2011 Annual Science Report

NASA Goddard Space Flight Center Reporting  |  SEP 2010 – AUG 2011

Executive Summary

The central goal of the Goddard Center for Astrobiology (hereafter, GCA) is to understand how organic compounds are created, destroyed, and altered during the formation and evolution of a planetary system, leading up to the origin of life on a planet such as Earth. Planetary systems form by collapse of dense interstellar cloud cores. Some stages in this evolution can be directly observed when stellar nurseries are imaged, while other stages remain cloaked behind an impenetrable veil of dust and gas. Yet to understand the origin of life on Earth, we must first develop a comprehensive understanding of the formation of our own planetary system. The clues contained in the most primitive bodies from that formative era (comets and primitive meteorites) are central to advancing our understanding of that epoch and of later delivery of volatiles to Earth. To understand the probability of finding life elsewhere we must understand both the similarities and differences between the evolution of our own system and those surrounding other stars.

The central question of our research is: Did delivery of exogenous organics and water enable the emergence and evolution of life? Our proposed research addresses the heart of Goal 3 of the Astrobiology Roadmap: Understand how life emerges from cosmic and planetary precursors.

The GCA investigation is divided into four Themes:

Theme 1: Establish the taxonomy of icy planetesimals and their potential for delivering pre-biotic organics and water to the young Earth and other planets.
Theme 2: Investigate processes affecting the origin and evolution of organics in planetary systems, and the presence of organics on exoplanets.
Theme 3: Analyze the formation, distribution, abundance, and isotopic composition of complex organics in authentic extraterrestrial samples and advanced laboratory simulations of them.
Theme 4: Develop advanced methods for the in-situ analysis of complex organics in small bodies in the Solar System.

This eighth year of our Astrobiology Program saw major emphasis on research collaborations across disciplines. GCA Team members conducted a vigorous and highly productive research program in all four Thematic areas. We conducted many investigations in the laboratory and in the field (mainly astronomical), as summarized below and in the individual reports of Progress.

Team members participated in numerous meetings and workshops, presenting their scientific results there and in many papers in the scientific literature. Of special note is an invited review published in the Annual Review of Astronomy Astrophysics 2011 (M. J. Mumma & S. B. Charnley, The Chemical Composition of Comets – Emerging Taxonomies and Natal Heritage).

The GCA sponsored two major Workshops during this reporting year:

We hosted the first Workshop on Cometary Taxonomy (March 14-16 in Annapolis, MD, with 35 invited participants. Drs. M. Mumma, S. Charnley, S. Milam, B. Bonev, and Ms. C. Eby organized the Workshop. The scope encompassed the entire temporal span of Planetary System formation, including chemistries in the interstellar natal cloud core and protoplanetary disk, dynamical evolution of material in the disk, the compositional signatures of ices and rocky material in comets, and the taxonomic classification of icy bodies within the principal cometary reservoirs. The emerging taxonomies (based on composition of ices and dust) received major attention, in an attempt to identify congruence and divergence amongst them. Insights gained from space missions to recent comets (Hartley 2, Tempel 1, and Borrelly) and from laboratory investigation of authentic samples returned from comet Wild 2 by Stardust capped this Workshop. Additional details appear under Theme 1.

GCA also co-sponsored an International Workshop on Isotopes in Astrochemistry (5-9 December 2011, Lorentz Center, Leiden University), with 50 invited participants. Scientific Organizers were Drs. S. Charnley and S. Milam (GCA Team), Conel Alexander (CIW Team), and Prof. Ewine vanDishoeck (Leiden University). The aim of the workshop was to obtain a clearer picture of the fate of observed interstellar isotopic fractionation patterns as they were incorporated into the protosolar nebula. A major goal was to ascertain which of the molecular isotopic signatures found in primitive Solar System matter (comets, and carbonaceous meteorites) are indicative of pristine interstellar molecules. Additional details appear under Theme 2.

In addition to planting these seeds for the future, our Team members made significant progress in meeting our scientific goals:

Major Research Accomplishments:

Conclusively demonstrated the presence of indigenous nucleobases and other purines in carbonaceous chondrites, resolving a 50-year-old debate. Report: Dworkin et al.

Found a distinctly different distribution of amino acids in 11 thermally altered meteorites compared to (previously studied) aqueously altered meteorites. Report: Dworkin et al.

With Herschel, achieved a definitive measurement of ocean-like water in the ecliptic comet 103P/Hartley 2, showing that such comets could have delivered Earth’s water. Report: G. Blake

Provided clear evidence for polar and apolar ices (with distinct chemical compositions) in the nuclei of three comets – new clues on their formative history. Reports: Bonev/ Villanueva/ /Paganini

Quantified the composition of primary (parent) volatiles in five additional comets, for inclusion in the taxonomy being developed by our team. Reports: Bonev/ DiSanti/ Gibb/ Paganini/ Villanueva

Formulated improved infrared spectral models for the Sun, and for fluorescent vibrational bands of H2O, HDO, CH4, C2H6, HCN, NH3, C2H2, CO, H2CO, and CH3OH. Report: G. Villanueva

Developed an empirical model for fluorescence efficiencies for the ν2 band of methanol in comets, and applied it to 21P/Giacobini-Zinner. Report: DiSanti

Achieved the most sensitive search ever obtained for biomarkers on Mars and primary volatiles in comets. Reports: G. Villanueva/ Y. Radeva
Achieved first light at millimeter wavelengths with the Large Millimeter Telescope (Mexico). This facility will be a powerful instrument for astrobiology (comets, disks, etc.). Report: W. Irvine

Investigated radiolysis of amino acids and sulfuric acid hydrates in astrophysical ice analogs, relevant to Titan, the interstellar medium, and comets. Report: R. Hudson

Explored alternative avenues to mass-independent fractionation of oxygen isotopes in the protoplanetary disk, through nebular lightning instead of self-shielding of CO. Report: J. Nuth

Investigated X-ray characteristics of an erupting young star (V 1647 Ori), and identified possible charge transfer line emission in a massive star-forming region (the Carina nebula). Report: Petre

Investigated the gaseous fraction (abundances, chemistry) in young protoplanetary disks using Herschel. Report: A. Roberge

Achieved first NIR detections of emission from organic molecules (HCN, C2H2) in the inner regions of young circumstellar disks, and established upper limits for CH4. Report: Mandell

Ruled out the detection of CH4 in the exoplanet HD 189733b, reported previously by Swain et al.; conducted a search for organic signatures in the exoplanet GJ 1241b. Report: A. Mandell

Initiated models for planetesimal evolution in the Nice dynamical model, for the first time including collisions in time evolution studies. Report: M. Kuchner

Advanced dynamical models for comet reservoirs, by showing that Oort cloud comets could be captured from sibling stars in the Sun’s birth cluster & HTCs could be KB objects. Report: Levison

Showed that a single Serenitatis impactor dominates the isotopic signatures of Apollo 17 samples, and developed a new tool (molybdenum) for study of late impact addition. Report: Walker et al.

Demonstrated extraction of amino acids from a carbonate stromatolite sample (Svalbard), via derivitization process developed for SAM/MSL mission. Report: Glavin

Deployed a miniaturized ASTID mass spectrometer on field campaigns in Hawaii and Arizona, and successfully measured evolved gas composition. Report: Glavin

Advanced the technique of laser desorption coupled with mass spectroscopy for in situ analysis of complex organics on astrobiology missions to Mars, comets, asteroids. Report: Brinckerhoff et al.

Investigated perchlorate-induced alterations in organic signatures of samples analogous to Mars sediments, and in an Archaean stromatolite, with variable results. Report: Eigenbrode

Community Service (sample events):

GCA members contributed many articles to the “Encyclopedia of Astrobiology”. W. Irvine contributed some 90 entries and served as an Editor. Report: W. Irvine

GCA co-I W. Irvine served as President of IAU Commission 51 (BioAstronomy) and co-planner of the Origins 2011 (Montpelier, France). He is a co-planner of Origins 2014 (Japan). Report: Irvine

GCA organized and hosted the first “Workshop on Taxonomies of Comets”. Report: Bonev
GCA co-organized a “Workshop on Isotopes in Astrochemistry”. Report: Charnley & Milam

Education and Public Outreach (sample activities):

Dr. Michael Mumma delivered the Inaugural lecture of the Gerald A. Soffen Memorial Lecture Series. Dr. Soffen was a pioneer in Astrobiology and the Search for Life on Mars. Report: Cheung

Dr. Michael Mumma delivered the annual “Starry Night” public lecture (“The Search for Life on Mars”) at the Florida Museum of Science (Gainesville). Report: Cheung

GCA scientists supported two major outreach events at NASA GSFC: “Explore@NASA Goddard Day”, and “Celebrate Goddard Day and Science Jamboree”. Report: Cheung

Co-Investigators Mandell and Roberge gave a public lecture “The Quest for Nova Terra” at the Science Jamboree. Report: Cheung

A 10-week nationally advertised and competed program (“Undergraduate Research Associates in Astrobiology”) introduced selected students to mentored research in Astrobiology. Report: Cheung

We initiated conceptual design for an “Astrobiology Walk” to be installed at the Goddard Visitors Center. The Walk will feature 12 stations with placards featuring aspects of the GCA program.

Published papers

GCA members appeared as lead, principal, or co-author on xxx distinct scientific publications during this reporting period. Individual citations appear in the Bibliography.