Origin, Internal Structure and Evolution of 4 Vesta

Asteroid 4 Vesta is the only preserved intact example of a large, differentiated protoplanet like those believed to be the building blocks of terrestrial planet accretion. Vesta accreted rapidly from the solar nebula in the inner asteroid belt and likely melted due to heat released due to the decay of 26Al. Analyses of meteorites from the howardite-eucrite-diogenite (HED) suite, which have been both spectroscopically and dynamically linked to Vesta, lead to a model of the asteroid with a basaltic crust that overlies a depleted peridotitic mantle and an iron core. Vesta’s crust may become more mafic with depth and might have been intruded by plutons arising from mantle melting. Constraints on the asteroid’s moments of inertia from the long-wavelength gravity field, pole position and rotation, informed by bulk composition estimates, allow tradeoffs between mantle density and core size; cores of up to half the planetary radius can be consistent with plausible mantle compositions. The asteroid’s present surface is expected to consist of widespread volcanic terrain, modified extensively by impacts that exposed the underlying crust or possibly the mantle. Hemispheric heterogeneity has been observed by poorly resolved imaging of the surface that suggests the possibility of a physiographic dichotomy as occurs on other terrestrial planets. Vesta might have had an early magma ocean but details of the early thermal structure are far from clear owing to model uncertainties and paradoxical observations from the HEDs. Petrological analysis of the eucrites coupled with thermal evolution modeling recognizes two possible mechanisms of silicate-metal differentiation leading to the formation of the basaltic achondrites: equilibrium partial melting or crystallization of residual liquid from the cooling magma ocean. A firmer understanding the plethora of complex physical and chemical processes that contribute to melting and crystallization will ultimately be required to distinguish among these possibilities. The most prominent physiographic feature on Vesta is the massive south polar basin, whose formation likely re-oriented the body axis of the asteroid’s rotation. The large impact represents the likely major mechanism of ejection of fragments that became the HEDs. Observations from the Dawn mission hold the promise of revolutionizing our understanding of 4 Vesta, and by extension, the nature of collisional, melting and differentiation processes in the nascent solar system.

[1]  Alessandro Morbidelli,et al.  Iron meteorites as remnants of planetesimals formed in the terrestrial planet region , 2006, Nature.

[2]  H. Newsom,et al.  Igneous activity in the early solar system. , 1988 .

[3]  W. Bottke,et al.  The primordial excitation and clearing of the asteroid belt—Revisited , 2006 .

[4]  Jeffrey S. Oishi,et al.  Rapid planetesimal formation in turbulent circumstellar disks , 2007, Nature.

[5]  T. Grove,et al.  High-pressure experiments on magnesian eucrite compositions - Constraints on magmatic processes in the eucrite parent body , 1991 .

[6]  S. Weidenschilling,et al.  Dust to planetesimals: Settling and coagulation in the solar nebula , 1980 .

[7]  B. Novaković,et al.  THE MASS OF (4) VESTA DERIVED FROM ITS LARGEST GRAVITATIONAL EFFECTS , 2010 .

[8]  T. Maue,et al.  The Dawn Framing Camera , 2011 .

[9]  H. Newsom Molybdenum in eucrites: evidence for a metal core in the eucrite parent body. , 1985 .

[10]  John E. Chambers,et al.  Making the Terrestrial Planets: N-Body Integrations of Planetary Embryos in Three Dimensions , 1998 .

[11]  F. Nimmo,et al.  Hf-W chronometry and the accretion and early evolution of asteroids and terrestrial planets , 2008 .

[12]  Grzegorz Michalak,et al.  Determination of Asteroid Masses , 2000 .

[13]  K. Kaneda,et al.  Thermal history of the Ibitira noncumulate eucrite as inferred from pyroxene exsolution lamella: Evidence for reheating and rapid cooling , 2001 .

[14]  Klaus Keil,et al.  Geological History of Asteroid 4 Vesta: The "Smallest Terrestrial Planet" , 2002 .

[15]  S. Chesley,et al.  Astrometric masses of 21 asteroids, and an integrated asteroid ephemeris , 2007 .

[16]  Edward R. D. Scott,et al.  Chondrules and the Protoplanetary Disk , 2011 .

[17]  Robert Q. Fugate,et al.  Full Adaptive Optics Images of Asteroids Ceres and Vesta; Rotational Poles and Triaxial Ellipsoid Dimensions☆☆☆ , 1998 .

[18]  Timothy J. McCoy,et al.  Non-chondritic meteorites from asteroidal bodies , 1998 .

[19]  M. Gaffey,et al.  Geologic Mapping of Vesta from 1994 Hubble Space Telescope Images , 1995 .

[20]  A. Dombard,et al.  Calculating the topography of a differentiated Vesta , 2009 .

[21]  G. Wetherill,et al.  Provenance of the terrestrial planets. , 1994, Geochimica et cosmochimica acta.

[22]  G. Consolmagno,et al.  Composition and evolution of the eucrite parent body - Evidence from rare earth elements. [extraterrestrial basaltic melts] , 1977 .

[23]  J. M. Champney,et al.  Particle-Gas Dynamics in the Midplane of a Protoplanetary Nebula , 1993 .

[24]  A. Fienga,et al.  INPOP08, a 4-D planetary ephemeris: from asteroid and time-scale computations to ESA Mars Express and Venus Express contributions , 2009, 0906.2860.

[25]  A. Boss,et al.  Protostars and Planets VI , 2000 .

[26]  H. Dingle,et al.  The Origin of the Solar System , 1932, Nature.

[27]  H. Takeda,et al.  Evidence for excavation of deep crustal material of a Vesta-like body from Ca compositional gradients in pyroxene , 1994 .

[28]  D. Mittlefehldt The genesis of diogenites and HED parent body petrogenesis , 1994 .

[29]  G. Lugmair,et al.  Early solar system events and timescale , 2001 .

[30]  G. Arrhenius,et al.  Aggregation of grains in space , 1973 .

[31]  H. Takeda A layered-crust model of a Howardite parent body , 1979 .

[32]  Evolutionary time scales for circumstellar disks associated with intermediate- and solar-type stars , 1993 .

[33]  Pierre Cartigny,et al.  Lead Isotopic Ages of Chondrules and Calcium-Aluminum – Rich Inclusions , 2022 .

[34]  M. Zuber,et al.  Mars high resolution gravity fields from MRO, Mars seasonal gravity, and other dynamical parameters , 2011 .

[36]  H. McSween,et al.  A Thermal Model for the Differentiation of Asteroid 4 Vesta, Based on Radiogenic Heating☆ , 1998 .

[37]  M. Drake Presidential Address: Presented 2000 August 28, Chicago, Illinois, USA The eucrite/Vesta story , 2001 .

[38]  Richard P. Binzel,et al.  Vesta: Spin Pole, Size, and Shape from HST Images , 1997 .

[39]  H. P. Rickman,et al.  Asteroids comets meteors , 1984 .

[40]  I. Franchi,et al.  Geochemistry of diogenites: Still more diversity in their parental melts , 2008 .

[41]  H. Takeda,et al.  A model for the origin of basaltic achondrites based on the Yamato 7308 Howardite , 1985 .

[42]  JOHN S. Lewis Physics And Chemistry Of The Solar System , 1995 .

[43]  H. McSween,et al.  HED Meteorites and Their Relationship to the Geology of Vesta and the Dawn Mission , 2011 .

[44]  E. Scott,et al.  Oxygen isotopic constraints on the origin and parent bodies of eucrites, diogenites, and howardites , 2009 .

[45]  H. McSween,et al.  Thermal Evolution Models of Asteroids , 2002 .

[46]  Richard P. Binzel,et al.  Asteroid-meteorite links: the Vesta conundrum(s) , 2005, Proceedings of the International Astronomical Union.

[47]  M. Gaffey,et al.  Near-IR imaging of Asteroid 4 Vesta , 2005 .

[48]  E. Asphaug,et al.  Mega‐ejecta on asteroid Vesta , 2011 .

[49]  G. Wetherill An alternative model for the formation of the asteroids , 1992 .

[50]  G. Lugmair,et al.  Chronology of asteroid accretion and differentation , 2002 .

[51]  Kevin Righter,et al.  A magma ocean on Vesta: Core formation and petrogenesis of eucrites and diogenites , 1997 .

[52]  Michael J. Gaffey,et al.  Surface Lithologic Heterogeneity of Asteroid 4 Vesta , 1997 .

[53]  F. Nimmo,et al.  Hf-W chronology of the accretion and early evolution of asteroids and terrestrial planets , 2009 .

[54]  H. Wänke,et al.  The Bulk Composition of the Eucrite Parent Asteroid and its Bearing on Planetary Evolution , 1980 .

[55]  M. Bizzarro,et al.  Chronology of the Solar System’s Oldest Solids , 2008 .

[56]  A. Nakamura,et al.  Cratering Experiments into Curved Surfaces and Their Implication for Craters on Small Satellites , 1993 .

[57]  Alessandro Rossi,et al.  Interiors of small bodies: foundations and perspectives , 2003 .

[58]  G. Lugmair,et al.  Early solar system timescales according to 53Mn-53Cr systematics , 1998 .

[59]  Daniel T. Britt,et al.  The density and porosity of meteorites from the Vatican collection , 1998 .

[60]  D. J. Tholen,et al.  The Eight-Color Asteroid Survey: Results for 589 Minor Planets , 1985 .

[61]  J. Colwell,et al.  Aerodynamical sticking of dust aggregates. , 2001, Physical review. E, Statistical, nonlinear, and soft matter physics.

[62]  Angioletta Coradini,et al.  Dawn Mission to Vesta and Ceres , 2007 .

[63]  K. Holsapple THE SCALING OF IMPACT PROCESSES IN PLANETARY SCIENCES , 1993 .

[64]  D. Davis,et al.  Accretional Evolution of a Planetesimal Swarm , 1997 .

[65]  E. Feigelson,et al.  AN IMPROVED HR DIAGRAM FOR CHAMAELEON I PRE-MAIN-SEQUENCE STARS , 1996 .

[66]  S. Beckwith,et al.  A Survey for Circumstellar Disks around Young Stellar Objects , 1990 .

[67]  Meenakshi Wadhwa,et al.  The age of the Solar System redefined by the oldest Pb–Pb age of a meteoritic inclusion , 2010 .

[68]  A. Halliday Timing, mechanisms and conditions of terrestrial planet accretion and early differentiation , 2005 .

[69]  Dah-Ning Yuan,et al.  A global solution for the Mars static and seasonal gravity, Mars orientation, Phobos and Deimos masses, and Mars ephemeris , 2006 .

[70]  J. Delaney,et al.  A model composition of the basaltic achondrite planetoid , 1997 .

[71]  J. Longhi,et al.  Phase equilibrium constraints on the howardite-eucrite-diogenite association , 1988 .

[72]  E. Maroon,et al.  Magma Ocean Solidification Processes on Vesta , 2008 .

[73]  John S. Hendricks,et al.  Dawn’s Gamma Ray and Neutron Detector , 2011 .

[74]  A. Bini,et al.  The VIR Spectrometer , 2011 .

[75]  Paul H. Warren,et al.  THE MAGMA OCEAN CONCEPT AND LUNAR EVOLUTION , 1985 .

[76]  K. Keil,et al.  Protostars and Planets V , 2007 .

[77]  G. Michalak,et al.  Determination of asteroid masses , 2000 .

[78]  Donald W. McCarthy,et al.  High Resolution Images of Vesta at 1.65 μm , 1994 .

[79]  E. Pitjeva High-Precision Ephemerides of Planets—EPM and Determination of Some Astronomical Constants , 2005 .

[80]  Harry Y. McSween,et al.  Meteorites and the early solar system II , 2006 .

[81]  E. Stolper Petrogenesis of eucrite, howardite and diogenite meteorites , 1975, Nature.

[82]  Brigitte Zanda,et al.  Relative chronology of crust formation on asteroid Vesta: Insights from the geochemistry of diogenites , 2010 .

[83]  Eiichiro Kokubo,et al.  Oligarchic growth of protoplanets , 1996 .

[84]  David E. Smith,et al.  The Dawn Gravity Investigation at Vesta and Ceres , 2011 .

[85]  L. Hartmann,et al.  Accretion processes in star formation , 1999 .

[86]  L. Taylor,et al.  Vesta as the howardite, eucrite and diogenite parent body: Implications for the size of a core and for large‐scale differentiation , 1997 .

[87]  Floris van Liere Planet Formation , 2009 .

[88]  Richard P. Binzel,et al.  Vesta, Vestoids, and the howardite, eucrite, diogenite group: Relationships and the origin of spectral differences , 2001 .

[89]  T. Guillot,et al.  Formation of planetesimals in the Solar Nebula , 2001 .

[90]  S. Weidenschilling,et al.  Formation of planetesimals in the solar nebula , 1993 .

[91]  T V Johnson,et al.  Asteroid Vesta: Spectral Reflectivity and Compositional Implications , 1970, Science.

[92]  S. S. Russell,et al.  Timescales of Accretion and Differentiation in the Early Solar System: the Meteoritic Evidence , 2000 .

[93]  S. Sahijpal,et al.  Differentiation of Vesta and the parent bodies of other achondrites , 2010 .

[94]  R. Millis,et al.  Direct determination of asteroid diameters from occultation observations , 1979 .

[95]  M. Domeneghetti,et al.  Cooling rates of diogenites: A study of Fe2+‐Mg ordering in orthopyroxene by single‐crystal x‐ray diffraction , 1997 .

[96]  A. Boss TEMPERATURES IN PROTOPLANETARY DISKS , 1998 .

[97]  Richard P. Binzel,et al.  Impact excavation on Asteroid 4 Vesta: Hubble Space Telescope results , 1997 .

[98]  L. E. Bowman,et al.  Automated energy dispersive spectrometer modal analysis applied to the diogenites , 1997 .

[99]  K. Righter,et al.  Core Formation in Earth's Moon, Mars, and Vesta , 1996 .

[100]  John H. Jones The composition of the mantle of the eucrite parent body and the origin of eucrites , 1984 .

[101]  W. Hartmann Planet formation - Mechanism of early growth , 1978 .

[102]  A. Boss,et al.  The Early Evolution of the Inner Solar System: A Meteoritic Perspective , 2001, Science.

[103]  A. Halliday,et al.  Tungsten isotopes and the early development of the Earth and Moon , 1999 .

[104]  A. Jambon,et al.  Widespread magma oceans on asteroidal bodies in the early Solar System , 2005, Nature.

[105]  Elizabeth A. Lada,et al.  Disk Frequencies and Lifetimes in Young Clusters , 2001, astro-ph/0104347.

[106]  E. Stolper Experimental petrology of eucritic meteorites , 1977 .

[107]  J. Chambers Planetary accretion in the inner Solar System , 2004 .

[108]  H. Mori,et al.  Mineralogical Comparison of Antarctic and Non-Antarctic HED (Howardites-Eucrites-Diogenites) Achondrites. , 1983 .

[109]  J. Lunine,et al.  Protostars and planets III , 1993 .

[110]  J. Miller,et al.  A Global Solution for the Gravity Field, Rotation, Landmarks, and Ephemeris of Eros , 2002 .

[111]  Mark J. McCaughrean,et al.  Direct Imaging of Circumstellar Disks in the Orion Nebula , 1996 .

[112]  J. Tsuchiya,et al.  Phase transition in MgSiO 3 perovskite in the earth's lower mantle , 2004 .

[113]  A. W. Beck,et al.  Diogenites as polymict breccias composed of orthopyroxenite and harzburgite , 2010 .

[114]  E. Anders,et al.  Meteorites and the Early Solar System , 1971 .

[115]  G. Wetherill Origin of the asteroid belt. , 1989 .

[116]  G. Kallemeyn,et al.  Siderophile and other geochemical constraints on mixing relationships among HED-meteoritic breccias , 2009 .

[117]  R. Binzel,et al.  Chips off of Asteroid 4 Vesta: Evidence for the Parent Body of Basaltic Achondrite Meteorites , 1993, Science.