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Seasonal and Daily Changes on Mars

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?. Global dust storms evolve in < 1 months, and last > 3 months.

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Seasonal and Daily Changes on Mars

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  1. 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?

  2. Global dust storms evolve in < 1 months, and last > 3 months

  3. Dust Storms

  4. Dust storm Polar cap Dust storm Africa Local dust storm on Mars Dust storm from Sahara

  5. Dust devil tracks – evidence for local winds and surface fines

  6. Wind-scoured rocks are called “Yardangs”

  7. The material eroded from rocks forms many dunes. Show constant wind direction for long periods of time.

  8. Wind erosion features on Mars

  9. North Polar Cap Water (H2O) ice Low elevation

  10. South Polar Cap Carbon dioxide (CO2) ice High elevation

  11. 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

  12. Polar Caps composed of hundreds of layers of ice and dust

  13. Snow melt as possible mechanism for pit erosion

  14. Polygonal ground as indicator of “freeze-thaw” process

  15. 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

  16. Temperature change on Mars due to change in eccentricity

  17. Present and past climates of Mars may be very different Present – cold/dry Past – cold and moist

  18. Results from Viking Lander Gaschromatograph - Mass spectrometer

  19. 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

  20. 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 but”ludae naturae” (playthings of nature), of inorganic origin.

  21. More “pseudofossils” from Martian meteorite ALH 84001

  22. Carbonates in Martian meteorite ALH 84001 formed by shock

  23. Carbonate globules in Martian meteorite ALH 84001 are of inorganic origin

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