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AGU: Geophysical Research Letters



  • Moon
  • ice
  • water

Index Terms

  • 5420 - Impact phenomena, cratering
  • 5422 - Ices
  • 5464 - Remote sensing
  • 5470 - Surface materials and properties
  • 6250 - Moon

Paper in Press


An upper limit for ice in Shackleton crater as revealed by LRO Mini-RF orbital radar

Key Points
  • An upper bound on the amount of ice in this crater is ~5 wt%.
  • Radar data has been obtained for all of Shackleton, a first.
  • No evidence for thick, meters-thick ice is found.


Bradley Thomson

D. Benjamin J. Bussey

Catherine Dorothy Neish

Joshua T.S. Cahill

Essam Heggy

Randolph Livingstone Kirk

G. Wesley Patterson

R. Keith Raney

Paul D. Spudis

Thomas William Thompson

Eugene Ustinov

Although diverse measurements have indicated H+, OH-, or H2O species in the lunar polar regions, pinpointing its location, form, and abundance in specific reservoirs has proven elusive. Here we report on the first orbital radar measurements of Shackleton crater near the lunar south pole. Mini-RF observations indicate a patchy, heterogeneous enhancement in CPR (circular polarization ratio) on the crater walls whose strength decreases with depth toward the crater floor, a result that is most consistent with a roughness effect due to less mature regolith present on the crater wall slopes. However, the results do not rule out a modest ice contribution, and an upper limit of ~5-10 wt% H2O ice (up to 30 vol. %) present in the uppermost meter of regolith is also consistent with the observations.

Received 23 April 2012; accepted 16 June 2012.

Citation: Thomson, B., et al. (2012), An upper limit for ice in Shackleton crater as revealed by LRO Mini-RF orbital radar, Geophys. Res. Lett., doi:10.1029/2012GL052119, in press.