MARS DUST DEVILS: ANALYSIS TECHNIQUES FOR MARS EXPLORATION ROVER DATA, SPIRIT

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MARS DUST DEVILS ANALYSIS TECHNIQUES FOR MARS
EXPLORATION ROVER DATA, SPIRIT

• Shane Thompson, Ron Greeley, Patrick Whelley,
  Lynn Neakrase, Danny Foley, Mark Lemmon
• and the Athena Science Team
• Dust Devil Workshop, USGS Flagstaff, Arizona
• 20 September 2005

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DUST DEVILS ON MARS

• PREVIOUSLY
• 118 vortices inferred by both Viking spacecraft
  atmospheric instruments (Ryan and Lucich, 1983)
• Mars Pathfinder saw 79 vortices in 83 sol mission
  with ASI/MET package and 14 in images, mostly in
  Gallery Panorama

• GUSEV
• Spirit has observed dust devils since sol 421 (Ls
  173)
• Ongoing rover operations collect systematic data
  to obtain measurements of diameters, dust
  opacities, viewing distances as well as seasonal
  trends
• 240 dust devils seen in first 100 sols of dust
  devil season

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IMAGING TECHNIQUES

• PATHFINDER
• Utilized color filter subtraction of horizon/sky
  images from panorama acquisitions
• Red minus blue thought to be best method

• SPIRIT
• Initially took red-blue approach with Pancam --
  caught some but not useful
• Developed Navcam movie
• - surprisingly helpful

Spirits advantage is the oblique viewing geometry
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VIEW FROM THE HILLS

• Through the first 100 sols, Spirit was 60 m
  above the plains within the Columbia Hills
• Allows observing greater contrast between dust
  devil and surface
• MOC images allowed for reliable surface location
  mapping
• Ellipse placed for likely zone of occurrence
• With pixel size of dust devil in image and
  min/max possible distance
• ? diameters ? load flux
• Pixel intensities can be used to calculate
  individual dust opacities

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RESULTS