Overview of Spirit Microscopic Imager Results

Ken E. Herkenhoff, Steve W. Squyres, Raymond E. Arvidson, Shoshanna B. Cole, Rob Sullivan, Aileen Yingst, Nathalie Cabrol, Ella M. Lee, Janet Richie, Bob Sucharski, James F. Bell, Fred Calef, Mary Chapman, Lauren Edgar, Brenda Franklin, Paul Geissler, Joel Hurowitz, Elsa Jensen, Jeffrey R. Johnson, Randy KirkPeter Lanagan, Craig Leff, Justin Maki, Kevin Mullins, Bonnie Redding, Melissa Rice, Michael Sims, Larry Soderblom, Nicole Spanovich, Richard Springer, Annette Sunda, Alicia Vaughan

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


This paper provides an overview of Mars Exploration Rover Spirit Microscopic Imager (MI) operations and the calibration, processing, and analysis of MI data. The focus of this overview is on the last five Earth years (2005–2010) of Spirit's mission in Gusev crater, supplementing the previous overview of the first 450 sols of the Spirit MI investigation. Updates to radiometric calibration using in-flight data and improvements in high-level processing are summarized. Released data products are described, and a table of MI observations, including target/feature names and associated data sets, is appended. The MI observed natural and disturbed exposures of rocks and soils as well as magnets and other rover hardware. These hand-lens-scale observations have provided key constraints on interpretations of the formation and geologic history of features, rocks, and soils examined by Spirit. MI images complement observations by other Spirit instruments, and together show that impact and volcanic processes have dominated the origin and evolution of the rocks in Gusev crater, with aqueous activity indicated by the presence of silica-rich rocks and sulfate-rich soils. The textures of some of the silica-rich rocks are similar to terrestrial hot spring deposits, and observations of subsurface cemented layers indicate recent aqueous mobilization of sulfates in places. Wind action has recently modified soils and abraded many of the rocks imaged by the MI, as observed at other Mars landing sites.

Original languageEnglish (US)
Pages (from-to)528-584
Number of pages57
JournalJournal of Geophysical Research: Planets
Issue number2
StatePublished - Feb 2019


  • MER
  • Mars
  • Microscopic Imager
  • Spirit
  • geology

ASJC Scopus subject areas

  • Geochemistry and Petrology
  • Geophysics
  • Earth and Planetary Sciences (miscellaneous)
  • Space and Planetary Science


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