Life_on_Mars-2 - Life on Mars - II Stephen Eikenberry 14...

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Life on Mars - II Stephen Eikenberry 14 October 2010 AST 2037 1
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Life on Mars?? Mars has long been a “favorite” location for extra-terrestrial life 2
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Modern Search for Life on Mars What could we see from Earth? Radio signals (communication) But only present on Earth itself for <100 years Look for O 2 O 2 aggressively combines with rocks on a short timescale So … do not expect free O 2 in large amounts (unless life replenishes it in atmosphere) Not much seen on Mars Look for methane UV solar radiation breaks it down on short timescale So … do not expect free CH 4 in large amounts (unless life replenishes it in atmosphere) Not much seen on Mars 3
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Two Viking landers arrived at Mars in 1976 Identical landers, both stationary (no rover) Cameras and various sensors Included several exo- biology experiments to look for life 4
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Viking: Atmosphere/Soil Tests Atmosphere analysis showed no evidence for methane or silane (SiH 4 ) Soil tests Take a Martian soil sample and bake it Look for amino acids, or other carbon compounds Did not find ANY (!) So little carbon, scientists struggled to explain why (less than the Murchison meteorite) Theory: UV rays plus CO2 produce oxygen temporarily; this oxygen breaks down organic compounds at the surface of Mars, so none left Irony: first active test for life on Mars by humans would first KILL any life it finds … 5
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Viking: Gas Exchange Take Martian soil, add “chicken soup” (broth of yummy nutrients) Wait a few days and check to see if the composition of the gas changes due to respiration/metabolism
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This note was uploaded on 07/26/2011 for the course AST 2037 taught by Professor Eikenberry during the Fall '08 term at University of Florida.

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Life_on_Mars-2 - Life on Mars - II Stephen Eikenberry 14...

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