nai

Project Reports

• Chemical Models of Nebular Processes

  The goal of this task is to determine the chemical composition of icy bodies and establish their potential for delivering pre-biotic organic materials and water to the young Earth and other planets. This is being performed through detailed chemical modeling, coupled with physical evolution, of the interstellar precursor material and of the protosolar nebula. Related observational and laboratory studies are also being undertaken.

  ROADMAP OBJECTIVES: 1.1

• Origin and Evolution of Organics in Planetary Systems

  Professor Fegley’s group at Washington University in St Louis modeled chemistry of outgassed volatiles during accretion of the Earth. Accretion of the Earth, and especially the Moon-forming impact, heats the Earth to temperatures high enough to melt and vaporize its silicate crust and mantle. The Earth has a silicate atmosphere during this phase of its history. As the Earth cools down, the silicate atmosphere collapses and a steam atmosphere forms. This atmosphere is not pure steam, but contains H₂O, H₂, CO, CO₂, CH₄ in varying proportions depending on temperature and pressure. Further cooling leads to a collapse of the steam atmosphere and a gaseous atmosphere forms. This is an early reducing atmosphere with CH₄, H₂, NH₃, and water vapor.

  ROADMAP OBJECTIVES: 1.1 3.1 3.2

• Origin and Evolution of Organics

  The central goal of the Blake group effort in the NASA GSFC Astrobiology node (Origin and Evolution of Organics in Planetary Systems (Mike Mumma, P.I.) is to determine whether complex organics such as those seen in meteorites are detectable in the circumstellar accretion disks that encircle young stars and in the comae of comets. Our program has both observational and laboratory components. We use state-of-the-art telescopes from microwave to optical frequencies, and we have developed novel high frequency and temporal resolution instruments that seek to utilize the unique properties of the terahertz (THz) modes of complex organics. Future observations of such modes with the Herschel and SOFIA observatories promise to revolution our understanding of prebiotic chemistry in both our own and other solar systems.

  ROADMAP OBJECTIVES: 1.1 2.1 3.1

• Current Status and Future Bioastronomy With the Large Millimeter Telescope

  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. The so-called Redshift Search Receiver has an instantaneous bandwidth of 36 GHz, providing the opportunity to simultaneously observe most of the 3mm spectrum of a galaxy, and hence to measure the molecular emissions in this band. It is ultimately intended for use on the Large Millimeter Telescope; however, until the LMT is completed, the receiver is being tested at the Five College Radio Astronomy Observatory’s 14-meter telescope, operated by the University of Massachusetts. Early results indicate that there are striking differences in the apparent chemical composition of molecular clouds in different galaxies. Theoretical work suggests that the relevant effects include differences in both ultraviolet and X-ray environments, and in the importance of shocks.

  ROADMAP OBJECTIVES: 3.1

• Composition of Parent Volatiles in Comets: Oxidized Carbon

  Co-I DiSanti’s research emphasizes the chemistry of volatile oxidized carbon among comets, in particular the efficiency of converting carbon monoxide (CO) to formaldehyde (H₂CO) and methyl alcohol (CH₃OH) on the surfaces of icy grain mantles prior to their incorporation into the nucleus. This process has been shown experimentally to be temperatures in the range _{10 — 20 K. To date we have measured CO, H2CO, and CH3OH in eight long-period (Oort cloud) comets, plus the Jupiter Family comet Tempel-1. The measured conversion efficiencies among comets in our database range from near 90 percent (in comets C/2006 M4 Swan and, more recently, in 8P/Tuttle), to a relatively low efficiency (} 30 percent) in Tempel-1. These measurements are important for establishing the role of comets in replenishing Earth’s oceans and for delivery of the seed organic molecules from which life emerged.

  ROADMAP OBJECTIVES: None Selected

• Astrobiology Sample Analysis Program (ASAP)

  The NAI funded a one year pilot Mars analogue study
  led by NASA Goddard Space Flight Center called the Astrobiology Sample
  Analysis Program (ASAP) for in situ life detection instrumentation
  development and calibration

  ROADMAP OBJECTIVES: None Selected

• A Self-Perpetuating Catalyst for the Production of Organics in Protostellar Nebulae

  When hydrogen, nitrogen and CO are exposed to amorphous iron
  silicate surfaces at temperatures between 500 – 900K, a carbonaceous
  coating forms via Fischer-Tropsch type reactions. Under normal
  circumstances such a catalytic coating would impede or stop further
  reaction. However, we find that this coating is a better catalyst than
  the amorphous iron silicates that initiate these reactions. The
  formation of a self-perpetuating catalytic coating on grain surfaces
  could explain the rich deposits of macromolecular carbon found in
  primitive meteorites and would imply that protostellar nebulae should be
  rich in organic material. Many more experiments are needed to
  understand this system and its application to protostellar systems.

  ROADMAP OBJECTIVES: 1.1 3.1

• 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. We are developing this technique to understand the mass spectra that would be obtained from a meteorite or an unknown rock sample encountered on a remote planetary mission.

  ROADMAP OBJECTIVES: 2.1 2.2 3.1 3.2 7.1

• Accomplishments of Graduate Student Yana Radeva

  Yana L. Radeva is a fourth year Ph.D. student at the University of Maryland – College Park, under the joint mentorship of GCA co-I Prof. Michael A’Hearn (Astronomy Dept.) and Michael Mumma (GCA P. I.). She is investigating the organic composition of comets, a key basis for understanding the formation and evolution of the Solar System, and for assessing delivery of water and organics to terrestrial planets.

  ROADMAP OBJECTIVES: None Selected

• Summer Undergraduate Internship in Astrobiology

  ROADMAP OBJECTIVES: None Selected

• X-Ray Emission From an Intermediate-Mass Young Star, Protostar Binary System and Star-Forming Regions

  High-energy photons in the young stellar environment are known to be important in stimulating chemical reactions of molecules and producing pre-biotic materials that might later be incorporated into comets. Observational tests are sorely needed to assess the significance of such processing for Astrobiology and to guide development of theoretical models for chemical evolution in proto-planetary environments. We have observed X-ray emission from young low- and intermediate- mass stars mainly using the Chandra and XMM-Newton satellites, to understand the short-term X-ray variation and long-term activity evolution. In this reporting period, we studied X-ray and radio activities of individual stars in a binary protostar system and found no apparent connection between the X-ray and radio variability. We observed X-ray emission from the intermediate-mass young star MWC480, which showed stronger absorption than expected from far UV data.

  ROADMAP OBJECTIVES: 3.1

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

  Lunar impact melt rocks have been examined for absolute and relative abundances of the highly siderophile elements. This suite of iron-loving elements can potentially be used to fingerprint the large impactors that struck the Earth and Moon during late stages of bombardment. Results for a variety of Apollo and meteoritic impact melt rocks suggest that some impactors contained highly siderophile elements similar to chondritic meteorites in our collections. Data for several samples, however, are outside of the known chondritic range, and may suggest an origin via a type of impactor that is no longer sampled by the Earth.

  ROADMAP OBJECTIVES: 1.1

• Research Activities in the Astrobiology Analytical Laboratory

  A little over 4.5 billion years ago, our solar system was a disk of gas and dust, newly collapsed from a molecular cloud, surrounding a young and growing protostar. Today most of the gas and dust is in the spectacularly diverse planets and satellites of our solar system, and in the Sun. How did the present state of the planetary system come to be from such undistinguished beginnings? The telling of that story is an exercise in forensic science. The “crime” occurred a long time ago and the “evidence” has been tampered with, as most planets and satellites display a rich variety of geological evolution over solar system history.

  Fortunately, not all material has been heavily processed. Comets and asteroids represent largely unprocessed material remnant from the early solar system and they a represented on Earth by meteorites and interplanetary dust particles (IDPs). Furthermore, telescopic studies of the birth places of other solar systems allow researchers to simulate those environments in the laboratory so that we may characterize the organic material produced.

  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: 1.1 2.1 2.2 3.1 7.1

• Extrasolar Planets

  D. Deming and summer Intern K. Todorov (Connecticut College) measured the emergent infrared spectrum of the giant transiting exoplanet HAT-P-1, using data from the Spitzer Space Telescope. A future extension of this technique to observations of SuperEarths transiting lower main sequence stars may enable the identification of biomarkers in the emergent spectra of life-bearing terrestrial planets

  ROADMAP OBJECTIVES: 1.2

• Organic and Inorganic Acids From Ion-Irradiated Ices

  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, amino acids found in meteorites were investigated, including some acids not found in terrestrial biology. Carbonic acid, a very unstable molecule on Earth, also was studied since it will be stable under Martian conditions and environments in the outer solar system. These projects are part of the Comic Ice lab’s continuing contributions to understanding the chemistry of biologically-related molecules and chemical reactions in extraterrestrial environments.

  ROADMAP OBJECTIVES: 2.2 3.1 7.1

• Breakdown of Methane Due to Electric Discharge: A Laboratory Investigation With Relevance to Mars

  Dust-storm induced electric discharge is one proposed mechanism for the destruction of methane in the martian atmosphere. Theoretical modeling suggests that this mechanism is an efficient way to remove methane. In order to test these mechanisms laboratory facilities are developed. One facility is built to study on static discharge processes in a dust-free atmosphere, the second facility is a dust circulation chamber in which dusts storms can be initiated and electrification in dust storms can be studied. Changes in the chemical composition of the atmosphere are measured by a quadrupole mass spectrometer. Preliminary results show that CO2 is ionized through discharge. Further experiments are under way.

  ROADMAP OBJECTIVES: 2.1