Cratering Rates in the Outer Solar System

We have constructed a self-consistent study of cratering rates in the outer solar system. Two papers were written, one on cratering asymmetries on synchronously rotating satellites and the other on the cratering rates themselves. The first addresses the well-founded expectation that the leading hemisphere of a synchronously rotating satellite should be more heavily cratered than the trailing hemisphere, and how our solar system has avoided showing much sign of this. We conclude that Ganymede has in the past rotated nonsynchronously, which may imply that it once harboured a thicker inner ocean than it does now. The other study began as an attempt to determine the age of the surface of Europa at a time when Europa was regarded as a major Exobiological target. In keeping with changing times the study expanded to the point that it now recommends cratering rates for worlds as diverse as Charon and Pluto, and includes the contributions of several invaluable co-authors, none of whom would agree with all of my conclusions. The nexus of the work is the size-frequency distribution of comets striking Jupiter (Figure). This was determined using the historically observed record of comets striking or nearly striking Jupiter; the size-frequency distributions of craters on lightly cratered surfaces of Europa, Ganymede, and Triton; and the size-frequncy distribution of Kuiper Belt objects. Extreme reductionists will be happy to know that the surface of Europa probably has an age of around 50 million years. Perhaps more intriguing is that Neptune's moon Triton, by origin a giant comet and by capture and orbital evolution a once fully melted giant comet, has a surface that is probably no older than Europa's.

[1]  K. Zahnle,et al.  Cratering rates on the Galilean satellites. , 1998, Icarus.

[2]  P. Schenk.  Ganymede and Callisto - Complex crater formation and planetary crusts , 1991 .

[3]  Paul M. Schenk,et al.  Crater formation and modification on the icy satellites of Uranus and Saturn: Depth/diameter and central peak occurrence , 1989 .

[4]  G. Neukum,et al.  Cratering rate over the surface of a synchronous satellite , 1984 .

[5]  K. Zahnle.  The Collision of Comet Shoemaker-Levy 9 and Jupiter: Dynamics and chemistry of SL9 plumes , 1996 .

[6]  D. C. Jewitt,et al.  Population and Size Distribution of Small Jovian Trojan Asteroids , 2000, astro-ph/0004117.

[7]  L. Dones,et al.  Capture Statistics of Short-Period Comets: Implications for Comet D/Shoemaker–Levy 9 , 1996 .

[8]  A. Fitzsimmons,et al.  CCD photometry of distant comets II , 2001 .

[9]  David P. Hamilton,et al.  Origin of Saturn's E Ring: Self-Sustained, Naturally , 1994, Science.

[10]  R. H. Brown,et al.  Voyager 2 in the Uranian System: Imaging Science Results , 1986, Science.

[11]  Jeffrey S. Kargel,et al.  The geology of Triton. , 1995 .

[12]  J. S. Dohnanyi.  Interplanetary objects in review: Statistics of their masses and dynamics , 1972 .

[13]  Harold F. Levison,et al.  From the Kuiper Belt to Jupiter-Family Comets: The Spatial Distribution of Ecliptic Comets☆ , 1997 .

[14]  J. Rahe,et al.  Properties of Cometary Nuclei , 1994 .

[15]  G. Kronk.  Comets: A Descriptive Catalog , 1984 .

[16]  C. Chapman,et al.  Cratering of planetary satellites. , 1986 .

[17]  C. F. Yoder,et al.  New observations of Saturn's coorbital satellites , 1992 .

[18]  D. Williams,et al.  Size Distribution of Collisionally Evolved Asteroidal Populations: Analytical Solution for Self-Similar Collision Cascades , 1994 .

[19]  J. Plescia.  Geological terrains and crater frequencies on Ariel , 1987, Nature.

[20]  D. Hughes.  Cometary magnitude distribution and the ratio between the numbers of long- and short-period comets , 1988 .

[21]  H. Melosh,et al.  Estimate of the size of comet Shoemaker-Levy 9 from a tidal breakup model , 1993, Nature.

[22]  Alessandro Morbidelli,et al.  The Structure of the Kuiper Belt: Size Distribution and Radial Extent , 2001 .

[23]  L. Esposito,et al.  Fragmentation rates of small satellites in the outer solar system , 2000 .

[24]  J. Plescia.  Cratering history of the Uranian satellites: Umbriel, Titania, and Oberon , 1987 .

[25]  M. Duncan,et al.  A disk of scattered icy objects and the origin of Jupiter-family comets. , 1997, Science.

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

[27]  R. L. Newburn,et al.  Comets in the post-Halley era , 1991 .

[28]  G. Danielson,et al.  Saturn's E ring: I. CCD observations of March 1980 , 1981 .

[29]  E. Shoemaker,et al.  The Flux of Periodic Comets Near Earth , 1993 .

[30]  J. Head,et al.  IMPACT CRATERING - A Geological Process on the Planets , 1981 .

[31]  J. L. Mitchell,et al.  A New Look at the Saturn System: The Voyager 2 Images , 1982, Science.

[32]  David J. Tholen,et al.  Pluto and Charon , 1997 .

[33]  T V Johnson,et al.  Encounter with saturn: voyager 1 imaging science results. , 1981, Science.

[34]  E. Shoemaker,et al.  Cratering Time Scales for the Galilean Satellites , 1982 .

[35]  S. Tremaine,et al.  The Origin of Short-Period Comets , 1988 .

[36]  D. Stevenson.  Mars' core and magnetism , 2001, Nature.

[37]  H. Rickman,et al.  A catalog of observed nuclear magnitudes of Jupiter family comets , 2000 .

[38]  Harold F. Levison,et al.  The Population of the Trans-Neptunian Region , 1993 .

[39]  Edgar Everhart,et al.  Intrinsic Distributions of Cometary Perihelia and Magnitudes , 1967 .

[40]  Jeffrey S. Kargel,et al.  Neptune and triton , 1997 .

[41]  M. Ashley,et al.  A Wide-Field CCD Survey For Centaurs and Kuiper Belt Objects , 2000 .

[42]  E. M. Shoemaker,et al.  Trojan asteroids - Populations, dynamical structure and origin of the L4 and L5 swarms , 1989 .

[43]  Harold F. Levison,et al.  Differential Cratering of Synchronously Rotating Satellites by Ecliptic Comets , 2001 .

[44]  Collisional Probability of Periodic Comets with the Terrestrial Planets: An Invalid Case of Analytic Formulation , 1998 .

[45]  Kevin R. Housen,et al.  Some recent advances in the scaling of impact and explosion cratering , 1987 .

[46]  Chadwick A. Trujillo,et al.  Properties of the Trans-Neptunian Belt: Statistics from the Canada-France-Hawaii Telescope Survey , 2001 .

[47]  Erik Asphaug,et al.  Structure of Comet Shoemaker-Levy 9 Inferred from the Physics of Tidal Breakup , 1996 .

[48]  R. Greeley,et al.  Geology of Lofn Crater, Callisto , 2001 .

[49]  Harold F. Levison,et al.  The formation of Uranus and Neptune in the Jupiter–Saturn region of the Solar System , 1999, Nature.

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

[51]  S. K. Croft,et al.  Voyager 2 at Neptune: Imaging Science Results , 1989, Science.

[52]  Renu Malhotra,et al.  Tidal evolution into the Laplace resonance and the resurfacing of Ganymede , 1997 .

[53]  S. Squyres,et al.  Bombardment history of the Saturn system , 1985 .

[54]  M. S. Matthews,et al.  Planetary Science. (Book Reviews: Origin and Evolution of Planetary and Satellite Atmospheres) , 1989 .

[55]  Satoshi Inaba,et al.  Steady-State Size Distribution for the Self-Similar Collision Cascade , 1996 .

[56]  D. Davis,et al.  Modelling the disruption and reaccumulation of Miranda , 1998 .

[57]  Ľ. Kresák,et al.  The intrinsic number density of active long-period comets in the inner solar system , 1978 .

[58]  V. Safronov,et al.  Evolution of the protoplanetary cloud and formation of the earth and the planets , 1972 .

[59]  The Evolution of Long-Period Comets , 1997, astro-ph/9705153.

[60]  S. Stern.  Collisional Time Scales in the Kuiper Disk and Their Implications , 1995 .

[61]  S. K. Croft,et al.  The Impact Cratering Record on Triton , 1990, Science.

[62]  K. Housen,et al.  Cratering of the Uranian satellites , 1991 .

[63]  M. S. Matthews,et al.  Hazards Due to Comets and Asteroids , 1992 .

[64]  E. Shoemaker,et al.  Dynamical evolution of Jupiter's Trojan asteroids , 1997, Nature.

[65]  J. Rogers,et al.  The giant planet Jupiter , 1995 .

[66]  Sylvio Ferraz-Mello,et al.  Close Approaches of Trans-Neptunian Objects to Pluto Have Left Observable Signatures on Their Orbital Distribution , 1999 .

[67]  Jack Wisdom,et al.  Dynamical Stability in the Outer Solar System and the Delivery of Short Period Comets , 1993 .

[68]  Daniel D. Durda,et al.  Collision Rates in the Present-Day Kuiper Belt and Centaur Regions: Applications to Surface Activation and Modification on Comets, Kuiper Belt Objects, Centaurs, and Pluto–Charon , 1999, astro-ph/9912400.

[69]  M. Holman,et al.  Planetary Impact Rates from Ecliptic Comets , 2000 .

[70]  Paul R. Weissman,et al.  The impactor flux in the Pluto-Charon system , 1993 .

[71]  P. Nicholson,et al.  HST Observations of Saturnian Satellites during the 1995 Ring Plane Crossings , 2001 .

[72]  H. Rickman,et al.  The population, magnitudes, and sizes of Jupiter family comets , 1999 .

[73]  D. K. Yeomans,et al.  Orbital motion, nucleus precession, and splitting of periodic Comet Brooks 2 , 1985 .

[74]  E. Lellouch,et al.  Carbon monoxide in Jupiter after the impact of comet Shoemaker-Levy 9 , 1997 .

[75]  W. McKinnon,et al.  Triton’s Surface Age and Impactor Population Revisited in Light of Kuiper Belt Fluxes: Evidence for Small Kuiper Belt Objects and Recent Geological Activity , 1999, astro-ph/9910435.

[76]  S. Synnott,et al.  Orbits and masses of Saturn's co-orbiting satellites, Janus and Epimetheus , 1989 .

[77]  M. Bailey,et al.  Hazards due to giant comets: climate and short-term catastrophism , 1995 .

[78]  P. Weissman.  Dynamical History of the Oort Cloud , 1979 .

[79]  David Morrison,et al.  Satellites of Jupiter , 1982 .

[80]  R. Strom.  The solar system cratering record: Voyager 2 results at Uranus and implications for the origin of impacting objects , 1987 .