This colored animation of Vesta is made from a mosaic of Dawn Framing Camera (FC) color composite images wrapped around the shape model of Vesta. The shape model is a 3-D representation of the topography of Vesta, which is calculated from images observed from different viewing angles. The FC has 7 color filters that allow it to image Vesta in a number of different wavelengths of light. In this case we are interested in filter 2, which images Vesta at 440 nm, filter 5, which images Vesta at 750 nm and filter 7, which images Vesta at 920 nm. Nm stands for nanometers and is a measure of the wavelength of light. Being able to image in many wavelengths enhances features and colors that would otherwise be indistinguishable to the human eye. The mosaic shows a RGB color composite view of Vesta. In an RGB image the colors red, green and blue each display a specific characteristic and are stacked together to form one image. In this case red represents the ratio of the brightness at a wavelength of 750 nm to the brightness at 440 nm; green is used for the ratio of the brightness at 750 nm to 920 nm and blue is used for the ratio of the brightness at 440 nm to 750 nm. These ratios have all been picked for specific scientific purposes. The green shows the relative strength of a particular mineralogical characteristic, the ferrous absorption band, at 1000 nm so that a brighter green color signifies a higher relative strength of this band. The blending between the red and blue heightens the color range of visible light. The animation begins overlooking Vesta’s north pole. This region is gray in color because it has not yet been imaged by Dawn. It is clear from the wide range of colors that Vesta is a very diverse asteroid. A number of areas of ejecta show a strong red-orange color and the Rheasilvia impact basin, in the southern hemisphere, has a strong greenish color. The Rheasilvia impact basin is a region of strong ferrous absorption band material because green shows the relative strength of the ferrous absorption band.
NASA’s Dawn spacecraft obtained these images with its framing camera in September and October 2011. The images were taken through the camera’s clear filter. The distance to the surface of Vesta is around 700 kilometers (435 miles) on average and the images have an average resolution of about 70 meters (230 feet) per pixel. These images were acquired during the HAMO (high-altitude mapping orbit) phase of the mission. The shape model was made by Robert Gaskell (PSI) and the animation was made by Dave O’Brien (PSI).
The Dawn mission to Vesta and Ceres is managed by NASA’s Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, for NASA’s Science Mission Directorate, Washington D.C. UCLA is responsible for overall Dawn mission science. The Dawn framing cameras have been developed and built under the leadership of the Max Planck Institute for Solar System Research, Katlenburg-Lindau, Germany, with significant contributions by DLR German Aerospace Center, Institute of Planetary Research, Berlin, and in coordination with the Institute of Computer and Communication Network Engineering, Braunschweig. The Framing Camera project is funded by the Max Planck Society, DLR, and NASA/JPL.
More information about Dawn is online at http://dawn.jpl.nasa.gov.
Image credit: NASA/JPL-Caltech/UCLA/MPS/DLR/IDA