"What would happen to an Earth plant if it were just left out in the harsh Martian environment?"
-
Archean paleobarometry
PI: Roger Buick
The objective of this project is to obtain the first quantitative measurements of atmospheric pressure on the early Earth, from the Archean Eon >2.5 billion years ago. This will:
1) improve our understanding of Earths early environment;
2) constrain the development of biogeochemical cycles, notably nitrogen;
3) calibrate greenhouse evolution models by providing data on whether greenhouse forcing gases were major or trace atmospheric constituents;
4) permit testing of hypotheses about Archean oxygen levels; and
5) provide tests for astrobiological models of planetary atmospheres.
Two paleobarometry techniques will be used. The first uses a methodology based on a proven and published paleoaltimetry technique (Sahagian, 1994, 2002) involving the determination of vesicle size distributions from the top and bottom of uninflated basaltic lava flows, then applying the ideal gas law to obtain pressure. The second marries raindrop formation theory (Lorenz, 1993, 1995) with empirical studies of raindrop impact-crater volume (Ghadiri, 2004). Since atmospheric density controls the final size and velocity of raindrops, fossil raindrop imprints on sedimentary surfaces can be used to extract atmospheric pressure. The significance of the proposed study applies to NASA Strategic Sub-goal 3C.2 “Understand the processes that determine the history and future of habitability in the solar system, including the origin and evolution of Earths biosphere”, to NASA Astrobiology Roadmap Goal 4 “Understand how past life on Earth interacted with its changing planetary and Solar System environment” and to ROSES Astrobiology: Exobiology and Evolutionary Biology solicitation research emphasis “Early Evolution of Life and the Biosphere”. The pressure and composition of the Archean atmosphere directly reflects
the cycling of gases through early biological metabolic pathways, and in turn provides the environment constraining subsequent biological evolution. Thus, understanding early atmospheric pressure is a key component in studying the history of planetary habitability, both on Earth and elsewhere.
