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Project Reports

• Current Status and Future Bioastronomy

  Irvine and colleagues at the University of Massachusetts have been using a unique new broadband radio receiver to measure the spectra of external galaxies in the 3mm wavelength region, and hence to study the chemistry of their interstellar gas.

  ROADMAP OBJECTIVES: 1.1 2.2 3.1

• NIR Spectroscopic Observations of Circumstellar Disks Around Young Stars

  Using the NIRSPEC instrument on the Keck telescope in collaboration with Dr. Michael Mumma of NASA GSFC and Dr. Geoffrey Blake of CalTech, we made the first discovery of OH ro-vibrational emission in the L band (3 – 4 μm) in the planet-forming (1-10 AU) region of disks around Herbig Ae stars (Mandell et al. 2008). OH is a sensitive tracer of the UV and IR radiation field and the dissociation and recombination of H2 and H2O, and combined with a strong upper limit for H2O emission these observations provide a sensitive constraint on the formation and destruction rate of water and the vertical height of the dust absorbing layer. Line strengths are characteristic of temperatures of ~600K, and the location is constrained to beyond ~1 AU by the spectral line widths, suggesting we are observing the warm molecular layer beyond the inner dust rim.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 7.2

• Debris Disk, Exoplanets, and the Kuiper Belt

  Kuchner developed new models of the dust in the Kuiper Belt, showing how the solar system would appear to an outside observer, and allowing us to compare the solar system to images of other, more massive debris disks. At optical depths similar to that of today’s zodiacal cloud, the Kuiper belt dust cloud is a ~15 AU wide ring containing an azimuthal gap at the location of Neptune. At high dust production rates, the dust cloud appears to shrink to a narrow ring located outside Neptune’s orbit. This narrow ring resembles images of debris disks like those around Fomalhaut and HR 4796.

  Kuchner also studied a relatively new kind of object: a subclass of RS CVn binary stars with infrared excesses. Using dynamical models of dust sculpted by a binary star, Kuchner helped make the case that these new objects may represent dead planetary systems that have been recently stirred by the evolution of the central binary star.

  ROADMAP OBJECTIVES: None Selected

• Evolution of Protoplanetary Disks

  Drs. Aki Roberge and Carol Grady are pursuing studies related to Theme 2 of the NASA GSFC Astrobiology Node, “From Molecular Cores to Planets: Our Interstellar Heritage.” Over the last year, they have begun work on two Open Time Key Projects for the Herschel Space Observatory, an ESA mission launched in May 2009. Herschel is expected to spearhead the next big advances in our knowledge of planet formation, protoplanetary disk evolution, and debris disks. One project (GASPS) will illuminate the evolution of gas abundances and chemistry in protoplanetary disks over the planet-forming phase. The other (DUNES) will sensitively probe the Sun’s nearest neighbors for signs of cold debris disks associated with extrasolar Kuiper Belts. Both projects have begun to produce exciting results, including discovery of a possible new class of ultra-cold debris disks that challenge theories of debris disk evolution and planet formation.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 3.2

• Chemical Models of Nebular Processes

  Theoretical and observational astrochemical studies have been undertaken. We participated in a combined experimental-theoretical project to elucidate the formation pathways to interstellar benzene. We have completed two observational projects related to interstellar organic chemistry. We have detected large carbon-chain anions in two new interstellar sources. A deep7mm line-survey of the very young protostar Cha-MMS1 has demonstrated that this object is very rich in organic molecules, indicative of inactive gas-grain chemistry.

  ROADMAP OBJECTIVES: None Selected

• Advancing Techniques for in Situ Analysis of Complex Organics

  Our research in laser mass spectrometry is part of the overall program of the Goddard Center for Astrobiology to investigate the origin and evolution of organics in planetary systems. Laser mass spectrometry is a technique that is used to determine the chemical composition of sample materials such as rocks, dust, ice, meteorites in the lab. It also may be miniaturized so it could fit on a robotic spacecraft to an asteroid, a comet, or even Mars. On such a mission it could be used to discover any organic compounds preserved there, which in turn would give us insight into how Earth got its starting inventory of organic compounds that were necessary for life. The technique uses a high-intensity laser to “zap” atoms and molecules directly off the surface of the sample. The mass spectrometer instantly captures these particles and provides data that allow us to determine their molecular weights, and therefore their chemical composition. Our recent work has been to understand the different kinds of spectra one obtains when analyzing complex samples that are analogs of Mars and other planetary bodies, such as phyllosilicate-bearing rocks that have been identified on Mars and may indicate past conditions where life could have developed in the presence of water. We also have been improving the instrument to better detect certain kinds of organic compounds in such complex rocks, such as to selectively ionize certain hydrocarbons and simplify data analysis, and to create chemical maps of the sample surface.

  ROADMAP OBJECTIVES: 2.1 2.2

• The Organic Volatile Composition of Comets: C/2000 WM1 and 2P/Encke and a New Fluorescence Model for C2H6 ν5 Applied to Eight Comets

  Yana L. Radeva is a Research Associate at the Catholic University of America, and is conducting her postdoctoral research at NASA’s Goddard Space Flight Center. She commenced her postdoctoral research on June 1, 2010, and is analyzing high-resolution infrared spectra of the Martian atmosphere, in a search for biomarker gases. Radeva published a paper on the organic composition of comet C/2000 WM1 (LINEAR) in Icarus (2010, Volume 206, Issue 2, p. 764-777); and is preparing a paper on the organic composition of comet 2P/Encke. She completed her work on the application of the new fluorescence model for the ν5 band of C2H6 to eight comets. Radeva defended her PhD dissertation, and received her PhD in Astronomy from the University of Maryland on May 21st 2010. Radeva also participated in the Astrobiology Science Conference – AbSciCon 2010 (April 2010), at which she presented the new C2H6 ν5 model.

  ROADMAP OBJECTIVES: None Selected

• High Energy Observations of Planets and Comets

  We used the Swift high-energy mission to acquire UV spectroscopy of several comets, amongst which comet 81P/Wild-2 (the target of the Stardust mission) and comet Lulin. These data allowed us to derive gas production rates of OH (water) as well as various organic species that cannot easily be observed from Earth.

  ROADMAP OBJECTIVES: 3.2

• Fingerprinting Late Additions to the Earth and Moon via the Study of Highly Siderophile Elements in Lunar Impact Melt Rocks

  Two new lunar Apollo 17 poikilitic breccias have been examined for highly siderophile element (HSE) abundances and Os isotopic compositions. Both samples overlap chemically and isotopically with prior analyses of poikilitic breccias, indicating a consistent “fingerprint” for this Serenitatis lithology. New techniques have been developed to provide in situ analysis of breccia sub samples prior to HSE analysis. Pure lunar crust has very low concentrations of all HSE measured, including for the first time, Pd and Pt.

  ROADMAP OBJECTIVES: 1.1

• Research Activities in the Astrobiology Analytical Laboratory

  We are a laboratory dedicated to the study of organic compounds derived from Stardust and future sample return missions, meteorites, lab simulations of Mars, interstellar, proto-planetary, and cometary ices and grains, and instrument development. Like forensic crime shows, the Astrobiology Analytical Laboratory employs commercial analytical instruments. However, ours are configured and optimized for small organics of astrobiological interest instead of blood, clothing, etc.

  ROADMAP OBJECTIVES: 2.1 3.1 3.2 7.1

• The Cosmic Ice Laboratory

  Scientists at the Cosmic Ice Laboratory with the Goddard Center for Astrobiology study the formation and stability of molecules under conditions found in outer space. During the past year, studies of amino-acid destruction were begun, projects on ethane and carbonic acid were completed, and better quantification of Titan organics became possible through our experiments. All of this work is part of the Comic Ice Laboratory’s continuing contributions toward understanding the chemistry of biologically-related molecules and chemical reactions in extraterrestrial environments.

  ROADMAP OBJECTIVES: 3.1 3.2

• Advancing Methods for the Analyses of Organics Molecules in Microbial Ecosystems

  Eigenbrode’s GCA work over the past year has largely focused on developing thermochemolysis methodologies for extracting components of complex organics molecules from samples that pose unique analytical challenges because of their mineral composition. These include iron-oxide rich samples regarded as analogs to ancient aqueous environments on Mars and ancient Earth, as well as perchlorate-laden samples. Eigenbrode is making progress with the method development and has observed some interesting biosignatures relevant to understanding microbial contributions and sedimentary preservation. In addition, Eigenbrode has begun a new collaboration with MIT and Wisconsin teams with the intention of applying innovative techniques to understanding the distribution of stable carbon isotopes in the Archean rock record.

  ROADMAP OBJECTIVES: 4.1 5.1 5.2

• Composition of Parent Volatiles in Comets: Oxidized Carbon

  GCA Co-Investigator Dr. Michael DiSanti continued his work on measuring parent volatiles in comets using high-resolution near-infrared spectroscopy at world class observatories. The goal of this work is to build a taxonomy of comets based on ice compositions, which show considerable variation among comets measured to date. DiSanti’s research emphasizes the chemistry of volatile oxidized carbon, in particular the efficiency of converting CO to H2CO and CH3OH on the surfaces of icy interstellar grains, through H-atom addition reactions prior to their incorporation into comets. The work requires planning and conducting observations, processing of spectra, and development and application of fluorescence models for interpretation of observed line intensities. Emphasis of his modeling effort was on characterizing CH3OH in comets.

  ROADMAP OBJECTIVES: 3.1

• FTT Catalysis of Organic Materials in the Solar Nebula

  The first results from our experiments to simultaneously trap noble gases while synthesizing the macromolecular organic coating on amorphous iron silicate grains were reported at the 2010 LPSC in March and were carried out in collaboration with Drs. Charles Hohenberg and Alex Meshik at Washington University. Grain coatings were made at temperatures of 873K and 673K, yet significant quantities of Xenon and Krypton were trapped while no detectable levels of either Ar or Ne were observed above blank level. FTT synthesis in the solar nebula probably took place at much lower temperatures and the observed trapping of heavy noble gases at such high temperatures is very encouraging for the low temperature studies that we will begin this spring.

  ROADMAP OBJECTIVES: 3.1 3.2

• X-Ray Emission From Intermediate Mass Young Stars, an Erupting Young Star and Diffuse Nebula in the Carina Star Forming Region

  High-energy photons in the young stellar environment are known to be important in stimulating chemical reactions of molecules and producing pre-biotic materials. In this reporting period, we approached this problem from three directions: X-ray characteristics of young intermediate-mass stars, X-ray emission mechanism of a young star that experienced an episodic outburst, and spectral characteristics of the diffuse X-ray emission from the Carina massive star-forming region. In particular, no X-ray detection of two young intermediate-mass stars with high inclinations (PDS 144N, 144S) is consistent with a relation of X-ray absorption against the stellar inclination angle among our earlier samples. The circumstellar gas envelope around the Herbig Ae/Be stars would be thinner in higher latitudes.

  ROADMAP OBJECTIVES: 2.2 3.1