This picture of Zal Patera, Io is a combination of high resolution black and white images taken by NASA's Galileo spacecraft on 25 November 1999 and lower resolution color images taken by Galileo on 3 July 1999. The color mosaic was created from images taken using the camera's near-infrared, green, and violet filters (slightly more than the visible range) and has been processed to enhance more subtle color variations (see true color and false color global mosaics for comparison). The color mosaic illustrates the wide variety of materials on Io's surface, however, the illumination of the color images is poor for showing topographic shading. The higher resolution images were taken just before local sunset so long shadows enhance the topography and surface texture.
The combination allows scientists to better understand the relationships between the different surface materials and the underlying geologic structures. For example it can be seen that the edge of the caldera, marked by the black flows in the center towards the top of the picture, coincides with the edge of a plateau. Also, the red material (just above and to the right of the center of the image) is typically associated with regions where lava is erupting onto the surface. Here the red material follows the base of a mountain which may indicate that sulfurous gases are escaping along a fault associated with the formation of the mountain.
The northernmost plateau, which bounds the western edge of Zal patera, is estimated from the lengths of the shadows it casts to range from approximately 1.5 to 2 kilometers (4900 to 6600 feet) high. The mountain to the south of the caldera is up to approximately 4.6 kilometers (15,000 feet) high. And the small peak at the bottom of the picture is approximately 4.2 kilometers (14,000 feet) high.
The image is centered at 33.7 degrees north latitude and 81.9 degrees west longitude and north is to the top. The higher resolution images have a resolution of ~260 meters (or yards) per picture element and they are illuminated from the left. These images were taken on November 25, 1999 at a range of 26,000 kilometers (16,000 miles). The color images are illuminated from almost directly behind the spacecraft. The resolution of the color images is 1.3 kilometers (0.8 miles) per picture element. They were taken on July 3, 1999 at a distance of about 130,000 kilometers (81,000 miles) by the Solid State Imaging (SSI) system on NASA's Galileo spacecraft.
Image produced by: Moses Milazzo, Planetary Image Research Lab. (PIRL), Lunar and Planetary Lab. (LPL), University of Arizona
The Jet Propulsion Laboratory, Pasadena, CA manages the Galileo mission for NASA's Office of Space Science, Washington, DC. JPL is a division of the California Institute of Technology, Pasadena, CA.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at http://galileo.jpl.nasa.gov/. Background information and educational context for the images can be found at http://galileo.jpl.nasa.gov/images/io/ioimages.html.
NASA's Planetary Photojournal PIA-02527
March 6, 2000