Driven in part by three new Penn State hires and a different director (PI), PSARC has charted a new direction focused on the recognition and characterization of microbial life, past and present. At the core of Astrobiology and at the forefront of NASA goals is the construction of a fundamental scientific knowledge base that enables the recognition of signatures of life on the early Earth, in extreme environments, and in extraterrestrial settings. To build this foundation, PSARC proposes a comprehensive and interdisciplinary investigation of biosignatures at all scales, from individual cells to the composition of planetary atmospheres. Our pale blue dot provides the only known example of an inhabited planet. Its record of life extends billions of years into the past, and thus presents a rich variety of indicators of life. Through an integration of education and research, PSARC is dedicated to developing the conceptual, analytical, and technical tools to detect life, extant or extinct. Together with new Co-PIs from UCLA (3) and Caltech (1), we propose to develop novel approaches to detecting and characterizing life, investigate biosignatures in mission-relevant microbial ecosystems and ancient rocks, and evaluate the potential for biosignatures in extraterrestrial settings. Our research includes these exciting new directions:
1. Developing new biosignatures – The development and experimental testing of potential indicators of life is essential for providing a critical scientific basis for the exploration of life in the cosmos. In microbial cultures, potential new biosignatures can be found among isotopic ratios, elemental compositions, and chemical changes to the growth media. Additionally, life can be detected and investigated in natural systems by directing cutting-edge instrumentation towards the investigation of microbial cells, microbial fossils, and microbial geochemical products. Over the next five years, we will combine our geomicrobiological expertise and on-going field-based environmental investigations with a new generation of instruments capable of revealing diagnostic biosignatures. Our efforts will focus on creating innovative approaches for the analyses of cells and other organic material, finding ways in which metal abundances and isotope systems reflect life, and developing creative approaches for using environmental DNA to study present and past life.
2. Biosignatures in relevant microbial ecosystems – Over the next five years, PSARC will investigate microbial life in some of Earth’s most mission-relevant ecosystems. These environments are the Dead Sea, the Chesapeake impact structure, the methane seeps of the Eel River Basin, and Greenland glacier ice. The study of environments serving as analogs to the targets of solar system exploration is a top priority of NASA science. PSARC will target environments that, when studied, provide fundamental information that can serve as the basis for future solar system exploration. These environments have geochemistry, energy availability, or fossilization potential similar to that found on Mars, Titan, or under the ice of Europa. Combining our expertise in molecular biology, geochemistry, microbiology, and metagenomics, we propose to decipher the microbiology, fossilization processes, and recoverable biosignatures from these mission-relevant environments.
3. Biosignatures in ancient rocks – The Earth’s Archean and Proterozoic eons offer the best opportunity for investigating a microbial world, such as might be found elsewhere in the cosmos. The ancient record on Earth provides an opportunity to see what geochemical signatures are produced by microbial life and how these signatures are preserved over geologic time. Researchers have recognized a variety of mineralogical and geochemical characteristics in ancient rocks (sedimentary and igneous rocks; paleosols) that may be used as indicators of: (i) specific types of organisms that lived in the oceans, lakes and on land, and (ii) their environmental conditions (e.g., climate; atmospheric and oceanic chemistry). These possible “biosignatures” include: (a) microfossils and stromatolites; (b) molecular structures (biomarkers) and isotopic compositions of C, N, and H in organic matter; (c) multiple S and O isotope ratios of minerals; and (d) abundance relationships and isotopic compositions of redox sensitive metals (e.g., Fe, Mo, Cr, and rare earth elements). As part of our integrated plan, we will study geochemical, isotopic, and sedimentary signatures of life in order to understand the context in which these biosignatures formed. Ultimately, we will use biosignatures in conjunction with evolutionary genomics to reveal the early history of metabolism and understand the interplay between life, oceans, and atmospheres during these early eons.
4. Biosignatures in extraterrestrial settings – Efforts to detect and characterize life will occur in extraterrestrial settings during remote solar system exploration and through observations of extrasolar planets. To this end, a firm understanding of the abundance and speciation of sulfur gases in the atmospheres of young terrestrial planets is needed. SO2 may have played an important role in both atmospheric chemistry and climate on the early Earth and Mars. PSARC will use a combination of redox thermodynamics, petrology, and atmospheric modeling to constrain the abundance of sulfur gases and elucidate how these gases can be expected to evolve with time on young terrestrial planets. We also propose to continue studies of planet formation in the presence of migration, model radial transport of volatiles in young planetary systems, and continue efforts to directly image jovian planets around nearby white dwarfs. The results will have great relevance to detection of habitable worlds, provide a testable target list for future planet finders, and have broad applicability for delivery of biogenic compounds to potentially habitable planets in diverse systems. The models, for example, predict Kepler will observe potentially habitable “super-Earths” in orbits exterior to transiting hot Jupiters. Finally, PSARC will be involved with searches for M star planetary companions and planets around K-giant stars.
The centerpiece of PSARC is undergraduate and graduate education. Our graduate program includes our Dual-title Ph.D. program in Astrobiology. PSARC has produced 36 Ph.D. scientists, many of whom are still active in the Astrobiology scientific community. At the undergraduate level, we have a highly successful Astrobiology Minor, which attracts excellent students from across the campus. These students often continue on with their education in the graduate programs of other NAI teams. We also have an NSF REU summer program in Astrobiology for non-PSU undergraduates. Over the next five years, we propose to contribute to the research experiences of these visiting students by providing them with individual summer research budgets. PSARC is also heavily involved with the WISE and MURE programs at Penn State, which provide research opportunities for undergraduate female and/or minority students.
Our largest effort at public outreach will be our continuing-education summer Astrobiology teacher’s workshop. This yearly event brings elementary and high school teachers from around the mid-Atlantic region to Penn State to work directly with our co-investigators and students. The teachers learn about the science of Astrobiology and obtain lesson materials that can be brought directly into their classrooms. Our future effort will include a new phase of follow-up education to better establish long-term relationships and partnerships between PSARC and interested teachers.
PSARC has recently forged an outreach partnership with the Whitaker Center for Science and the Arts in Harrisburg, PA. Over the next five-year period, PSARC investigators will provide the center with a public lecture series and interactive demonstrations, as part of the center’s new Forces of Nature permanent exhibit opening in January 2009. A highlight of this gallery and the focal point of our lectures will be a new spherical display system from NOAA called “Science On a Sphere”. The “Science on a Sphere”, a 5-foot-diameter sphere on which digital images of solar system bodies can be projected, will serve as the centerpiece for our lectures and demonstrations. We will also engage the public by moving Astrobiology content to the PSU Earth and Mineral Science Museum’s GeoWall, which is a screen that projects images in 3D. These images will include 3D images of Astrobiology-field experiences, allowing the public to experience in 3D real field-based scientific exploration. Throughout the year, there are other important events during which PSARC Co-PIs and students engage the public, including Exploration Day, AstroFest, and EarthFest.