Seasonal and Daily Changes on Mars

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Seasonal and Daily Changes on Mars

• Global and local dust storms
• Dust devils
• Eroded rock and dunes
• Polar Caps and their variation by season
• Layers within caps
• Other cold-climate features
• Cause of climate changes on Mars?

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Global dust storms evolve in lt 1 months, and last
gt 3 months
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Dust Storms
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Dust storm
Polar cap
Dust storm
Africa
Local dust storm on Mars
Dust storm from Sahara
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Dust devil tracks evidence for local winds and
surface fines
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Wind-scoured rocks are called Yardangs
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The material eroded from rocks forms many
dunes. Show constant wind direction for long
periods of time.
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Wind erosion features on Mars
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North Polar Cap
Water (H2O) ice
Low elevation
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South Polar Cap
Carbon dioxide (CO2) ice
High elevation
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Changing shape of the South Polar Cap due to
seasons
Frost
Cap
Spring
Winter
Summer
MOLA data indicate that this eroding layer is
about 10 cm thick
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Polar Caps composed of hundreds of layers of ice
and dust
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Snow melt as possible mechanism for pit erosion
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Polygonal ground as indicator of freeze-thaw
process
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So how do we get these longer seasonal changes on
Mars?
The obliquity of Mars may have varied from
almost 0 60 degrees
The precession may have changed climate
dramatically in the past on timescales of 25,000
175,000 years
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Temperature change on Mars due to change in
eccentricity
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Present and past climates of Mars may be very
different
Present cold/dry
Past cold and moist
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Results from Viking Lander Gaschromatograph -
Mass spectrometer
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• Viking Biology Experiments
• Labeled release experiment, looked for signs of
  metabolism
• Pyrolytic release experiment, looked for signs of
  photosynthesis
• Gas exchange experiment, looked for signs of
  respiration

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In 1996, possible fossils were found in a
meteorite from Mars!
ALH 84001 originated as a slowly-cooled igneous
rock in the Martian crust, was excavated by an
impact, altered by fluids, and finally sent to
Earth by another impact. The consensus among most
researchers is that these are not fossils
butludae naturae (playthings of nature), of
inorganic origin.
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More pseudofossils from Martian meteorite ALH
84001
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Carbonates in Martian meteorite ALH 84001 formed
by shock
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Carbonate globules in Martian meteorite ALH 84001
are of inorganic origin
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