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Project Reports

• 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 continued work on two Open Time Key Projects for the Herschel Space Observatory, an ESA mission launched in May 2009. Herschel is spearheading the next big advances in our knowledge of planet formation, protoplanetary disk evolution, and debris disks. One project (GASPS) is illuminating the evolution of gas abundances and chemistry in protoplanetary disks over the planet-forming phase. The other (DUNES) has sensitively probed the Sun’s nearest neighbors for signs of cold debris disks associated with extrasolar Kuiper Belts.

  ROADMAP OBJECTIVES: 1.1 1.2

• Astrochemistry Theory and Observation Group NAI Report

  We have continued observational programs designed to explore the chemical composition of comets and establishing their potential for delivering pre-biotic organic materials and water to the young Earth and other planets. State of the art, international facilities are being employed to conduct multiwavelength, simultaneous, studies of comets in order to gain more accurate abundances, distributions, temperatures, and other physical parameters of various cometary species. Additionally, observational programs designed to test current theories of the origins of isotopically fractionated meteorite (and cometary) materials are currently underway. Recent chemical models have suggested that in the cold dense cores of star forming regions, significant isotope enrichment can occur for nitrogen and possibly vary between molecular species and trace an object’s chemical evolution. Observations are being conducted at millimeter and submillimeter wavelengths of HCN and HNC isotopologues for comparison to other nitrogen-bearing species to measure fractionation in cold star forming regions.

  ROADMAP OBJECTIVES: 2.2 3.1 3.2 7.1

• NIR Spectroscopic Observations of Circumstellar Disks Around Young Stars

  As a research scientist in the Planetary Systems Laboratory at NASA GSFC, A. Mandell studies the formation and evolution of planetary systems and the structure and composition of the atmospheres of extra-solar planets utilizing near-infrared spectroscopy. Mandell’s current observing campaigns focus primarily on ground-based and space-based spectroscopy of circumstellar disks and extrasolar planetary transits and secondary eclipses using instruments on the Hubble Space Telescope, the Keck telescope and the Very Large Telescope. Additionally, Mandell assists as a co-investigator on computational studies of terrestrial planet formation and evolution using N-body simulations of planetary accretion.

  ROADMAP OBJECTIVES: 1.1

• Progress Report for 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 continued with one manuscript published and another in preparation. A project on the formation of sulfuric-acid hydrates was completed, and a new project involving thermal chemistry at Europa was started. Studies of frozen acetylene were performed and measurements of the infrared optical constants of frozen hydrocarbon molecules was begun. 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

• 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 in Hawai’i and Chile. 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. For the past several years, Co-I DiSanti’s research has emphasized 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. More recently, we have extended our thinking by suggesting oxidation reactions on grains as a means of interpreting results from our recent observational campaign on long-period comet C/2009 P1 (Garradd), in the fall/winter 2011/2012. We have also made major strides in the development and application of fluorescence models for interpretation of observed line intensities in comets, including an empirical treatment of the n2 band of CH₃OH, led by Co-I DiSanti.

  ROADMAP OBJECTIVES: 3.1 3.2

• Advancing Techniques for in Situ Analysis of Complex Organics

  The overall objective of the line of work associated with technique and protocol development using laser mass spectrometry (MS) is to develop protocols for analysis of complex, nonvolatile organic molecules, such as those that might be found at Mars, Titan, comets, and other planetary bodies, with limited chemical sample manipulation, preparation, processing (as may be required by flight missions). The GCA laser MS effort is complementary to both (i) instrument development work supported by NASA programs such as ASTID, to forward the design and testing of new prototype spaceflight hardware, and (ii) ongoing research and development within Theme 4 of the GCA, concerning analytical chemical sample analysis as well as across GCA (particularly with Theme 3) to define combined analysis techniques that may affect future mission design. There are additionally aspects of this effort that relate to understanding synthetic pathways for certain complex organics in planetary environments.

  ROADMAP OBJECTIVES: None Selected

• Research Activities in the Astrobiology Analytical Laboratory

  We are a laboratory dedicated to the study of organic compounds derived from past and future sample return missions, meteorites, lab simulations of Mars, interstellar, proto-planetary, and cometary ices and grains, and instrument development. This year, we continued our analyses of amino acids in carbonaceous chondrites, identifying large L-enantiomeric excesses in the Tagish Lake meteorite that may point towards abiotic processes that could lead to homochirality. We made the first detection of amino acids in CH and CB chondrites, and used compound-specific isotopic analysis to understand formation mechanisms for amino acids in CM and CR chondrites. We hosted two graduate students, welcomed a new NAI NPP postdoctoral researcher to our laboratory, and participated in numerous public outreach and education events, including providing a lecturer to the annual NAI Santander Summer School. We continued our participation in the OSIRIS-REx asteroid sample return mission and provided support for the Sample Analysis at Mars instrument of NASA’s Mars rover Curiosity.

  ROADMAP OBJECTIVES: 3.1 3.2 7.1

• Progress Report From G. Blake – CIT

  The Blake group has been carrying out joint observational and laboratory program with NAI node scientists on the water and simple organic chemistry in the protoplanetary disk analogs of the solar nebula and in comets. Scientific results continue to flow at a rapid clip. We have followed up our major overview papers outlining the results from our extensive (>100 disks) Spitzer IRS survey of the molecular emission from the terrestrial planet forming region with follow-up work with GSFC scientists on the high spectral resolution ground-based observations of such emission and that from cometary comae (and possible non-transiting exoplanets) using the Keck telescope and the VLT. We have measured the angular scale of the disk emission, and discovered a new transitional disk class characterized by a wide angle molecular wind. We have probed the outer disk’s water emission with the Herschel HIFI instrument, and also measured the (D/H)water ratio in a Jupiter Family Comet for the first time with Herschel – finding a value consistent with that in the Earth’s oceans. Our first Cycle 0 ALMA data are now in hand, and beautifully demonstrate the high angular resolution observations of simple organics in the outer regions of disks and comets that will become possible over the coming years. The full suite of results will permit the first detailed examination of the radial water and gas phase organic chemistry in planet-forming environments.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1 7.2

• Remote Sensing of Organic Volatiles in Planetary and Cometary Atmospheres

  In the last year, we have greatly advanced our capabilities to model spectra of cometary and planetary atmospheres (Villanueva et al. 2012a, 2012b). Using these newly developed analytical methods, we derived the most comprehensive search for biomarkers on Mars (Villanueva et al. 2012, submitted) from our extensive database of high-quality Mars spectra. Furthermore, we retrieved molecular abundances of several comets (Villanueva et al. 2012c, Gibb et al. 2012, Paganini et al. 2012a/b), and of several young circumstellar disks (Mandell et al. 2012). These great advancements have allowed us to understand the infrared spectrum of planetary bodies and their composition with unprecedented precision.

  ROADMAP OBJECTIVES: 1.1 1.2 2.1 2.2 3.1 3.2 7.1 7.2

• Rings in Debris Disks: A Signature of Planets or of Volatiles?

  Marc Kuchner and his collaborator Wladimir Lyra at JPL have developed a new explanation for the origin of eccentric rings in debris disks—like the rings around Fomalhaut and HR 4796. A popular explanation for these rings is that they represent dust shepherded by extrasolar planets, which are often too faint to see. Instead of hidden planets, Kuchner and Lyra’s models invoke a hidden component of gas in these disks, which supports a thermal instability that causes the dust to clump together in narrow eccentric rings. The presence of this instability makes inferring the presence of exoplanets more difficult, but it may aid in planet formation and provide important clues to the history of volatiles in the solar system.

  ROADMAP OBJECTIVES: 1.1 1.2 3.1

• Composition of Parent Volatiles in Comets

  During the period covered by this progress report we observed the Oort cloud comets C/2009 (Garradd) and C/2010 G2 (Hill). We completed our comprehensive study of prebiotic molecules in comet C/2007 N3 (Lulin). We continued our multi-comet surveys of spin temperatures and searches for deuterated species. We conducted spatially-resolved measurements of water rotational temperature, column abundance, and ortho-para ratio in the inner coma of comet 103P/Hartley 2 – the target of NASA the EPOXI fly-by mission. We studied the volatile composition of another Jupiter-family comets – 21P/Giacobini-Zinner. We studied the activity of comet Christensen beyond 3 AU from the Sun.

  ROADMAP OBJECTIVES: 2.2 3.1

• Discovery of a Periodicity in X-Ray Emission From an Erupting Young Star and Diffuse Emission 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 two directions: systematic study of X-ray light curves of a young star that experienced an episodic outburst and spectral characteristics of diffuse X-ray emission from the Carina massive star-forming region. We discovered a periodicity of a day in the highly elevated X-ray emission from a protostar for the first time. This result was press-released from NASA/GSFC, ESA and NAI. We also found a strong X-ray emission line in a diffuse spectrum around Eta Carinae, which may require a non-thermal process such as charge exchange.

  ROADMAP OBJECTIVES: 2.2

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

  We have completed analysis of highly siderophile elements and Os isotopes in seven Apollo 17 impact melt breccias. The resulting large database for impact melt rocks from this site is consistent with a dominant signature imparted to rocks from this site by a single major impactor, most likely the Serenitatis impactor. The composition of this impactor was broadly chondritic, but characteristically enriched in Re, Ru and Pd relative to most chondrites. Studies of diogenites and angrites show that late accretion to small bodies occurred very early in solar system history.

  ROADMAP OBJECTIVES: 1.1

• Fischer-Tropsch Type (FTT) Reactions in the Solar Nebula

  We have pursued this research topic on two fronts over the past year. First we have almost completed construction of the new 10-station FTT experimental system, financed by NASA’s Exobiology R&A Program. This system replicates our original experimental setup in a much more compact fashion and should allow us sufficient flexibility to carry out several very long-term, low-temperature experiments while simultaneously having the capability to do a number of much faster experiments at higher temperatures. The second research front we have pursued is in trying to predict the “global” consequences of potentially extensive FTT reactions on the chemistry of the solar nebula and on protostars in general. In addition to the potential for FTT processes to produce interesting pre-biotic organic molecules such as methyl cyanide, various amino acids and more complex aromatic compounds, or the possibility that the macromolecular organic coating produced via FTT reactions could trap noble gases and carry these materials into planetary bodies, we believe that FTT reactions could have several additional, broader consequences for nebular chemistry – and even possibly for the chemical evolution of the galaxy.

  ROADMAP OBJECTIVES: 1.1

• Advancing Methods for the Analyses of Organics Molecules in Sediments

  Eigenbrode’s astrobiological research focuses on understanding the formation and preservation of organic and isotopic sedimentary records of ancient Earth, Mars, and icy bodies. To this end, and as part of GCA’s Theme IV effort, Eigenbrode seeks to overcome sampling and analytical challenges associated with organic analyses of astrobiology relevant samples with modification and development of contamination tracking, sampling, and analytical methods (primarily GCMS) that improve the recovery of meaningful observations and provide protocol guidance for future astrobiological missions.

  ROADMAP OBJECTIVES: 2.1 4.1 7.1

• Astrobiology/Bioastronomy Through the International Astronomical Union, the Encyclopedia of Astrobiology, and Using the Large Millimeter Telescope for Astrobiological Observations

  Irvine and colleagues at the University of Massachusetts have begun commissioning the Large Millimeter Telescope, the largest single-dish radio telescope in the world operating at short millimeter wavelengths, and are planning observations of organic molecules in comets.

  ROADMAP OBJECTIVES: 3.1

• Summary of Research Accomplishments for L. Paganini

  Dr. Lucas Paganini has performed astronomical observations of six comets that led to four publications in peer-reviewed journals (namely, two papers as first author and two as co-author). In July 2011 he (and colleagues) discovered that comet C/2009 P1 (Garradd) is CO-rich. And in 2012 he (and colleagues) detected carbon monoxide in a comet beyond Jupiter (at 6.26 AU from the Sun), thus setting a new record for detections by infrared (IR) spectroscopy of parent volatiles in comets at relatively large heliocentric distances. Until now considered to be a somewhat impossible task with IR ground-based facilities, these discoveries open up new opportunities for targeting multiple volatile species at low rotational temperatures, as well as the unique possibility to characterize hypervolatiles in distant comets.

  ROADMAP OBJECTIVES: 1.1 3.1 3.2