1. Lesson4d1 Working out the global history of Mars

2. Mars is massive enough and far enough from the Sun that it should have held on to much of its atmosphere. There is evidence that Mars use to have a thicker atmosphere, especially if there was once liquid water on the surface. Also, volcanism releases gasses such as CO 2, H 2 O and methane (CH 4 ). This would add to the atmosphere. Something else must have happened.

3. First, did Mars ever have a thicker atmosphere? Evidence would be if there was ever standing water on Mars. Spirit and Opportunity think so. Both landed on Mars in January 2004. Opportunity is still actively researching Mars.

4. Spirit/Opportunity rovers

5. Hematite signal from orbit Hematite is an iron compound which typically forms in the presence of water

6. The Opportunity landing site on Meridiani Planum

8. Eagle Crater

9. Inside Eagle Crater

11. Blue Berries – Hematite spheres

15. Abrasion tool collects samples

16. Spectral analysis confirms Hematite

17. Analysis of rock shows Sulfur, Chlorine and Bromine: All of which are soluble in water

19. High sulfur suggests basalt rocks (Jarosite) that have been dissolved in water

20. Triple combination The triple combination of sulfur, chlorine and bromine make the evidence clear that water was present in the rocks. These three chemicals are deposited when water evaporates and leaves them behind. Combining this with the Hematite which formed within the sedimentary rock layers is conclusive that water was on the surface at Meridiani Planum.

21. Standing water about 3.7 billion years ago. If there was standing water in the distant past on the surface of Mars, then what happened to the atmosphere?

22. Mars Science Laboratory Landed on Aug 5, 2012 Determine whether life ever arose on Mars Characterize the climate Characterize the geology

23. Landing site for MSL – Gale Crater Landing site

30. Smectite clay on earth from 100 million years ago.

31. Model for the formation of Gale crater.