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Congratulations to Dr. Michael Mumma who receives the 2010 NASA Exceptional Scientific Achievement Award:
"In recognition of the first definitive detection of methane in the atmosphere of Mars, revealing an active and dynamic planet and a
possible abode for life beyond Earth."


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News 2011

Emerging Classification of Comets Based on Chemical Composition


Dr. Michael Mumma and Dr. Steven Charnley of GCA have published a review article in the Annual Review of Astronomy and Astrophysics 2011 on "The Chemical Composition of Comets - Emerging Taxonomies and Natal Heritage". Cometary nuclei contain the least modified material from the early Solar System, and their compositions reflect a range of processes experienced by material prior to its incorporation in the cometary nucleus. From photometric and spectroscopic surveys of more than 100 comets, taxonomic groupings are emerging that are based on cosmogonic parameters such as composition, isotopic fractionation, and nuclear spin temperatures of primary volatiles, along with dust signatures such as crystallinity and mineralogy. Measurements of nuclear spin ratios (in water, ammonia, and methane) and of isotopic ratios (D/H in water and HCN; N14/N15 in CN and HCN) have provided critical insights on factors affecting formation of the primary species. Analyses of data from space missions to comets (e.g., Deep Impact and Star Dust) provide critically important ground truth for interpreting and expanding the taxonomies derived from the much larger general cometary populations.The authors also combine the dynamical dispersion of icy planetesimals formed in diverse regions of the protoplanetary disk with the emerging taxonomy to address the delivery of water and prebiotic organics by comets to early Earth and other terrestrial planets’ region. 10.19.2011
Ade
DNA Building Blocks Found in Carbon-Rich Meteorites


A team of GCA scientists M. Callahan, J. Stern, D. Glavin. J. Dworkin and their co-investigators found diverse suite of nucleobases and terrestrially rare nucleobase analogs in twelve carbon-rich meteorites. These include denine and guanine, as well as hypoxanthine and xanthine DNA resembles a spiral ladder; adenine and guanine connect with two other nucleobases to form the rungs of the ladder. They are part of the code that tells the cellular machinery which proteins to make. Hypoxanthine and xanthine are not found in DNA, but are used in other biological processes. The discovery adds to a growing body of evidence that asteroids and meteorites are chemical 'factories' that may have been important sources of organic compounds required for the emergence of life on the early Earth. The discovery of new nucleobase analogs in meteorites also expands the prebiotic molecular inventory available for constructing the first genetic molecules. 08.08.11

PNAS Paper

Ade
Variations of Organics in Tagish Lake Meteorite Fragments

Dr. C. Herds at University of Alberta and his Co-Investigators, including Drs. D. Glavin, J. Dworkin, M. Callahan, and J. Elsila of GCA conducted detailed chemical and isotopic analyses of organic materials in four Tagish Lake meteorite specimens. These fragments are among the most pristine meteorite samples as they were collected on the Canadian frozen lake only days after the fall in January 2000. Meteorites and asteroids may have been a source of organic matter (such as amino acids, nucelobases, monocarboxylic acids, sugars, and polycyclic aromatic hydrocarbons) that was necessary for the advent of life on Earth. These molecules probably originally formed in the interstellar medium and/or the solar protoplanetary disk, but was subsequently modified in the meteorites’ asteroidal parent bodies. The researchers found that the Tagish Lake meteorite is heterogeneous: the specimens have undergone different levels of hydrothermal alteration and at least some molecules of prebiotic importance were formed during the alteration on the parent body. 06.09.2011

Science Paper

Met
Jupiter's "Grand Tack" Reshaped the Solar System

Jupiter, the largest planet in the Solar System, is pivotal in shaping the configuration of the entire system, including the small bodies like comets and asteroids. The latest dynamical model shows that Jupiter could form much closer to the Sun at ~3 AU. Its early migratory path could bring it to within 1.5 AU, a region where many of the extrasolar ‘hot Jupiters’ have been observed around other stars. The model was built by Kevin Walsh of the Southwest Research Institute in Boulder, CO and his Co-Investigators, A. Morbidelli and S. Raymond in France, D. O’Brien at LPI in Arizona, and A. Mandell of Goddard Center for Astrobiology. The model demonstrates that Jupiter “tacked” (as in sailing) at 1.5 AU due to the formation of Saturn, then started moving outward towards its present location, leaving a planetesimal disk truncated at 1 AU that would later form the terrestrial planets. Mars had a smaller mass than Earth and Venus due to Jupiter's scattering of planet-forming materials at the location of Mars. The scheme is also consistent with the structure of the present-day asteroid belt. Jupiter’s migration initially empties but then repopulates the asteroid belt, with inner-belt bodies originating between 1 and 3 AU and outer-belt bodies originating between and beyond the giant planets. This explains the significant compositional differences across the asteroid belt with the outer belt populated with volatile-rich (icy) planetesimals and the inner belt with rocky planetesimals. Enough of the icy planetesimals had orbits crossing the terrestrial planets to account for the amount of water delivered to Earth during the period of late heavy bombardment. 06.06.2011

Solar
Variations of Gas Release from Comet Hartley-2

GCA scientists, Drs. Mumma, Bonev, Villanueva, Paganini, DiSanti and an international team of co-investigators measured episodic and spatial variations of eight primary volatiles (H2O, HCN, CH4, C2H6, CH3OH, C2H2, H2CO, and NH3) and two product species (OH and NH2) in comet 103P/Hartley 2 using high-dispersion infrared spectroscopy with large ground-based telescopes in Hawaii and Chile. The primary species were released directly from the comet nucleus, while the product species were produced in the coma. The team quantified the long- and short-term production rates of these volatiles over a three-month interval from October to December 2010 that encompassed the comet’s close approach to Earth, its perihelion passage, and flyby of the comet by the Deep Impact spacecraft during the EPOXI mission. The short-term variations were consistent with nucleus rotation when compared with other observations. These measurements helped to determine the composition of Hartley-2, which is the only comet from the Kuiper Belt to be so categorized. 5.17.2011
HD 189733b
No Methane Emission from the Exoplanet HD189733b

A GCA team consisting of Drs. A. Mandell, L.D. Deming, M.J. Mumma and other colleagues used the Keck II telescope in Hawaii to obtain high-resolution near IR spectra of the exoplanet HD189733b. HD189733b is a transiting "hot Jupiter" from which strong thermal IR radiation has been detected by Deming et al 2006. The team attempted to confirm a prior report of the detection of a bright methane emission from the planet using ground-based medium-resolution spectral data at 3.25 micron. Their analysis of the new high-resolution data with models that incorporated the latest molecular databases exclude an astrophysical source for the emission. They conclude instead that the signal most closely matches the signature of water vapor from the Earth’s atmosphere, and the previous detection is most likely a data reduction artifact. Their paper appears in a recent issue of the Astrophysical Journal. - 2.1.2011
HD 189733b
Left-Handed Amino Acids Found in More Carbon-Rich Meteorites

A team of GCA scientists, Drs. D. Glavin, M. Callahan, J. Dworkin, and J. Elsila analyzed samples from nine carbon-rich meteorites (CI, CM, and CR carbonaceous chondrites). They found that most of these meteorites have an excess of left-handed amino acids. The amount of the excess seems to correlate with the degree of water alteration on the parent asteroid body. Life on Earth uses only left-handed amino acids. The new result extends their 2009 discovery to a wider variety of carbon-rich meteorites. It suggests that perhaps left-handed life got its start in space, where conditions in asteroids favored the creation of left-handed amino acid. These amino acids were brought to the early Earth by asteroids and comets impacts and contributed to the origin of only left-handed based protein life on Earth. - 01.17.2011

Glavin's Article in Meteorites and Planetary Science
Left Hand Amino Acid
The Puzzle of Extragalactic DIBs

Diffuse Interstellar Bands (DIBs) have been observed in medium resolution spectra of the Andromeda and Triangulum galaxies taken by GCA scientist Martin Cordiner and his colleagues at Queen's University in Belfast, U.K. They had found these molecular fingerprints before in three other galaxies of the Local Group: our Milky Way, and the Large and Small Magellanic Clouds. DIBs are found everywhere scientists have looked and they exist in diverse astrophysical environments. Though more than 400 DIBs have been documented to-date, no one was able to provide a definitive identification of their molecular structures after detailed comparisons with theoretic and laboratory interstellar molecular spectral data bases. DIBs are likely produced by compounds consisting of large organic molecules of more than 20 atoms and their carriers that are made of carbon. Solving this puzzle would help to explain the process of forming pre-biotic organic molecules that are the building block of life. - 01.10.2011


Cordiner's Paper in ApJ
M31_montage

News: 2011 2010 2009

Home Page (2012 news)

  Other Things
Podcasts
Dr. M. Mumma Audio Interview from Science Friday - Mysterious Gas on Mars - 01.16.09
Dr. M. Mumma Audio Interview - Gas Plume on Mars Signals Potential Life - 01.16.09
Interview on Left Handed Acid from Space - Dr. Danny Glavin
Podcast of Dr. Drake Deming's - There is No Place Like Home - 03.03.09
Comet Wild 2 Podcast
Media / Articles
Review Article on Emerging Classification of Comets based on Chemical Composition
GSFC Press Release on Hartlet-2 - A New Breed of Comet?
Animation on the Stardust path through Wild 2 Jets
Dr. Mumma's Keck Lecture on Comets - 2004
Published Paper in Science - Methane on Mars - 2003
Baking the Rover is Not An Option - 11/20/08
Volcanoes May Have Provided Sparks and Chemistry for First Life - 10.16.08
Mars - An Active Planet (1 of 2)
Mars - An Active Planet (2 of 2) - 1.15.09
Dr. Danny Glavin's Article in "Quirks & Quarks" - 3.21.09
Conceptual Animation Demonstrating Spectroscopy to Find Methane on
Mars - 1.15.09
Visualization of Methane Plume Found on Mars During Northern Summer Season - 1.15.09
Methane on Mars - How Geochemical Processes and How Biological Organisms Under Mars Surface May Have Produced Methane - 1.15.09
Press on Astrobio 2010 Santiago

More Media / Articles...

Key Publications
Absolute Measurements of Methane on Mars
Methane and Water
on Mars: Maps of Active Regions and Their Seasonal Variability
Measurement of the
Isotopic Signatures of Water on Mars; Implications for Studying Methane
Measurements with the Sample Analysis at Mars Instrument
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