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Geologic evolution and cratering history of Mercury

Geologic evolution and cratering history of Mercury. By: G. Neukum, J. Oberst, H. Hoffmann, R. Wagner, B.A. Ivanov Presented by: Kristin Hepper. Global mosaic of Mercury. Facts about Mercury. Closest planet to the sun Mercury  36.2 million miles from the sun

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Geologic evolution and cratering history of Mercury

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  1. Geologic evolution and cratering history of Mercury By: G. Neukum, J. Oberst, H. Hoffmann, R. Wagner, B.A. Ivanov Presented by: Kristin Hepper

  2. Global mosaic of Mercury

  3. Facts about Mercury • Closest planet to the sun • Mercury36.2 million miles from the sun • Earth92.96 million miles from the sun • Smallest planet • Radius 1,500 mi • Earth’s radius 3,959 mi

  4. The Sun and planets drawn to scale The relative radii of the Sun and Planets

  5. Daytime 750 K (890.33 F° ) Nighttime 90 K (-297.67 F°) Temperature • Largest range of temperature of any planet

  6. Geologic Features • Appears lunar-like • Covered with impact-craters • Vast smooth plains • Low density of impact craters

  7. Densely cratered (highlands) Lightly cratered (low-lands) Mercury’s Terrain:2 major types

  8. Highlands • High abundance of large craters • Overlapping • Up to tens of kilometers across • Inter-crater plains • Gently, smoothly-flowing units • Characterized by few craters < 15km in diameter

  9. Crater 100km across

  10. Oldest geologic units on Mercury… • Densely cratered terrain • Inter-crater plains • Age based on impact craters and their corresponding materials

  11. Multi-ring structure Caloris

  12. Low-land plains • Where are they found? • In and around large multi-ring structures • North polar region • Patches in highlands

  13. Origin of low-lands • Volcanic  favored or • Caused by ejecta emplacement

  14. Similar to lunar counterparts Morphology more complex the greater the diameter gets Craters • Crater = a saucer-shaped pit or depression caused by impact

  15. Craters cont… • Simple  Complex crater dimaeter • 10.3 kilometers • Age of craters This crater is 10 km wide

  16. Tectonism on Mercury • NOT tectonically active TODAY • But was active in the past • How do we know? • Lineaments • Lobate scarps • Volatile deposits

  17. Lineaments • Linear topographic features of regional extent • Believed to reflect crustal structure • Ex fault lines, aligned volcanoes, straight stream courses

  18. Lobate Scarps • Represent thrusting events • Caused by rapid cooling and contraction of planet • 550km • Heights vary from 0.1-2km

  19. Seen as bright spots in polar areas Reflected radar signal is similar to water-ice deposits on earth No seasons occur on Mercury So temperatures at poles are stable < 135 K Volatile Deposits Volatile- adj. Evaporating readily at normal temperatures and pressures

  20. Composition of Mercury • IRON • Unlike other terrestrial planets • Concentrated at core • Multispectral images from Mariner 10 • Smooth plains • Dark-blue albedo areas

  21. Geophysical • Due to tidal forces, spin rate slowed • Faulting in the lithosphere • Also see compressional features

  22. Mercury’s endogenic processes have long since ceased Similar to both the earth and the moon Bombardment history Lunar-like Since ~ 3.0Gya cratering has dropped off Mercury now experiences a constant level of bombardment Conclusions

  23. Conclusions cont… • Experienced tectonic activity in the past • Little is known about the surface composition

  24. Future Missions to Mercury • 2009 by ESA • Bepi-Columbo • Includes a lander

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