SHARAD soundings and surface roughness at past, present, and proposed landing sites on Mars: Reflections at Phoenix may be attributable to deep ground ice

Nathaniel E. Putzig, Roger J. Phillips, Bruce A. Campbell, Michael T. Mellon, John W. Holt, T. Charles Brothers

Research output: Contribution to journalArticle

23 Scopus citations


We use the Shallow Radar (SHARAD) on the Mars Reconnaissance Orbiter to search for subsurface interfaces and characterize surface roughness at the landing sites of Viking Landers 1 and 2, Mars Pathfinder, the Mars Exploration Rovers Spirit and Opportunity, the Phoenix Mars lander, the Mars Science Laboratory Curiosity rover, and three other sites proposed for Curiosity. Only at the Phoenix site do we find clear evidence of subsurface radar returns, mapping out an interface that may be the base of ground ice at depths of ~15-66 m across 2900 km2 in the depression where the lander resides. At the Opportunity, Spirit, and candidate Curiosity sites, images and altimetry show layered materials tens to hundreds of meters thick extending tens to hundreds of kilometers laterally. These scales are well within SHARAD's resolution limits, so the lack of detections is attributable either to low density contrasts in layers of similar composition and internal structure or to signal attenuation within the shallowest layers. At each site, we use the radar return power to estimate surface roughness at scales of 10-100 m, a measure that is important for assessing physical properties, landing safety, and site trafficability. The strongest returns are found at the Opportunity site, indicating that Meridiani Planum is exceptionally smooth. Returns of moderate strength at the Spirit site reflect roughness more typical of Mars. Gale crater, Curiosity's ultimate destination, is the smoothest of the four proposed sites we examined, with Holden crater, Eberswalde crater, and Mawrth Vallis exhibiting progressively greater roughness. Key Points Possible base of ground ice is mapped with Shallow Radar at Phoenix Mars siteRoughness at scales of 10 to 100 m is assessed at 10 landing sites on MarsHigh-resolution surface-elevation models are critical for radar interpretation

Original languageEnglish (US)
Pages (from-to)1936-1949
Number of pages14
JournalJournal of Geophysical Research E: Planets
Issue number8
StatePublished - Aug 2014


  • Shallow Radar
  • ground ice
  • radar sounding
  • spacecraft landing sites
  • surface roughness

ASJC Scopus subject areas

  • Geophysics
  • Forestry
  • Oceanography
  • Aquatic Science
  • Ecology
  • Water Science and Technology
  • Soil Science
  • Geochemistry and Petrology
  • Earth-Surface Processes
  • Atmospheric Science
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science
  • Palaeontology

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