1. Astronomy190 - Topics in Astronomy Astronomy and Astrobiology Lecture 15 : Ancient Mars Ty Robinson

2. Questions of the Day What is the evidence for liquid water on early Mars? What was different about early Mars that made it possible for liquid water to exist on its surface? What processes have subsequently affected Mars’ ability to sustain liquid water on its surface?

3. Surface Ages

4. Evidence from Space I Mars Earth Mars Riverbeds

5. Evidence from Space II Mars Earth Mars Sedimentary Layers

6. Evidence from Space III Flooding

7. Evidence for Water I Satellite Images –Riverbeds –Sedimentary layers –Flooding Evidence for Water

8. Follow the Water

9. Mars Pathfinder Launch: Dec. 1996 Operation: Jul-Sep 1997 Instruments: - cameras - weather sensors - rock analysis tools

10. Pathfinder Landing landing video

11. Evidence for Water II Satellite Images –Riverbeds –Sedimentary layers –Flooding Pathfinder –Maghemite –Flood plain Evidence for Water

12. Mars Exploration Rovers Launch: Jun, Jul 2003 Operation: Jan 2004 - ? Instruments: - cameras - weather sensors - rock analysis tools - microscope

13. Landing Sites

14. Gusev Crater

15. Extended Mission

16. Landing Sites

17. Minerals from Space

18. Opportunity Landing Site

19. Extended Mission

20. Chlorine and Sediments

21. Evidence for Water III Satellite Images –Riverbeds –Sedimentary layers –Flooding Pathfinder –Maghemite –Flood plain Spirit –Silica deposits Opportunity –Sediments –Blueberries –Chlorine concentration Evidence for Water

22. Questions? Liquid water is not stable on the surface of modern-day Mars because… temperatures are too low surface pressure is too low both surface temperatures and pressures are too low water does not exist on Mars

23. Questions? What must have been different about Mars in the past so that liquid water was stable on its surface? thicker atmosphere thicker atmosphere with more greenhouse gases Mars must have had a stronger magnetic field Mars must have been closer to the Sun

24. Greenhouse

25. Summary

26. Atmospheric Escape Impact Erosion Photolysis Solar Wind

27. Questions of the Day What is the evidence for liquid water on early Mars? What was different about early Mars that made it possible for liquid water to exist on its surface? What processes have subsequently affected Mars’ ability to sustain liquid water on its surface?

28. Quiz 3 - What is one thing you did not understand from today’s lecture? 2 - Explain why increasing chlorine concentrations with depth in a crater is evidence for the existence of water there in the past. 1 - What are three pieces of evidence that point to a wet early Mars which can be seen from space?