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Executive Summary

Introduction
Our team joined the NASA Astrobiology Institute in February 2009, following selection of our CAN 5 proposal “Setting the stage for life: From interstellar clouds to early Earth and Mars”. As the result of our selection, we have established the New York Center for Astrobiology (http://www.origins.rpi.edu/) at Rensselaer Polytechnic Institute (RPI), in succession to our NASA Specialized Center in Research and Training (NSCORT) in Origins of Life, which was funded from 1998 to 2007. The New York Center for Astrobiology is a partnership between investigators at RPI, the University at Albany, Syracuse University, the University of Arizona, and the University of North Dakota. Our research is devoted to investigating the origins of life on Earth and the conditions that led to the formation of habitable planets in our own and other solar systems. We also place strong emphasis on Education and Public Outreach (EPO) at all levels, and on training the next generation of astrobiologists. Our Center is building upon educational courses and curricula already in place at RPI and partner campuses, as well as developing new initiatives, to deliver an ambitious EPO program.

Our research is grouped into seven projects that form a logical sequence of emerging molecular complexity, from interstellar precursors through protoplanetary disks to the surfaces of the early Earth and Mars. Several projects are developments of previous work under the NSCORT, others (those concerned with the environment of the early Earth and preparation for Mars sample return) are new initiatives. Our team has been greatly strengthened by the hire of seven postdoctoral researchers during the first 6 months of our NAI membership.

Overview of Research
Interstellar Origins of Preplanetary Matter
Organic matter originating in interstellar space is known to exist in our solar system from studies of meteorites and interplanetary dust. This project seeks to understand how these molecules came to exist and to explore how universal they are: do the processes that formed them lead to a rich supply of organic molecules in emerging solar systems elsewhere? The initial step in the evolution of molecular complexity is the formation of simple molecules such as H₂O and CO from the biologically-relevant chemical elements. After hydrogen, oxygen is the most ubiquitous of these elements, yet its abundance and distribution in interstellar environments are controversial. Major reservoirs of O quantified by previous research include ices, silicate dust and gas-phase CO. In a new initiative, a detailed analysis was carried out in 2009 that links, for the first time, studies of ices and CO in molecular clouds to observations of more tenuous environments, where astronomers measure the “depletion” of atomic O and other elements from gas into dust. A major discrepancy has been identified and quantified between the uptake of atomic O into the known primary reservoirs and the observed rate of depletion with respect to density over a wide range of environments. Results imply that O is being sequestered into another form: the most plausible candidate is carbonaceous matter similar in general composition to the O-bearing organics found in cometary particles returned by the Stardust mission. The results of this research are in press for Astrophysical Journal.

We also continued research with infrared spectra from the Spitzer Space Telescope and ground-based facilities with the goal of characterizing interstellar ices and organics. The data quantify abundances in different environments, provide evidence for chemical evolution of these materials, and elucidate the role of physical conditions in controlling how they evolve. Heating that occurs in proximity to newly formed stars leads to physical changes in the ice structure, accompanied by chemical evolution arising from the increased mobility of molecules in the lattice and/or partial sublimation of the most volatile constituents. As an aid to understanding such changes, we have pioneered usage of ternary plots in this field of research: these plots enable the inter-correlation of three variable (such as the abundances of H₂O, CO and CO₂, the dominant species in the ices) in a simple way that facilitates identification of important trends. This work is ongoing and will reach fruition next year.

Processing of Precometary Ices in the Early Solar System
This project considers the extent to which interstellar precursors were modified during the formation and early evolution of the solar system. The spectra of ice features toward regions of low-mass star formation imply that the ices have been thermally processed, i.e., they have been subject to transient heating, the most likely cause of which is heating by shock waves. The long-term goal of this research is to model the evolution of precometary dust and ices subjected to multifluid MHD shock waves in molecular cloud cores and protoplanetary disks, and to predict the spectra of the ices and their sublimates in order to motivate future searches for prebiotic molecules in these environments with SOFIA, Herschel and other observatories. In the reporting period we have worked to advance the theory of multifluid shocks by realistically including the dynamically important effects of dust grains, making excellent progress toward understanding the underlying dust physics and developing approximations to model the grain size distribution. We have also commenced development of a code to simulate shock waves inside protoplanetary disks. We have greatly leveraged this effort recently by initiating a collaboration on shock modeling with Steve Desch from the NAI team at ASU. A by-product of this investigation is the discovery a new mechanism whereby asteroids in the early solar system were heated by magnetic fields. This is a high-risk project but the potential reward is very large: understanding the thermal histories of asteroids is a major unsolved problem.

Pathways for Exogenous Organic Matter to the Early Earth and Mars
Comets are rich in ices and organic molecules. However, because of their relatively high encounter speeds (typically 50 km/s), comets may be relatively inefficient sources of organic compounds. In contrast asteroids, although less rich in organics, may have been more important because their much lower encounter speeds (typically 15 km/s) allow significant quantities of unaltered material to reach the surfaces of the terrestrial planets. This project seeks to quantify the relative contributions of the thermally-altered asteroidal organics and relatively pristine cometary organics to early Earth and Mars. During the reporting period we have utilized the data archive of the Small Main-Belt Asteroid Spectroscopic Survey (SMASS), classifying the spectra of some 1650 asteroids into organic-bearing and organic-free classes, and identifying assemblages analogous to CI1 and CM2 carbonaceous chondrites. Among the several score of distinct meteorite types, only these two types contain significant amounts of organic compounds, including amino acids. We have mapped the proportion of these bodies across the present asteroid belt, noting their distribution relative to the major resonances (Kirkwood Gaps) that represent the primary escape hatches from the belt. Results indicate that the abundances of CI1 and CM2-type assemblages maximize between the 3:1 and 5:2 resonances at 2.5 and 2.82 AU. A significant proportion of the organic-bearing asteroid material reaching the early Earth and Mars will derive from this heliocentric interval. Ongoing work will estimate the initial total mass in this region – and in the adjacent less organic-rich intervals – in order to calculate the amount of CI1 and CM2-type material delivered to the early Earth and Mars in the time interval before the earliest life on Earth.

Impact History in the Earth-Moon System
The flux of interplanetary debris onto the early Earth represents a potential hazard to the emergence of life. Impact craters are few in number on the Earth today because geologic activity and weathering has gradually erased them, but the Moon lacks these erasure processes and therefore retains an excellent record of ancient impacts. The goal of this project is to reconstruct the bombardment history of the Moon, and by proxy the Earth, to establish when the flux of sterilizing impacts declined sufficiently for the Earth to became habitable. Although several hundred lunar impact glasses have been individually dated by us and other investigators using the ³⁹Ar/⁴⁰Ar method, the fidelity of the results is unknown because their Ar diffusivity has not been quantified. We have begun work to determine the Ar diffusivity in both natural lunar glasses and synthetic analogs over a wide range of chemical compositions. Experimental procedures for making synthetic lunar analogs with suitable geometry have been developed during the reporting period. Ten natural impact spherules from the Apollo 16 landing site were analyzed by electron microprobe to determine element abundances, and by Raman spectroscopy to compare atomic bond-lengths. With this characterization completed, the next task will be neutron irradiation and isotopic analysis by a step-heating method to determine Ar diffusivity within both natural and synthetic glasses. Results will be used to model the range of temperature-time histories and the effect on their apparent ages. Comparison of compositionally dependent Ar diffusivities between the natural and synthetic glasses will also show whether other processes such as cosmic ray exposure on the lunar surface have detectably affected the Ar retentivity of the lunar glasses.

Vistas of Early Mars: In Preparation for Sample Return
Mars is a major target for Astrobiology, arguably the most probable body in our solar system beyond the Earth to host life. The ability to analyze in the laboratory real samples of Martian soil from known locations on the planet gathered by a future sample return mission will be an unprecedented development in Mars exploration. To better prepare for the selection and detailed analysis of such samples, we have begun an investigation of terrestrial analogs of minerals known to exist on the Martian surface. Our current focus is on the hydrous sulfate jarosite. We are investigating whether radiometric ages of jarosite can be interpreted to accurately record climate change events on Mars. This project seeks to understanding the conditions required for jarosite formation and preservation on planetary surfaces, and to assess under what conditions its radiometric clock can be reset (e.g., during changes in environmental conditions such as temperature). By studying jarosites formed by a variety of processes on Earth, we will be prepared to analyze and properly interpret ages measured from jarosite obtained from future Mars sample return missions. A review of previous literature indicates that jarosite tends to outgas at significantly lower temperatures than minerals typically analyzed by the ⁴⁰Ar/³⁹Ar method. However, previous experiments are not diagnostic of argon diffusion kinetics for jarosite, determination of which will be a major goal of our future work. Jarosites have been obtained from the Smithsonian Institute, and electron microprobe characterization has enabled us to select and prepare suitable samples for initial argon diffusion analyses. New collaborations have also been established in preparation for fieldwork to collect additional jarosites.

The Environment of the Early Earth
The goal of this project is to provide a window into the environment of the Earth prior to and during the epoch of life’s origin. This is accomplished by analyses of minerals that have survived since that time. As they grow, minerals incorporate trace concentrations of ions and gaseous molecules from the local environment. We have developed techniques that enable an experimental assessment and characterization of the potential for minerals surviving from the Hadean eon to retain chemical memories of prevailing conditions at the time of their formation. We are conducting experiments to calibrate the uptake of species that will serve as indicators of temperature, moisture, oxidation state and atmospheric composition. To date, our focus has been mainly on zircon (ZrSiO₄). Samples available for initial work are from the Jack Hills region of Australia; we recently acquired additional samples of ancient zircons during a field trip to the Acasta Gneiss Complex in northern Canada.

The uptake of hydrous species in zircon was investigated to evaluate the likelihood of they provide a faithful record of the environment of crystallization on the early Earth. Results confirm that zircons do, indeed, incorporate H species when grown in the presence of water at elevated temperature and pressure. However, the mechanism of H-species uptake can depend upon the availability and identity of trivalent cations such as Al³⁺ and the trivalent rare earths in the system, an interesting and unexpected finding that may complicate the analysis. These preliminary results are nevertheless encouraging. We have also studied the uptake and diffusion of atmospheric gases in rock-forming minerals to evaluate the possibility that minerals at or near the surface of the early Earth surface incorporate gas molecules representative of the terrestrial atmosphere at the time. Initial experiments focused upon quartz (the dominant matrix material of the ancient Jack Hills zircon). Results to date reveal that a significant amount of nitrogen (~1000 ppm) is incorporated into the quartz structure, probably in defect sites. N diffusion is slow, an encouraging result because retention of N in quartz over vast expanses of geologic time becomes plausible. The next step is to evaluate the range of natural conditions under which N is taken up in quartz. Current work also investigates the incorporation of aluminum into quartz, with the goal of exploring the nature of the earliest continental crust by developing tools to determine the crystallization environment of ancient quartz.

Prebiotic Chemical Catalysis on the early Earth and Mars
The RNA World hypothesis is a current paradigm for the origins of terrestrial life. Our research is aimed at testing a key component of the paradigm, i.e., the efficiency with which RNA molecules form and grow under realistic conditions. Catalysis on montmorillonite clays has long been regarded as a feasible mechanism for abiotic production and polymerization of key biomolecules such as RNA on early Earth. Research by Ferris and others has shown that RNA chains some 50 units long can be formed in the laboratory from activated RNA monomers using montmorillonite as a catalyst. Our current research builds upon this important discovery, providing insight into the mechanism of the catalytic process. Of 22 montmorillonites investigated, 12 proved to be catalysts. Our research demonstrates that catalytic activity depends on the magnitude of the negative charge on the montmorillonite lattice and the number of cations associated with it: montmorillonites with a low negative charge are catalytic, those with a high negative charge are not. It appears that the charge in non-catalytic montmorillonites blocks the binding of activated monomers. The catalytically active montmorillonites are all Cretaceous with ages ~100 Ma. These catalysts could also have been present on the early (Hadean) Earth if appropriate volcanic eruptives and aqueous environments were available. To address this question, both the eruptives and the environments are being compared between the Cretaceous and the Hadean eons, the latter by investigation of mineral inclusions within Hadean zircons.

EDUCATION AND PUBLIC OUTREACH

Our education and public outreach effort during the reporting period included a suite of six distinct but related activities. Together, they form an integrated program that reflects the strong commitment of our team to EPO in astrobiology and the STEM disciplines.

Undergraduate Education
Our team provides undergraduate students with a breadth of opportunities for educational development. RPI offers a minor degree in Astrobiology to undergraduates majoring in all science disciplines, and also a degree in Interdisciplinary Science that may be designed to enable students to focus their major area of study in Astrobiology and related fields. Although the number of students taking the Astrobiology minor is currently small (~1 per year), we consider it to be a valuable component of our curriculum because of the quality of the students it attracts. In Spring 2009, an especially promising young astrobiologist graduated from RPI with a major/minor in Interdisciplinary Science/Astrobiology. She was admitted to several prestigious schools for graduate study in astrobiology and is now attending the University of Colorado at Boulder.

The upper-level 4-credit course “Origins of Life: A Cosmic Perspective” has been taught by Doug Whittet at RPI for several years. Enrollment in Spring 2009 (21 students) was up 60% compared with the previous year. A wide range of majors were represented, including Biology, Physics, Computer Science, Interdisciplinary Science, Engineering, Electronic Media, Arts and Communication. All course materials were taken on-line for the first time in 2009, using RPI’s Learning Management System, which provides communication tools used for on-line discussion and student feedback as well as access to lecture slides, homework, review papers, and other relevant documents. Students were required to review each lecture and a related list of discussion topics prior to attending class, to facilitate interactive in-class discussion, in preference to the traditional lecture/audience format. This change proved highly successful with much positive feedback. The formal student evaluation score for the course was 4.5/5.0.

Undergraduate Research
A total of 10 undergraduates worked on Astrobiology-related research under the mentorship of NAI faculty during the reporting period (Spring and Summer 2009). These included 6 RPI students, 3 SUNY Albany students, and one student from Agnes Scott College, who visited RPI in Summer 2009 on the NSF-supported REU program in Physics.

Origins of Life Seminar
The weekly Origins of Life Seminar Series at RPI is a focal point for our Astrobiology community: it is a key component of our undergraduate curriculum, it provides opportunities for our students, postdocs and faculty to learn about current research, it serves as a forum for our team to share ideas and discoveries, and it provides a steady flow of interviewees for the Astrobiology series recorded and broadcast by WAMC Northeast Public Radio (see below). Six research seminar talks were presented in Spring 2009 (four by faculty investigators in our NAI team and two by external visiting speakers). Several sessions were used for in-house discussion groups and undergraduate student talks. A total of 32 RPI undergraduates attended the seminar as part of their formal plan of study.

ExxonMobil Bernard Harris Summer Science Camp
RPI was selected as one of only 30 institutions in the nation to host the Bernard Harris Summer Science Camp (BHSSC) in 2009. The BHSSC is an academic program of The Harris Foundation, which takes an active role in shaping education in students entering grade 6,7, or 8. The program is named for Bernard Harris, MD, an accomplished NASA astronaut, physician and entrepreneur. Dr. Harris, the first African American to walk in space, plays an active role in the Summer Science Camp program and other programs for underserved youths. The theme of the Camp held at RPI in June 2009 was “The Quest for Life” (the first time that it has had an Astrobiology focus). A total of 50 middle school students took part in the two-week session. The main objective was for teams of students to propose missions to search for life on another world: targets selected by the student teams included Mars, Europa, and Titan. The students also learned about NASA’s missions to the Moon from NAI scientist John Delano, and were excited to watch the liftoff of the Atlas-V rocket on NASA-TV carrying the LRO and LCROSS spacecraft to the Moon. Field trips took the students to the Albany Pine Bush, the New York State Museum, the Herkimer Diamond Mine, and the New York Museum of Natural History. Scientists associated with our NAI Center formed a panel to judge the proposals during oral and poster presentations by the student teams. The winning team proposed a mission to search for life in Europa: its members had the opportunity to share their excitement and experiences with a wide audience as the result of interviews recorded and broadcast by WAMC for the Astrobiology series on the Best of Our Knowledge (see below).

Astrobiology Teachers Academy
Our first Astrobiology Teachers Academy was held at RPI on July 13–16, 2009. Nine high school science teachers from four local school districts participated. The teachers worked with six NAI scientists to develop ideas for using astrobiology in the classroom. The work of the Academy focused on teacher preparation of learning modules designed to infuse astrobiology themes and content into existing standards-based curricula. The teachers presented the modules they had developed on the final day, describing their learning objectives, content and associated assessment activity. All participants expressed satisfaction with the Academy process and particularly with conversations and question-and-answer sessions between teachers and NAI scientists. Both teachers and scientists remarked that the interaction contributed to their professional growth. All teachers indicated that the rigor of the professional development that characterized the Academy ranked among the highest levels they had experienced during their careers.

WAMC National Public Radio Astrobiology Series
Our team partners with WAMC Northeast Public Radio to publicize the NAI, relevant NASA space missions, new research results, and educational opportunities in astrobiology to a wide and diverse audience. WAMC broadcasts to portions of seven northeastern states (New York, Connecticut, New Hampshire, Vermont, Massachusetts, Pennsylvania, and New Jersey). WAMC is a member of National Public Radio and affiliated with Public Radio International.

Producer Glenn Busby conducted interviews with astrobiologists for broadcast on “The Best of Our Knowledge”, a nationally syndicated program that has an estimated audience of approximately one million listeners per broadcast. Mr. Busby does a superb job of recording and editing the interviews into meaningful segments that capture the essence of each topic and present it in an accessible way without compromising the science. Interviewees include (but are not limited to) visiting speakers at our Origins of Life Seminar Series. During the current reporting period, interviews were recorded with three members of our NAI team (Doug Whittet, Tim Swindle and Bruce Watson) and with two members of other NAI teams (Chris House and James Kasting), as well as with other visiting scientists. Additionally, interviews were recorded with a group of six middle-school students who took part in the Bernard Harris Summer Science Camp at RPI (see above), together with Camp Director Cynthia Smith and science teacher Seamus Hodgkinson.