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GEOL3045: Planetary Geology Lysa Chizmadia Mercury From Mariner 10 to Messenger Lysa Chizmadia Mercury From Mariner 10 to Messenger
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Introduction Closest planet to Sun 5.8 x 10 7 km (0.38 AU) Diameter = 4880 km Smaller than Ganymede & Titan Mass = 3.3 x 10 23 kg Surface T: 90-700 K 3:2 resonance with the Sun 3 rotations for every 2 orbits 88 days and 59 days Closest planet to Sun 5.8 x 10 7 km (0.38 AU) Diameter = 4880 km Smaller than Ganymede & Titan Mass = 3.3 x 10 23 kg Surface T: 90-700 K 3:2 resonance with the Sun 3 rotations for every 2 orbits 88 days and 59 days Image from: http://www.nineplanets.org/mercury.html Orbit highly eccentric Aphelion = 70 million km Perihelion = 46 million km Irregularities in orbit Thought to be Vulcan Supports general theory of relativity
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Mercury vs. Moon Similarities Heavily cratered Old surfaces w/ smooth terrains Caloris basin simliar to Lunar Maria Craters near poles in permanent shadow Radar data suggest ice in N pole craters Similarities Heavily cratered Old surfaces w/ smooth terrains Caloris basin simliar to Lunar Maria Craters near poles in permanent shadow Radar data suggest ice in N pole craters Differences Mercury has much higher density 5.43 vs. 3.34 g/cm 3 2nd densest body in solar system Indicates very large Fe core 1800-1900 km ~75% volume w/ very thin silicate crust 500-600 km Very thin atmosphere From solar wind Image from: http://en.wikipedia.org/wiki/Mercury_%28planet%29
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Mariner 10 Launched in 1974 3 orbits in 2 years Mapped 45% of surface Discovered escarpments 100’s km high From surface shrinkage of ~0.1% (~1 km) Reanalysis suggests recent volcanism More data needed to confirm Launched in 1974 3 orbits in 2 years Mapped 45% of surface Discovered escarpments 100’s km high From surface shrinkage of ~0.1% (~1 km) Reanalysis suggests recent volcanism More data needed to confirm Image from: http://www.nineplanets.org /spacecraft.html#marin10
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Messenger Launched in 3 Aug 2004 Will orbit starting in 2011 ~March 18th First fly by January 2007 Launched in 3 Aug 2004 Will orbit starting in 2011 ~March 18th First fly by January 2007 Images from: http://messenger.jhuapl.edu/gallery/sciencePhotos/view.php?gallery_id=2 Previously unseen side Matisse Crater Surface Spectra
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Messenger Designed to answer following questions: Mercury’s high density Geological history Nature of magnetic field Structure of core Whether there really is ice are poles Determine source of tenuous atmosphere Designed to answer following questions: Mercury’s high density Geological history Nature of magnetic field Structure of core Whether there really is ice are poles Determine source of tenuous atmosphere Image from: http://en.wikipedia.org/wiki/MESSENGER
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Summary Mercury closest to Sun 3:2 resonance with Sun Highly eccentric orbit Confirms general relativity Similar to Moon Heavily cratered & smooth terrains Different from Moon Tenuous atmosphere High density Large FeNi core Mercury closest to Sun 3:2 resonance with Sun Highly eccentric orbit Confirms general relativity Similar to Moon Heavily cratered & smooth terrains Different from Moon Tenuous atmosphere High density Large FeNi core
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Formation of Impact Craters Three stages: Images from: http://cmex.ihmc.us/SiteCat/sitecat2/crater.htm Image from: http://www.chiemgau-impact.com/images/tuetten/image022.jpg
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Formation of Complex Craters Images from: http://cache.eb.com/eb/image?id=96799&rendTypeId=4
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Crater Rays Filamentus, high- albedo material Rays are ejecta from craters Cratering exercise Filamentus, high- albedo material Rays are ejecta from craters Cratering exercise Image from: http://www.lpod.org/?page_id=391
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