was in lower resolution so some of the details of the moon are not visible. To remaster the image, NASA assembled the photos Galileo took, creating a realistic view of Europa's surface that approximates how the moon would look like to the naked eye.
Photos captured using violet, green and near-infrared filters were combined and corrected to fix scattered light outside the image. Color correction was guided by wavelength calibration. For gaps in the old images, they were filled using simulated color based on the colors nearby surface areas have, when they are of similar types of terrain.
The result was an image that highlights the diversity in the moon's surface geology, featuring long, linear ridges and cracks crisscrossing through the surface, punctuated by swaths of disrupted terrain where Europa's surface ice crust broke and re-froze into new patterns.
Variations in color across the moon's surface are due to differences in location and the type of geologic feature. For instance, areas appearing white or blue contain pure water ice, while those that are brownish and reddish include higher concentrations of non-ice components.
Europa's polar regions are also visible in the left and right sides of the remastered image, appearing noticeably bluer compare to equatorial regions of the moon that look whiter. This variation in color is believed to be brought about by differences in the grain sizes of ice in the two locations.
The Galileo mission was managed by the Jet Propulsion Laboratory for NASA's Science Mission Directorate. The photos used for the remastered image were taken by the spacecraft during its first and fourteenth orbits around Jupiter's system back in 1995 and 1998, respectively. Using the Galileo Solid-State Imaging experiment, the spacecraft captured images at a scale of 2 miles per pixel.
In 2003, Galileo plunged into Jupiter's atmosphere, crushing the spacecraft. It was destroyed deliberately to protect one of its very own discoveries -- a possible ocean underneath Europa's icy crust. As the first to observe Jupiter and its moons, it discovered subsurface saltwater not only on Europa but on Callisto and Ganymede as well, and highlighted Io's intense volcanic activity.
