Introduction to the Early Mars III Special Section and Key Questions from the Third International Conference on Early Mars

Abstract

The influx of new data received from recent spacecraft missions, the study of Martian meteorites, recent progress in early climate modeling, the growing evidence for abundant water on early Mars, and the rapid pace of new discoveries about the origin and diversity of life on Earth have reinvigorated interest in both the conditions that prevailed on Mars during its first ~1.5 billion years of geologic history and their potential implications for the development of life. These issues were initially discussed at the First Early Mars Conference, which was held in Houston, Texas, in April 1997 and then again at the Second Early Mars Conference, which was held in Jackson Hole, Wyoming, in October 2004. The scientific content of these meetings was captured in the meeting abstracts, Key Questions (identified by the meeting participants and reported to the Mars Exploration Program Analysis Group, MEPAG), and two associated Special Sections of JGR-Planets, which were published in December 1998 (with 12 papers) and December 2005 (with 25 papers). On 21–25 May 2012, about 100 scientists gathered at the Hyatt Regency Hotel in Lake Tahoe, Nevada to participate in the Third International Conference on Early Mars: Geologic and Hydrologic Evolution, Physical and Chemical Environments, and the Implications for Life. Like its predecessors, the Third Early Mars Conference brought together scientists from fields as diverse as planetary geology, atmospheres, climate, meteoritics, microbiology, and molecular biochemistry, to discuss the conditions that prevailed on the early Earth and Mars during their first ~1.5 billion years of geologic history. Indeed, the study of early Mars is likely to provide critical insight into understanding the nature of the early Earth—for as much as 40% of the Martian surface is believed to date back to a period from which little survives in the Earth's geologic record [Tanaka, 1986]. To ensure enough time to rigorously assess our current understanding of early Martian environments, promote the exchange of new ideas, and address some of the most critical and controversial issues in Mars research, approximately 50% of the total program (which consisted of a mix of invited and contributed talks, panel discussions, poster presentations, several special sessions, a conference dinner, and a mid-conference field trip to Mono Lake) was reserved for discussion and debate. Some of the specific issues and questions that were addressed at the meeting included those identified as Key Questions at the Second Conference on Early Mars, which was held in 2004 [Beaty et al., 2005]. The Third Conference ended with an extended discussion, led by Mike Carr and David Des Marais, to update these “Key Questions” (Table 1), which will serve as the Conference input into the next revision of the MEPAG Science Goals and Objectives document. As with the previous Early Mars Conferences, this special section of JGR-Planets was organized to highlight some of the scientific issues discussed at the meeting. The topics covered include discussions of core-mantle differentiation [Rai and van Westrenen, 2013], the history of the Martian dynamo [Lillis et al., 2013], the preservation state of Noachian terrains [Irwin et al., 2013], the relationship between the morphometry of valley networks [Ansan and Mangold, 2013], crater lake deltas [Hauber et al., 2013; de Villiers et al., 2013], and atmospheric dust [Kahre et al., 2013] in the evolution of the planet's climate; the role of serpentinization in the depletion of the planet's inventory of water [Chassefière et al., 2013]; the origin of the interior deposits of Gale crater [Le Deit et al., 2013]; acid-sulfate alteration of basalt in early hydrothermal systems [Hynek et al., 2013; McCollom et al., 2013]; the impact formation of hydrated silicates [Tornabene et al., 2013]; and the role of impact basin tectonics on Noachian flood volcanism [Rogers and Nazarian, 2013]. The conveners would like to thank the following organizations for their substantial contributions to the success of the meeting: the Lunar and Planetary Institute (for organizational, logistical and financial support), NASA's Mars Program Office (for student travel support), and especially to the NASA's Mars Data Analysis Program which provided the initial funding that made the organization of this meeting possible. Part of this work was carried out at the Jet Propulsion Laboratory/California Institute of Technology, under a contract from National Aeronautics and Space Administration. This is LPI Contribution #1790. The program and abstracts for the Third Early Mars Conference can be found at: http://www.lpi.usra.edu/meetings/earlymars2012/pdf/program.pdf