Present-Day Impact Cratering Rate and Contemporary Gully Activity on Mars

The Mars Global Surveyor Mars Orbiter Camera has acquired data that establish the present-day impact cratering rate and document new deposits formed by downslope movement of material in mid-latitude gullies on Mars. Twenty impacts created craters 2 to 150 meters in diameter within an area of 21.5 × 106 square kilometers between May 1999 and March 2006. The values predicted by models that scale the lunar cratering rate to Mars are close to the observed rate, implying that surfaces devoid of craters are truly young and that as yet unrecognized processes of denudation must be operating. The new gully deposits, formed since August 1999, are light toned and exhibit attributes expected from emplacement aided by a fluid with the properties of liquid water: relatively long, extended, digitate distal and marginal branches, diversion around obstacles, and low relief. The observations suggest that liquid water flowed on the surface of Mars during the past decade.

[1]  Kirk,et al.  Collisionally processed rocks on mars , 1999, Science.

[2]  Z. Ceplecha.  Interactions of large meteoroids and small interplanetary bodies with the Earth's atmosphere: Theories and observational constraints , 1995 .

[3]  M. Malin,et al.  Mars Observer camera , 1992 .

[4]  Randolph L. Kirk,et al.  The rayed crater Zunil and interpretations of small impact craters on Mars , 2005 .

[5]  M. A. Caplinger,et al.  Mars Orbiter Camera geodesy campaign , 2001 .

[6]  Jennifer Lynne Heldmann,et al.  Observations of martian gullies and constraints on potential formation mechanisms , 2004 .

[7]  M. Gilmore,et al.  Role of aquicludes in formation of Martian gullies , 2002 .

[8]  A. Treiman.  Geologic settings of Martian gullies: Implications for their origins , 2003 .

[9]  Alfred S. McEwen,et al.  THE IMPORTANCE OF SECONDARY CRATERING TO AGE CONSTRAINTS ON PLANETARY SURFACES , 2006 .

[10]  M. Malin,et al.  Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission , 2001 .

[11]  F. Forget,et al.  Formation of Recent Martian Debris Flows by Melting of Near-Surface Ground Ice at High Obliquity , 2001, Science.

[12]  Donald E. Gault,et al.  Saturation and Equilibrium Conditions for Impact Cratering on the Lunar Surface: Criteria and Implications , 1970 .

[13]  Nick Hoffman,et al.  Active polar gullies on Mars and the role of carbon dioxide. , 2002, Astrobiology.

[14]  William K. Hartmann,et al.  Martian cratering 8: Isochron refinement and the chronology of Mars , 2005 .

[15]  E. Gaidos.  Cryovolcanism and the Recent Flow of Liquid Water on Mars , 2001 .

[16]  P. Christensen.  Formation of recent martian gullies through melting of extensive water-rich snow deposits , 2003, Nature.

[17]  W. Hartmann.  Martian cratering VI: Crater count isochrons and evidence for recent volcanism from Mars Global Surveyor , 1999 .

[18]  William K. Hartmann,et al.  Bolides in the present and past martian atmosphere and effects on cratering processes , 2003 .

[19]  Kenneth S. Edgett,et al.  Mass movement slope streaks imaged by the Mars Orbiter Camera , 2001 .

[20]  J. Borovička,et al.  Atmospheric fragmentation of meteoroids , 1993 .

[21]  William K. Hartmann,et al.  Cratering Chronology and the Evolution of Mars , 2001 .

[22]  H. Melosh,et al.  Effects of atmospheric breakup on crater field formation , 1980 .

[23]  Christopher P. McKay,et al.  Formation of Martian Gullies by the Action of Liquid Water Flowing Under Current Martian Environmental Conditions , 2005 .

[24]  M. Mellon,et al.  Recent gullies on Mars and the source of liquid water , 2001 .

[25]  M. Malin,et al.  Evidence for recent groundwater seepage and surface runoff on Mars. , 2000, Science.

[26]  M. Malin,et al.  Sedimentary rocks of early Mars. , 2000, Science.

[27]  Jonathan I. Lunine,et al.  Liquid CO2 breakout and the formation of recent small gullies on Mars , 2001 .