This image shows the location of one of the highest spatial resolution NIMS images acquired. The left image is an airbrush map of the surface of Ganymede from Voyager data. The small square shows the location of Antum crater, target of the high-resolution NIMS image on the right. NIMS spatial resolution is approximately 4 km/pixel and the image is a falsely colored albedo for a single wavelength near 0.8 micrometers.
Antum is what is known as a dark ray crater, that is, dark lines emanate from the central bright area. This NIMS image is a close-up of the central area and the dark rays are off the edges of the image. Dark ray craters are fairly unusual and are concentrated in one area of Ganymede's surface. They are thought to be composed of material from the body that impacted Ganymede and created the crater, rather than material brought up from the subsurface. Analysis of the NIMS data will yield compositional and mineralogical information on the dark material. This can help us to understand the nature of bodies that "crash" into the Jupiter system, as did Comet Shoemaker-Levy 9 in 1995, as well as give more information on the history of surface modification on Ganymede.
The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.
This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://www.jpl.nasa.gov/galileo/sepo.