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Pages 193 - 207. Mariner 10: Mission to Mercury 1973 - 1974. Mariner 10 mosaics of Mercury (inbound = left; outbound = right. *. *. *. *. *. *. Average speed of gas molecules increase with increasing T. The average speed of gas molecules decreases with increasing mass.
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Mariner 10 mosaics of Mercury (inbound = left; outbound = right
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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)
The average speed of gas molecules decreases with increasing mass; hence, H2 escapes more readily from a planet than CO2.
Radius, mean density and interior structure of the terrestrial planets
Mercury Earth 2900 km 640 km
Caloris Basin ~1,300 km in diameter Rim crest
Effects of the formation of the Caloris Basin
Some craters on Mercury are quite young as they have fresh-looking rays Ray
Linear cliffs called scarps hundreds of km long were probably caused by contraction and wrinkling during cooling of the planet
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
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
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