Ames Research Center maintains a coordinated program that integrates a broad, interdisciplinary investigation of the origins, evolution, and future of habitable environments and life, with a parallel, high-impact, education and public outreach effort. Tracing a path from interstellar materials to inhabited worlds and beyond, the team's research unites investigations of the formation, evolution, and climates of habitable planets; the roles of interstellar chemistry in supplying potential biological precursors to these worlds; the origins and nature of metabolism in the first cells; the impact of established biospheres on planetary chemistry and climate, emphasizing the formation of detectable biosignatures; the response of vegetation to regional climate change; and the potential for life to transcend planetary boundaries through transfer between habitable worlds. The program for education and public outreach captures these themes and builds around the expertise and enthusiasm of the Ames team to develop an engaging and informative package that will be disseminated to national- and international-scale audiences. This is being achieved through partnerships with the California Academy of Sciences, Yellowstone National Park, New York Hall of Science, and several K-14 educational organizations.  Strong conceptual and functional links to multiple NASA missions provide context, motivation, and funding leverage for the research program, along with resource- and audience-sharing opportunities for the education and public outreach program. (David.J.DesMarais@nasa.gov)

The Ames team conducts a multifaceted investigation of the formation, evolution, and climatology of habitable planets. Because extrasolar planets that host surface biospheres are the most likely to be detected by remote spectroscopic search, the team focuses on terrestrial (rocky) planets where liquid water is stable at the surface, and it examines a critical subset of the processes that affect planetary habitability. The research seeks to understand the following:  how protoplanetary disks evolve and form terrestrial planets; what kinds of planetary systems are likely to harbor terrestrial planets; how volatiles are delivered to terrestrial planets by impacting planetesimals, and how impacts affect the climatology of terrestrial planets; the particular evolutionary paths of terrestrial planets that result in habitability; and how external characteristics, such as orbital eccentricity, and internal factors, such as atmospheric circulation, affect the habitability of terrestrial planets. (Sanford.S.Davis@nasa.gov)

Ames researchers link these studies of habitability to two major initiatives in prebiotic organic cosmochemistry.  They are tracing, spectroscopically and chemically, the cosmic evolution of organic molecules from the interstellar medium to protoplanetary disks, planetesimals, and finally onto habitable bodies. They are also examining the abiotic mechanisms of primitive membrane formation under the primordial conditions of a habitable planet. Both initiatives couple spectral and chemical studies of laboratory simulations with astronomical observations and analyses of meteorites and comet dust returned by NASA's Stardust mission. (Louis.J.Allamandola@nasa.gov)

The Ames team addresses the origin of metabolism in the earliest ancestors of cells by testing the hypothesis that proteins might have arisen and initially evolved in the absence of a genome.  In prior research, team members selected for the first time a functional protein from a library of random amino acid sequences using a novel in vitro evolution technique.  They now plan to evolve several proteins capable of performing functions that might have been important for early metabolism, such as synthesis of biopolymers and transport of ions across membranous cell walls.  They will also estimate the frequency of finding a functional prebiotic protein among random protein sequences that might have formed spontaneously.  On the basis of these experiments, they will examine the evolutionary potential of an ensemble of proteins through theoretical and computational modeling. (Andrzej.Pohorille-1@nasa.gov)

Another key effort of the Ames team focuses on how to detect life once it has taken hold on a planet, by characterizing the major factors that govern the formation of potentially diagnostic "biosignatures" in microbial ecosystems. Two ecosystem types are being examined for their particular relevance to astrobiological searches for life (e.g., via Mars or Terrestrial Planet Finder (TPF) missions, respectively):  rock-hosted ecosystems in ophiolite springs, as a potential analog for past or present subsurface life within our solar system, and photosynthetic microbial mats, as the type of biosphere that could be remotely detected on extrasolar planets. Work in the ophiolite springs will examine how microorganisms might leave residual biosignatures by affecting the formation of aqueous alteration minerals, and how biological energy requirements define an "energetically habitable zone" for chemotrophic life. Studies of microbial mats will focus on elucidating the pathways by which photosynthetic productivity is transformed into volatile biosignatures that could be distinguished in the atmospheres of distant planets. (Tori.M.Hoehler@nasa.gov; David.F.Blake@nasa.gov)

The ecosystem-level studies of photosynthetic microbial mats will be extrapolated to a planetary scale by refining and evaluating quantitative models that simulate energy relationships, biogeochemical cycling, trace gas exchange, and biodiversity in these systems. Global-scale fluxes of O₂, CO₂, CH₂ and H₂S and other reduced species are estimated by combining algorithms for the production of trace gas biosignatures with process-level metabolic information from model simulation runs. The ability of the model to explore scenarios and assess implications of experimental findings effectively complements the field-based measurements, and it will begin to assess the consequences of billions of years of ecological change driven by environmental forcing. (Christopher.S.Potter@nasa.gov)

The effects of climate variability on a vegetation-rich biosphere are being examined over intermediate time scales, using South American ecosystems as a model. Previous research by the team demonstrated a strong correlation between vegetation changes at 32 South American sites and variations in sea-surface temperature over a 12-year period, related to the El Niño Oscillation (ENSO). This analysis continues and it utilizes information from satellites (MODIS and ETM+ sensors onboard more recent satellites) to predict backward, or hindcast, vegetation assemblages. Fossil pollen profiles will extend this hindcasting back 15,000 years, and thus assess whether ENSO has caused previously unknown changes in vegetation communities. (Hector.L.Dantoni@nasa.gov)

The Ames team is assessing the potential for life to move beyond its planet of origin, as a potentially important component in the evolution of life in our own solar system. Investigators address natural transport, such as on a meteorite, where survivors must withstand radiation, desiccation, and time in transit. Organisms and ecosystems are being identified that are likely to withstand such rigors, and the mechanisms for their survival are being examined in laboratory experiments and in a space simulator. These organisms and ecosystems will be flown in low Earth orbit (e.g., ESA's EXPOSE facility on the ISS) to test their resistance to the space environment. (Lynn.J.Rothschild@nasa.gov)

The Ames team is in a position to influence strongly the astrobiology content of ongoing and future missions. Studies of planet formation and habitability will benefit the Space Infrared Telescope Facility, the Kepler and Eddington orbiters, and the Terrestrial Planet Finder (TPF) mission. Studies of cosmic ices and organics will be synergistic with the Stratospheric Observer for Infrared Astronomy airborne mission, the Stardust mission, and the proposed Astrobiology Explorer cosmochemistry orbiter mission. Studies of microbial biosignatures will benefit the Mars Exploration Rover mission (2003 and 2004), other future Mars missions, and TPF.

The Ames team serves the needs and interests of the nation's educators, students and public through a high-impact education and public outreach program. Specifically, it works with the California Academy of Sciences (CAS), Yellowstone National Park, and the New York Hall of Science to develop new astrobiology workshops, activities, exhibits, and other products for the public. CAS has chosen to utilize astrobiology concepts to link its natural history museum, planetarium, and aquarium under the theme, "Earth and its Place in the Universe." Ames personnel serve on the CAS design and exhibit development teams. Ames and CAS will also facilitate interactions between researchers and educators in order to develop inquiry-based programs and activities for K-14 students. Yellowstone National Park (YNP) is a highly effective venue for conveying astrobiology-related content. Specifically, the thermal springs that abound in the park support research related to the early evolution of life on Earth, and also to the search for evidence of Martian habitability. The Ames team will work with YNP to introduce astrobiology content into trailside interpretive signs, brochures, and the Yellowstone Resources and Issues Guide. By harnessing the E/PO expertise and resources of these organizations, and by accessing the large and diverse audiences they draw, Ames is engaging a broad cross-section of the public in astrobiology outreach activities. This impact will extend to the professional level by engaging graduate students and postdoctoral associates in the research activities. (Sandra.L.Dueck@nasa.gov)

For more detailed information see the following pages:

Research
Formation and Evolution of Habitable Planets
Prebiotic Organics from Space
Origin and Early Evolution of Proteins and Metabolism
Biosignatures in Chemosynthetic and Photosynthetic Systems
Modeling Ecosystems and Biospheres
Hind-Casting Past Environments
Interplanetary Pioneers
Education and Public Outreach