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Considerations on Terrestrial Iron Depositing Analogs to Earliest MarsIron oxide and hydroxide minerals, including hematite, can mineralize and preservemicrofossils and physical biomarkers (Allen at al., 2004). Preserved remnants of phototrophic microorganisms are recognized as biosignatures of past life on Earth (Schopf, 2006). To date, two types of surface iron depositing environments have been studied as analogs to possible habitable environments on earliest Mars: the highly acidified Rio Tinto River (Iberian Belt, Spain) [Gomez Ortis et al., 2007], and the nearneutral iron depositing Chocolate Pots Hot Spring (Yellowstone National Park, US) [Parenteau at al., 2005]. While phototrophs in the Rio Tinto are only represented by eukaryotic algae (Amaral Zettler et all., 2002), Chocolate Pots is mainly populated with cyanobacteria (Pierson et all., 2000; Brown et all., 2007). Which of these environments is the closer analog to a potentially habitable early Mars? Paleobiological data, combined with recent "tree of life" interpretations, suggest that phototrophic eukaryotes evolved not earlier than 2.5 - 2.8 b.y. after Earth s accretion (4.6 b.y.), while cyanobacteria and /or their iron-tolerant predecessors evolved between 1 - 1.5 b.y. after accretion (Brown et al., 2007). Lindsay and Brasier (2002) postulated that microbial life on Mars surface could have lasted no more than 1-1.5 b.y. after Mars accretion (also 4.6 b.y.). Recent multispectral mapping of Mars suggests that near-neutral wet environments prevailed at approximately this time (Bibring, et al., 2006). Thus, near-neutral iron depositing hot springs such as Chocolate Pots Hot Spring seem to be the more likely habitable analogs for earliest Mars.
Document ID
20070017451
Document Type
Conference Paper
Authors
Brown, Igor I. (NASA Johnson Space Center Houston, TX, United States)
Allen, Carlton C. (NASA Johnson Space Center Houston, TX, United States)
Sarkisova, S. A. (NASA Johnson Space Center Houston, TX, United States)
Garrison, D. H. (NASA Johnson Space Center Houston, TX, United States)
McKay, D. S. (NASA Johnson Space Center Houston, TX, United States)
Date Acquired
August 23, 2013
Publication Date
January 1, 2007
Subject Category
Space Sciences (General)
Meeting Information
2nd International Workshop Exploring Mars and Its Earth Analogues(Trento)
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.