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

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

7. Wind-scoured rocks are called “Yardangs”

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

10. Wind erosion features on Mars

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

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

13. Changing shape of the South Polar Cap due to seasons
Frost
Cap
Winter
Spring
Summer
MOLA data indicate that this eroding layer is about 10 cm thick

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

15. Snow melt as possible mechanism for pit erosion

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

17. 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

18. Temperature change on Mars due to change in eccentricity

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

20. Results from Viking Lander Gaschromatograph - Mass spectrometer

21. 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

22. In 1996, possible “fossils” were found in a meteorite from Mars!
ALH 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.

23. More “pseudofossils” from Martian meteorite ALH 84001

24. Carbonates in Martian meteorite ALH 84001 formed by shock

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