Early Habitable Environments and the Evolution of Complexity Principal Investigator - David J. Des Marais

INTRODUCTION AND OVERVIEW


Ames Research Center provides a program of integrative, mission-enabled and mission–enabling research on habitability and a thematically related program of education and public outreach focused around informal education in high-impact venues.

David Des Marais, Principal Investigator, gave a NASA Astrobiology Institute (NAI) Ames Team Overview Seminar where he talked about the history of the Ames Team, goals and details of the current research, NASA mission involvement, and education and public outreach.

The overarching goal of our scientific program is to understand the creation and distribution of early habitable environments in emerging planetary systems. A key emphasis of this work is to elucidate, in a conceptual sense, the interactions between contributory processes that operate over vastly differing spatial and temporal scales. In developing an intellectual framework to do so, our aim is to provide a means of integrating not only the investigations that comprise our study, but also the diverse array of applicable research on habitability within the astrobiology community as a whole. Similarly, this framework offers a means of elucidating and formulating the connections between space mission observational data and astrobiology research objectives. This program of research will, in this way, both enable and be enabled by data from the Mars Science Laboratory, Kepler, COROT, and the Spitzer, Herschel, and James Webb Space telescopes. To address our main scientific goal, we will pursue and integrate five objectives corresponding to the cosmochemical, planet-forming, geochemical, and biological processes that combine to yield habitable environments. Our approach is to view habitability as the convergence of factors that permit the emergence, persistence, and evolution of complexity – a tangible property of systems or outcome of processes in each of the areas that we intend to study and, in particular, a core attribute of life. Accordingly, by studying the contributory processes to habitability with reference to their constructive and destructive effects on complexity, and by exploring how that complexity ultimately translates into functionality in biological systems, we will provide a tangible point of connection through which to integrate the results of our investigations.



Cosmic Distribution of Chemical Complexity

Cosmic Distribution of Chemical Complexity
- Lou Allamandola (Lead Co-Investigator)

The first objective of our work is trace, spectroscopically, the cosmic evolution of organic molecules from the interstellar medium to protoplanetary disks, planetesimals and finally onto habitable bodies. Our unique and extensive spectral database will allow us to interpret spaceflight observations far more effectively than was previously possible. In our laboratory work we will simulate the buildup of chemical complexity occurring in interstellar ices, protoplanetary disks, comets, as well as other icy bodies in our solar system. We will characterize the constructive and destructive effects of radiation on molecular complexity in cosmic environments. Our methodology will be extended to a planetary scale by developing a database and instrument concepts that can be applied to the investigation of complex organics on planetary surfaces and subsurfaces. We will develop flight instrumentation to utilize luminescence to detect and characterize any organic compounds encountered during landed missions to the Moon, Mars and elsewhere in the solar system. We will couple spectral and chemical studies of laboratory simulations with astronomical observations and analyses of meteorites and comet dust returned by the Stardust mission. These new results will constrain our modeling of protoplanetary disks.



Disks and the Origins of Planetary Systems

Disks and the Origins of Planetary Systems
- Sanford Davis (Lead Co-Investigator)

The second objective is to develop simulations that will allow us to predict the diversity of planetary systems emerging from protoplanetary disks, with a focus on the formation of planets that provide chemical raw materials, energy, and environments necessary to sustain prebiotic chemical evolution and complexity. We will conduct a multifaceted investigation of the formation, evolution, and climatology of habitable planets. We will examine the emergence of potentially important prebiotic compounds from interactions between radiant energy and protoplanetary disks. We will investigate how these disks evolve to form terrestrial planets, the competition between the time scales for disk dispersal and planet formation in extrasolar systems, the chemical evolution of protoplanetary disks, and the transport of solid phases (ice, grains) across and along an evolving disk. We will simulate the evolution of terrestrial planets about a variety of stellar types and the extent to which they capture water and other volatiles. We will examine synthetic astrometric and radial velocity data sets regarding possible terrestrial planets. The simulations and synthetic data sets will be used to assess data from the Kepler and COROT missions.


Chemistry and Climate of a Prebiotic Atmosphere

The third objective is to model particular planetary systems that can support viable atmospheres, including a focus on chemical consequences of radiation and impacts in early atmospheres. We will use modifications of existing global climate models that would be appropriate to extrasolar planets. We will investigate both the carbon chemistry of cold dry atmospheres as well as impact shock chemistry.



Mineralogical Traces of Early Habitable Environments

Mineralogical Traces of Early Habitable Environments
- Tori Hoehler (Lead Co-Investigator)

The fourth objective is to develop and evaluate a more quantitative methodology for assessing the habitability of early planetary environments – particularly Mars – via capabilities that will be, or might be, deployed in situ. Specifically, we will employ mineralogical analysis to constrain prior environments with emphasis on the main factors that impact habitability – water activity and chemical composition, energy availability and delivery rate, temperature, and pH – and will factor these environmental parameters into an energy balance model that computes biomass density potential, which can become a quantitative measure of habitability. We will evaluate this methodology by application to a variety of Mars analog field settings, with an emphasis on understanding how environmental variability affects the potential to constrain prior physicochemical conditions and the corresponding capability to quantify habitability. In parallel, we will evaluate the efficacy of various analytical and sampling capabilities in quantifying habitability via the prescribed methodology – again, as a function of environmental variability – as a means of emphasizing priorities for flight hardware on future missions.



Origins of Functional Proteins and Early Evolution of Metabolism

Origins of Functional Proteins and Early Evolution of Metabolism
- Andrew Pohorille (Lead Co-Investigator)

The fifth objective is to identify critical requirements for the emergence of biological complexity in early habitable environments by examining key steps in the origins and early evolution of catalytic functionality and metabolic reaction networks. Using proteins, which are the main catalytic agents in terrestrial organisms, we will investigate whether enzymatic activity can arise from an inventory of polymers with completely random sequences that might have naturally existed in habitable environments. We will attempt the first demonstration of multiple origins of a single enzymatic function, and investigate experimentally how primordial proteins could evolve through the diversification of their structure and function. Building on this work, and on our knowledge of ubiquitous protocellular functions and constraints of prebiotic chemistry we will conduct computer simulations aimed at elucidating fundamental principles that govern coupled evolution of early metabolic reactions and their catalysts.



NASA Missions

NASA Missions

The strong mission relevance of this effort, together with the direct participation by several team members in NASA missions, will enhance the roles of astrobiology in current and future missions. Studies of planet formation and habitability will enhance the ongoing observations by the Spitzer, Kepler, and COROT missions and benefit planning for the Terrestrial Planet Finder missions. Studies of cosmic ices and organics will be synergistic with SOFIA, the Stardust, Spitzer and the James Webb Space Telescope missions, and the proposed Extended Red Emission mission. Studies of mineral indicators of habitable environments will benefit the Mars Exploration Rover and Mars Science Laboratory missions and influence planning for Mars sample return. Several of the investigators on this proposal also serve as a Principal Investigator or a Co-Investigator on NASA missions that will be operational during the span of the proposed work. Several are also involved in instrument development and observing strategies.



Astrobiology Workshops, Lecture Series, and Focus Groups

We will further refine emerging concepts of early habitable environments by integrating our efforts with those of other investigators in the NAI and in the broader astrobiology community. Along with our collaborative research, we will maintain a lecture series devoted to early habitability. We will organize a workshop attended by an interdisciplinary group of researchers that will address early habitable environments, develop advocacy for future research and spaceflight observations, and produce a white paper. We will lead NASA Astrobiology Institute focus groups on Mars and on Origins of Life. Early habitable environments are highly relevant to the objectives of these groups.



Education and Public Outreach

Education and Public Outreach
- Sandy Dueck (Lead Co-Investigator)

We will continue to serve the needs and interests of the nation's educators, students and public through a high-impact education and public outreach program. We will continue our partnerships with the California Academy of Sciences, Yellowstone National Park and Lassen Volcanic National Park to develop new astrobiology activities, exhibits, web content, and other products for the public. As part of the Morrison Planetarium program, Ames and the California Academy of Sciences will develop exhibits and inquiry-based programs for K-14 students that address the theme of the origins and evolution of early habitable environments. Partnering with the Ames team, Lockheed Martin Corporation and Yellowstone Park Foundation, will include microbiology and astrobiology content (focusing on Mars and hydrothermal systems) into its visitor centers and in web sites. TERC Corporation, working with Lockheed Martin Corporation and the Ames team, will introduce its Astrobiology curriculum in Maine high schools. The Ames team will reach underrepresented communities by collaborating with Chocktaw Nation's Jones Academy and Langston University in Oklahoma. The team will engage graduate students and postdoctoral associates in its research efforts by providing undergraduate astrobiology courses at Stanford University and University of California, Santa Cruz, and by participating in workshops that introduce educators to astrobiology.



Contribution to NASA and the Astrobiology Program

The expertise, resources and accomplishments of the Ames team will benefit NASA and its Astrobiology Program. Over the past ten years, the Ames team contributed substantially to several Astrobiology Roadmap goals, as documented in over 180 peer-reviewed articles and over 150 abstracts. The team brings a wealth of flight experience through its extensive involvement and accomplishments in NASA missions. Individual team members have made major contributions to the field in key areas, including initiating and organizing AbSciCon, coordinating the revisions of the NASA Astrobiology Roadmap, and representing astrobiology to the science community worldwide and to the public at-large. Ames team members chair the Mars and the Origins of Life focus groups of the NAI. Through their NASA committee membership, as leaders in professional journals and societies, and as educational activists, team members will expand the reach of astrobiology in the professional community and to the next generation. These efforts will greatly enhance the viability and impact of the NASA Astrobiology Institute.