P1254503547XUIzH

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Pages 193 - 207
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Mariner 10 Mission to Mercury 1973 - 1974
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Mariner 10 mosaics of Mercury (inbound left
outbound right
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Average speed of gas molecules increase with
increasing T
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The average speed of gas molecules decreases with
increasing mass. Note The escape velocity on
Mercury is 4.3 km/sec (or 10,000 miles/hour)
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The average speed of gas molecules decreases with
increasing mass hence, H2 escapes more readily
from a planet than CO2.
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Radius, mean density and interior structure of
the terrestrial planets
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Mercury
Earth
2900 km
640 km
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Caloris Basin 1,300 km in diameter
Rim crest
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Effects of the formation of the Caloris Basin
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Hilly and lineated terrain
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Some craters on Mercury are quite young as they
have fresh-looking rays
Ray
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Linear cliffs called scarps hundreds of km long
were probably caused by contraction and wrinkling
during cooling of the planet
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Since the obliquity of Mercury is zero, its
rotational axis is perpendicular to is orbital
plane and, hence, areas in the polar regions are
permanently in the shade, suggesting that water
ice may be present?!

N. Pole
Arecibo radar antenna in Puerto Rico
Radar sounding of Mercury
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http//messenger.jhuapl.edu/
Launched August 3rd, 2004 Venus fly-bys October
2006 and June 2007 Mercury fly-bys January 2008,
October 2008, September 2009 Orbits Mercury in
March 2011
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5 Stages in the evolution of Mercury

• Formation, melting, and fractionation
  (Fe,Ni-core, silicate mantle) 4.55 Gy ago
• Planet-wide volcanism, cooling, formation of
  lobate scarps
• 4.5 to 4.0 Gy ago, heavy bombardment, and
  formation of large basins like the Caloris Basin
• Basaltic volcanism, filling of low-lying,
  basin-like features
• Minor impacts, regolith formation

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Mercury summary