The giant asteroid Vesta appears as a rainbow-colored palette in a new mosaic of images obtained by NASA’s Dawn spacecraft in orbit around the protoplanet.
Vesta is unique among asteroids visited by spacecraft to date in having such wide variation, supporting the notion that it is transitional between the terrestrial planets — like Earth, Mercury, Mars and Venus — and its asteroid siblings.
The false colors assigned relative to wavelength signatures from various areas, show different rock or mineral types, and reveal Vesta to be a world of many varied, well-separated layers and ingredients.
For example green shows the relative strength of a particular mineralogical characteristic, the ferrous absorption band, at 1000nm. The blending between the red and blue heightens the color range of visible light.
The Jet Propulsion Laboratory spacecraft, launched in September 2007 and arrived at Vesta on July 15, 2011. Following a year at Vesta, the spacecraft will depart in July 2012 for the dwarf planet Ceres, where it will arrive in 2015.
In images from Dawn’s framing camera, the colors reveal differences in the rock composition associated with material ejected by impacts and geologic processes, such as slumping, which have modified the asteroid’s surface.
Images from the visible and infrared mapping spectrometer reveal that the surface materials indeed contain the iron-bearing mineral pyroxene and are a mixture of rapidly cooled surface rocks and a deeper layer that cooled more slowly.
The relative amounts of the different materials mimic the topographic variations derived from stereo camera images, indicating a layered structure that has been excavated by impacts. The rugged surface of Vesta is prone to slumping of debris on steep slopes.
Dawn scientists presented the new image at the American Geophysical Union meeting in San Francisco on Monday, Dec. 5.
“Vesta’s iron core makes it special and more like terrestrial planets than a garden-variety asteroid,” said Carol Raymond, Dawn’s deputy principal investigator at JPL. “The distinct compositional variation and layering that we see at Vesta appear to derive from internal melting of the body shortly after formation, which separated Vesta into crust, mantle and core,” she concluded.