ASTRON 1F03 Lecture Notes - Lecture 9: Protoplanetary Disk, Martian Meteorite, Viking Program
18 Dec 2015
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If sheltered from direct sunlight, water ice can persist. Plenty of ice in high latitude (near poles). Viking probes tested the biological responses (inconclusive: perchlorate). Suv sized full wet chemistry lab on board. Atmospheres of the inner planets: mercury, venus, earth, mars, young planets, forming primary atmospheres, captured gases in a protoplanetary, sunlight heated the atmospheres. Rapid thermal motion of light atoms and: volcanoes released gases and comets and asteroids contributed water and other disk, mostly hydrogen and helium. molecules caused the primary atmospheres to escape. molecules to form secondary atmospheres. Mars 5. 0 km/s: atmosphere gas particle speed. Hydrogen (weight 2): average speed 2. 7 km/s at 27 c. Enough particles at higher than average speeds (say 5 6x average) to lose a lot over 4 billion years if that speed is greater than escape velocity. New planets from primary atmospheres by sweeping up gas in the accretion disk. All terrestrial bodies lost their primary atmospheres.
