Volcanoes on Earth and Mars: A Comparative Study

1. Volcanoes on Earth and Mars: A Comparative Study Joseph C. Kolecki NASA/GRC/LTP

2. Pre-Conference Activities • Think about how new ideas are generated. Is there merit to saying that we establish or express “new ideas” in terms of what we already know? • How does describing “new ideas” in terms of what we already know apply in mathematics? In science? In your daily life? • Using your answers from #1 and #2 above, write out a possible definition for, “Comparative Planetology.” • If you were studying a newly discovered phenomenon on Mars, what basis would you use for developing your understanding?

3. 5. For the philosophers in the group: Given that “new ideas” are expressed in terms of what we already know, is there really anything new under the sun? How did the most ancient people understand their world? In other words: What did THEY know that they could use as a basis for building new ideas? (Hint: What do many of the constellations have in common?) 6. Use a dictionary or on-line resource to acquaint yourself with the words and terms associated with volcanoes. Write out a list of words and their [brief] definitions. 7. Have all of your material from #1 through #6 ready and at hand for our videoconference!

4. Intro to Terrestrial Volcanoes

5. . . . . . . . . . Inner Core Outer Core Mantle (Inner and Outer) Crust (NOT to scale!!!) . . . . . . . . . . . Earth’s Inner Structure .

6. A Matter of Scale Earth’s crust is to Earth more like the Skin of a Baseball is to a Baseball!

7. . . . . . ~30 km (~ 18 miles) . . . . . ~2,900 km (~1,800 miles) . . ~ 5,200 km (~ 3,000 miles) . . . . . ~ 6,400 km (~ 4,000 miles) . . . . Approximate Depths from the Surface

8. . Surface Temperature ~ 0 C . . . Rocky . . Mohorovicic Discontinuity Temperature ~ 1,000 C . . Plastic Mg, Fe, Al, Si, O Gutenberg Discontinuity Temperature ~ 3,700 C . Liquid Fe, S . . Outer/Inner Core Boundary Temperature ~ 4,300 C . Solid Fe . . Inner Core Temperature ~ 5,000 – 7,000 C T/(time) ~ 500 C/(3B Years) Radioactivity in the core Keeps things warm! . . . . More Info! . .

9. Intro to Plate Tectonics Ocean Ocean Upper Crust (Granite (SIMA)) Continental Shelf Abyssal Floor Continental Massif Trench Plate Movement Plate Movement Subduction Lower Crust (Basalt (SIAL)) Melt Zone Mohorovicic Discontinuiry Upper Mantle (Aesthenosphere)

10. Mantle Convection Active Volcanism Plate Boundary Upwelling Subduction Subduction Reminder: The Mantle is in a PLASTIC state!

11. Alfred Wegner (1881-1930) Period ~ 200,000 years

12. Tell-Tale Features!

14. Pacific Ring of Fire

15. Pacific Ring of Fire… …and Present-Day Intraplate Hotspots Pacific Plate

16. Introduction to Volcanoes

17. Composite Volcano High Viscosity Lava with Pyroclastic Materials

18. Mt. Saint Helens Composite Mt. Shasta Mt Rainier Volcanoes

19. Shield Volcano Hawaiian Island-Type Low Viscosity Lava Two Types: AA and Pahoehoe

20. Hawaiian Haleakala (showing young cinder cones in foreground) Shield Hualalai Volcanoes Mauna Loa Mauna Kea

21. Intro to “Line” Volcanoes Presently Active Volcano with Side Vent Earlier (Now Extinct) Volcano Ocean Active Vent Old Pipe Plate Movement Plate Movement Mantle Plume – “Intraplate” Hotspot

22. Intraplate Hotspots Plume Terrestrial Crust Mantle Mantle Core Plume Plume Mantle Mantle Plumes – Real or Fiction?

23. Older Islands Plate Movement Younger Islands Youngest Island Change in Plate Direction Plate Movement Hotspot Line Islands in the Pacific Ocean

24. Line Island Formation Mohorovicic Discontinuity Fixed Hotspot (Mantle Plume)

25. Intro to Mars

26. MARS’ INTERIOR ~ 35 km (N. Hemisphere, MGS) Mantle may be in plastic state. Core is most likely Iron and Iron Sulfide ~ 1,500 km (MGS) Crust is of variable thickness. ~ 80 km (S. Hemisphere, MGS)

27. Maps and Photos

28. Martian Shields: The Tharsis Area (Mons or Montes: Shield – comparable to Hawaiian Islands)

29. Olympus Mons

30. Martian Shield Volcano – Olympus Mons

31. Largest Known Shield Volcano Anywhere in the Solar System!!!

32. Comparing Olympus Mons, Mars Kilauea & Halemaumau, Hawaii Calderas!

33. Another angle on Comparing Halemaumau Crater, Hawaii (Oblique View) Calderas! Olymous Mons, Mars (Oblique View – JPL)

34. Tectonics Some Theories of Formation Martian Magnetism? Hellas-Tharsis? Asteroid Impact Hemispheric Bulge

35. Let’s Think! • Mars is 1/2 the size of Earth. Therefore it has 1/4 the surface area and 1/8 the volume. • Heat is contained in the volume but lost through the surface. Since Mars has 1/8 the volume, what might you guess about the amount of initial heat it had? • The surface to volume ratio of Mars is twice that of Earth (1/4 divided by 1/8 = 2). What does this suggest about its initial rate of heat loss? • Given that Mars began life with a molten interior, what would you expect the interior to be like today? • Do you think that Mars has mantle convection and hotspots like Earth? Do you think that it could have?

36. Tharsis Olympus Mons Ascraeus Mons Could linear Tharsis features be due to passage over a hotspot? Tharsis Montes Pavonis Mons Arsia Mons

37. If there WAS motion over a hotspot, then there must have been a hotspot to move over AND the crust must actually have moved. What additional evidence would you look for to establish crustal motion?

38. Striations: Earth, Atlantic Sea Floor Period ~ 200,000 years • Planetary Magnetic Fields • Mars (Top) • Earth (Bottom) Striations! Striations: Mars, Southern Highlands

39. OK. We’ve made a good case! But is it the only possibility? Suppose we took a look at the planet as a whole: might other possibilities arise?

40. Another Approach: Could there be a relationship between Hellas and Tharsis? N Hellas Tharsis

41. Tarsus

42. A Day to Remember!

43. OK. Now we’ve learned a little about Tharsis. But is this the only volcanic feature on Mars?

44. Other Volcanic Sites

45. Ceraunius and Uranius Tholi Tyrrhena Patera Tharsis Tholus Uranius Patera Ulysses Patera Appolinaris Patera Other Types of Martian Volcanoes (Patera: Collapsed Shield) (Tholus: Composite)

46. TEST: One of these is not like the others! Can you guess which? 1 2 3 4 5 6

47. Post Conference Activities • Having been introduced to terrestrial and Martian volcanoes, determine what terrestrial volcanoes tell us about the natural history of the Earth. Extend these ideas to speculate about the natural history of Mars. • Volcanoes are not the only prominent feature on Mars; there are also plains, basins, arroyos, craters, terraces, frozen poles, and myriad other features. Make a table showing correspondences between these different varieties of features on Mars with similar features on the Earth and/or our Moon. (Can the Moon be used as a source of information in comparative planetology?)

48. How did you picture Mars prior to making this study? How have your impressions of Mars been changed? (For example, does it appear more dynamic to you now than before?) • What expectations does this study excite for studies of other planets in the solar system? How would you study a planet such as Jupiter, a gas giant with no apparent solid surface? Would Earth be a good model for comparison here? What aspects of the Earth might be most relevant? • Finally, what have you learned about the way science operates? Do you believe that scientists routinely go from hypothesis to conclusion? Or is the path they follow more complex?

49. joseph.c.kolecki@nasa.gov