GEOL3045: Planetary Geology

GEOL3045: Planetary Geology

Lysa ChizmadiaMercury

From Mariner 10 to Messenger

Lysa ChizmadiaMercury

From Mariner 10 to Messenger

IntroductionIntroduction Closest planet to Sun

5.8 x 107 km (0.38 AU)

Diameter = 4880 km Smaller than Ganymede &

Titan

Mass = 3.3 x 1023 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 107 km (0.38 AU)

Diameter = 4880 km Smaller than Ganymede &

Titan

Mass = 3.3 x 1023 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

Orbit highly eccentric Aphelion = 70 million

km Perihelion = 46

million km

Irregularities in orbit Thought to be Vulcan Supports general

theory of relativity

Mercury vs. MoonMercury 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/cm3

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

Differences Mercury has much higher

density 5.43 vs. 3.34 g/cm3

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

Mariner 10Mariner 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

MessengerMessenger 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

MessengerMessenger

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

atmosphereImage from: http://en.wikipedia.org/wiki/MESSENGER

SummarySummary 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

Formation of Impact Craters

Formation of Impact Craters

Three stages: Three stages:

Images from: http://cmex.ihmc.us/SiteCat/sitecat2/crater.htm

Image from: http://www.chiemgau-impact.com/images/tuetten/image022.jpg

Formation of Complex Craters

Formation of Complex Craters

Images from: http://cache.eb.com/eb/image?id=96799&rendTypeId=4

Crater RaysCrater Rays Filamentus, high-

albedo material Rays are ejecta

from craters

Cratering exercise

Filamentus, high-albedo material

Rays are ejecta from craters

Cratering exerciseImage from: http://www.lpod.org/?page_id=391