Distribution of Mid-Latitude Ground Ice on Mars from New Impact Craters
Shane Byrne,1,*
Colin M. Dundas,1
Megan R. Kennedy,2
Michael T. Mellon,3
Alfred S. McEwen,1
Selby C. Cull,4
Ingrid J. Daubar,1
David E. Shean,2
Kimberly D. Seelos,5
Scott L. Murchie,5
Bruce A. Cantor,2
Raymond E. Arvidson,4
Kenneth S. Edgett,2
Andreas Reufer,6
Nicolas Thomas,6
Tanya N. Harrison,2
Liliya V. Posiolova,2
Frank P. Seelos5
New impact craters at five sites in the martian mid-latitudes
excavated material from depths of decimeters that has a brightness
and color indicative of water ice. Near-infrared spectra of
the largest example confirm this composition, and repeated imaging
showed fading over several months, as expected for sublimating
ice. Thermal models of one site show that millimeters of sublimation
occurred during this fading period, indicating clean ice rather
than ice in soil pores. Our derived ice-table depths are consistent
with models using higher long-term average atmospheric water
vapor content than present values. Craters at most of these
sites may have excavated completely through this clean ice,
probing the ice table to previously unsampled depths of meters
and revealing substantial heterogeneity in the vertical distribution
of the ice itself.
2 Malin Space Science Systems, San Diego, CA 92191, USA.
3 Laboratory for Atmospheric and Space Physics, University of Colorado, Boulder, CO 80303, USA.
4 Department of Earth and Planetary Sciences, Washington University, St. Louis, MO 63130, USA.
5 Applied Physics Laboratory, Johns Hopkins University, Laurel, MD 20723, USA.
6 Physikalisches Institut, Universität Bern, Bern, Switzerland.
* To whom correspondence should be addressed. E-mail: shane{at}lpl.arizona.edu
