Introduction to the early mars III special section and key questions from the third international conference on early mars

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 2125 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 Earths geologic record [Tanaka, 1986].