• DOI:10.1126/science.1219381
• Corpus ID: 206540168

Dawn at Vesta: Testing the Protoplanetary Paradigm

@article{Russell2012DawnAV,
  title={Dawn at Vesta: Testing the Protoplanetary Paradigm},
  author={Christopher T. Russell and Carol A. Raymond and Angioletta Coradini and Harry Y. McSween and Maria T. Zuber and Andreas Nathues and Maria Cristina De Sanctis and Ralf Jaumann and Alex S. Konopliv and Frank Preusker and Sami W. Asmar and Ryan S. Park and R. W. Gaskell and H. Uwe Keller and Stefano Mottola and Thomas Roatsch and Jennifer E. C. Scully and D. E. Smith and Pasquale Tricarico and M. J. Toplis and Ulrich R. Christensen and William Charles Feldman and David J. Lawrence and Timothy J. Mccoy and Thomas H. Prettyman and R. C. Reedy and M. Sykes and Timothy N. Titus},
  journal={Science},
  year={2012},
  volume={336},
  pages={684 - 686}
}

• C. Russell, C. Raymond, +25 authors T. Titus
• Published 11 May 2012
• Geology, Physics
• Science

A New Dawn Since 17 July 2011, NASA's spacecraft Dawn has been orbiting the asteroid Vesta—the second most massive and the third largest asteroid in the solar system (see the cover). Russell et al. (p. 684) use Dawn's observations to confirm that Vesta is a small differentiated planetary body with an inner core, and represents a surviving proto-planet from the earliest epoch of solar system formation; Vesta is also confirmed as the source of the howardite-eucrite-diogenite (HED) meteorites. Jaumann et al. (p. 687) report on the asteroid's overall geometry and topography, based on global surface mapping. Vesta's surface is dominated by numerous impact craters and large troughs around the equatorial region. Marchi et al. (p. 690) report on Vesta's complex cratering history and constrain the age of some of its major regions based on crater counts. Schenk et al. (p. 694) describe two giant impact basins located at the asteroid's south pole. Both basins are young and excavated enough amounts of material to form the Vestoids—a group of asteroids with a composition similar to that of Vesta—and HED meteorites. De Sanctis et al. (p. 697) present the mineralogical characterization of Vesta, based on data obtained by Dawn's visual and infrared spectrometer, revealing that this asteroid underwent a complex magmatic evolution that led to a differentiated crust and mantle. The global color variations detailed by Reddy et al. (p. 700) are unlike those of any other asteroid observed so far and are also indicative of a preserved, differentiated proto-planet. Spacecraft data provide a detailed characterization of the second most massive asteroid in the solar system. The Dawn spacecraft targeted 4 Vesta, believed to be a remnant intact protoplanet from the earliest epoch of solar system formation, based on analyses of howardite-eucrite-diogenite (HED) meteorites that indicate a differentiated parent body. Dawn observations reveal a giant basin at Vesta’s south pole, whose excavation was sufficient to produce Vesta-family asteroids (Vestoids) and HED meteorites. The spatially resolved mineralogy of the surface reflects the composition of the HED meteorites, confirming the formation of Vesta’s crust by melting of a chondritic parent body. Vesta’s mass, volume, and gravitational field are consistent with a core having an average radius of 107 to 113 kilometers, indicating sufficient internal melting to segregate iron. Dawn's results confirm predictions that Vesta differentiated and support its identification as the parent body of the HEDs.