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

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

Stephen M. Clifford¹, Jack Farmer², Michael H. Carr³, Dave Des Marais⁴, Jean-Pierre Bibring⁵, Robert Craddock⁶, and Horton Newsom⁷

1Lunar and Planetary Institute, Houston, Texas, USA,²Department of Geology, Arizona State University, Tempe, Arizona, USA,³US Geological Survey, Menlo Park, California, USA,⁴NASA Ames Research Center, Moffett Field, California, USA,

5Institut d’Astrophysique Spatiale (IAS), Orsay Campus, France,⁶Center for Earth and Planetary Science, National Air, and Space Museum, Smithsonian Institution, Washington, DC, USA,⁷Institute of Meteoritics, University of New Mexico, Albuquerque, New Mexico, USA

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 itsfirst ~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 fromﬁelds 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 theirﬁrst ~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].

The purpose of the Third Early Mars Conference was twofold:

1. to consider how impacts, volcanism, the presence of abundant water, and the nature of the early terrestrial and Martian climates, affected the physical and chemical environments that existed on both planets>3.0 Ga (especially with regard to the geologic and mineralogical evolution of their surfaces, their hydrologic cycles, the development of life, and the preservation of its signature in the geologic record); and

2. to discuss the investigations that might be conducted by present and future missions to test the hypoth- eses arising from (1).

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.

PUBLICATIONS

Journal of Geophysical Research: Planets

INTRODUCTION TO A SPECIAL

COLLECTION

10.1002/2014JE004643

Special Section:

Early Mars III: Geologic and Hydrologic Evolution, Physical and Climate Environments, and the Implications for Life

Correspondence to:

S. M. Clifford, [email protected]

Citation:

Clifford, S. M., J. Farmer, M. H. Carr, D. Des Marais, J.-P. Bibring, R. Craddock, and H.

Newsom (2014), Introduction to the Early Mars III Special Section and Key Questions from the Third International Conference on Early Mars,J. Geophys.

Res. Planets,119, 1892–1894, doi:10.1002/2014JE004643.

Received 22 APR 2014 Accepted 28 MAY 2014

Accepted article online 4 JUN 2014 Published online 15 AUG 2014

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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 Noachianﬂood volcanism [Rogers and Nazarian, 2013].

References

Ansan, V., and N. Mangold (2013), 3D morphometry of valley networks on Mars from HRSC/MEX DEMs: Implications for climatic evolution through time,J. Geophys. Res. Planets,118, 1873–1894, doi:10.1002/jgre.20117.

Beaty, D. W., et al. (2005), Key Science Questions from the Second Conference on Early Mars: Geologic, Hydrologic, and Climatic Evolution and the Implications for Life,Astrobiology,5(6), 663–689, doi:10.1089/ast.2005.5.663. [Available at http://online.liebertpub.com/doi/pdf/

10.1089/ast.2005.5.663.]

Chasseﬁère, E., B. Langlais, Y. Quesnel, and F. Leblanc (2013), The fate of early Mars’lost water: The role of serpentinization,J. Geophys. Res.

Planets,118, 1123–1134, doi:10.1002/jgre.20089.

de Villiers, G., M. G. Kleinhans, and G. Postma (2013), Experimental delta formation in crater lakes and implications for interpretation of Martian deltas,J. Geophys. Res. Planets,118, 651–670, doi:10.1002/jgre.20069.

Hauber, E., T. Platz, D. Reiss, L. Le Deit, M. G. Kleinhans, W. A. Marra, T. de Haas, and P. Carbonneau (2013), Asynchronous formation of Hesperian and Amazonian-aged deltas on Mars and implications for climate,J. Geophys. Res. Planets,118, 1529–1544, doi:10.1002/

jgre.20107.

Hynek, B. M., T. M. McCollom, E. C. Marcucci, K. Brugman, and K. L. Rogers (2013), Assessment of environmental controls on acid-sulfate alteration at active volcanoes in Nicaragua: Applications to relic hydrothermal systems on Mars,J. Geophys. Res. Planets,118, 2083–2104, doi:10.1002/jgre.20140.

Irwin, R. P., III, K. L. Tanaka, and S. J. Robbins (2013), Distribution of Early, Middle, and Late Noachian cratered surfaces in the Martian high- lands: Implications for resurfacing events and processes,J. Geophys. Res. Planets,118, 278–291, doi:10.1002/jgre.20053.

Kahre, M. A., S. K. Vines, R. M. Haberle, and J. L. Hollingsworth (2013), The early Martian atmosphere: Investigating the role of the dust cycle in the possible maintenance of two stable climate states,J. Geophys. Res. Planets,118, 1388–1396, doi:10.1002/jgre.20099.

Le Deit, L., E. Hauber, F. Fueten, M. Pondrelli, A. P. Rossi, and R. Jaumann (2013), Sequence of inﬁlling events in Gale Crater, Mars: Results from morphology, stratigraphy, and mineralogy,J. Geophys. Res. Planets,118, 2439–2473, doi:10.1002/2012JE004322.

Lillis, R. J., S. Robbins, M. Manga, J. S. Halekas, and H. V. Frey (2013), Time history of the Martian dynamo from crater magneticﬁeld analysis, J. Geophys. Res. Planets,118, 1488–1511, doi:10.1002/jgre.20105.

McCollom, T. M., B. M. Hynek, K. Rogers, B. Moskowitz, and T. S. Berquó (2013), Chemical and mineralogical trends during acid-sulfate alteration of pyroclastic basalt at Cerro Negro volcano and implications for early Mars,J. Geophys. Res. Planets,118, 1719–1751, doi:10.1002/jgre.20114.

Table 1. Key Science Questions From the Third Conference on Early Mars A. How is the early history of the inner solar system related to Mars?

1. How did early bombardments shape the Martian crust and climate?

2. How were the tectonics of early Earth and Mars similar; how were they different?

3. How did changes in solar luminosity affect the Martian atmosphere and climate?

B. What was the nature of the geophysical evolution of early Mars?

1. How did the formation, initial composition, and differentiation of Mars affect the evolution of its crust, mantle, and core?

2. What processes and consequences were associated with the origin, duration, and demise of the Martian magnetic dynamo?

3. How did volcanism evolve and affect the Martian crust and climate?

C. How did the early Martian environment evolve with respect to its physical, geochemical, and mineralogical attributes?

1. Did early water-related climatic events occur episodically; what were their causes and characteristics?

2. What was the nature of early hydrologic cycles, and what were the processes and timing associated with the sources and sinks of water?

3. What is the detailed stratigraphic record and chronology of aqueous mineral deposits?

4. How completely and accurately have accessible geologic deposits on Mars recorded its early environmental history?

5. How can numerical models enhance our understanding of early Martian climate?

6. How can Earth-based investigations in laboratories and in Mars-analog environments enhance our exploration and understanding of early Martian environments and processes?

D. Did prebiotic chemistry and life occur on early Mars?

1. What were the nature, distribution, and duration of any early habitable environments?

2. Did prebiotic evolution occur on Mars; if so, how did it resemble that on Earth?

3. Which potential landing sites and deposits hold the greatest potential for having preserved a record of habitable environments and any fossils?

4. How can potential biosignatures be sought and recognized in the ancient record?

Acknowledgments

The conveners would like to thank the following organizations for their sub- stantial 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 organiza- tion 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.

Journal of Geophysical Research: Planets

10.1002/2014JE004643

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Rai, N., and W. van Westrenen (2013), Core-mantle differentiation in Mars,J. Geophys. Res. Planets,118, 1195–1203, doi:10.1002/

jgre.20093.

Rogers, A. D., and A. H. Nazarian (2013), Evidence for Noachianﬂood volcanism in Noachis Terra, Mars, and the possible role of Hellas impact basin tectonics,J. Geophys. Res. Planets,118, 1094–1113, doi:10.1002/jgre.20083.

Tanaka, K. L. (1986), The stratigraphy of Mars, Proc. Seventeenth Lunar and Planetary Science Conference, Part 1,J. Geophys. Res.,91(B13), E139–E158, doi:10.1029/JB091iB13p0E139.

Tornabene, L. L., G. R. Osinski, A. S. McEwen, J. J. Wray, M. A. Craig, H. M. Sapers, and P. R. Christensen (2013), An impact origin for hydrated silicates on Mars: A synthesis,J. Geophys. Res. Planets,118, 994–1012, doi:10.1002/jgre.20082.

Journal of Geophysical Research: Planets

10.1002/2014JE004643