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News
Spotlight on GCA Video
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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GCA Scientists to Develop Miniaturized Instrument for In-situ Organics Detections
Goddard scientists (S. Getty, W. Brinckerhoff, M. Callahan, J. Elsila) recently won funding from the Planetary Instrument Definition and Development Program to develop a miniature two-step tandem laser time-of-flight mass spectrometer (L2MS). The L2MS instrument can measure complex nonvolatile organic molecules using advanced laser desorption/ionization (LDI) techniques on solid samples such as "intact" meteorites and planetary rock and ice. The advanced LDI protocols were developed for the miniature L2MS prototype under the auspices of GCA, and have been applied to analyses of meteorites such as Murchison. The instrument is targeted for implementation on future missions to outer planetary satellites, such as Titan or Europa, which are each high-priority astrobiology targets.
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Both Hot and Cold Chemistry form Amino Acids in Carbonaceous Meteorites
Asteroids and their fragments have impacted the Earth for the last 4.5 billion years. Carbonaceous meteorites are known to contain a wealth of indigenous organic molecules, including amino acids, which suggests that these meteorites could have been an important source of prebiotic organic material during the origins of life on Earth and possibly elsewhere. GCA scientists have found amino acids in 13 Antarctica carbonaceous meteorites (CV and CO carbonaceous chondrites and ureilites) that experienced high temperatures in their history. They had previously discovered amino acids in carbon-rich meteorites (CI, CM, and CR carbonaceous chondrites) that experienced much lower temperatures. Their analyses showed that cosmochemical selection mechanisms seem to exist that favors formation of certain classes of amino acids with cold chemistry and other classes with hot chemistry.
Meteoritics and Planetary Science Paper
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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
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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
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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
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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
Nature Paper: A low mass for Mars from Jupiter's early gas-driven migration
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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
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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
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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
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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
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Amino Acids Found in Meteorites from Asteroid 2008 TC3
GCA scientists Drs. Jason Dworkin, Michael Callahan, and Jamie Elsila analyzed fragments of meteorites from the asteroid 2008 TC3 that were recovered from the Nubian Desert of northern Sudan after its impact on October 7, 2008. To their surprise, they detected 19 different amino acids from the sample. The sample had various minerals that only form under high temperatures, indicating it was forged in a violent collision. The team thinks that it's unlikely amino acids from the colliding parent bodies could have survived the conditions that created the meteorite, which endured temperatures of more than 2,000 degrees Fahrenheit (over 1,100 Celsius) – over a long period. The team is planning experiments to test an alternative way to produce amino acids involving reactions in gases as a very hot asteroid cools down. Having more ways to make amino acids in space would increase the chance for finding life elsewhere in the Universe. - 12.15.2010
Glavin's Paper in Meteoritics and Planetary Science
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Now Accepting Applications for 2011-Undergraduate Research Associates in Astrobiology Program
The 2011 Undergraduate Research Associates in Astrobiology Program (UR-AA) is a 10-week program for undergraduate candidates. Research Associates work with a mentor and participate in weekly seminars, laboratory visits, and a field trip to Greenbank Radio Observatory. The URAA program culminates with a poster presentation and a brief seminar given during the last week of the program in a NAI Forum in Astrobiology Research (FAR) Seminar. The application can be found by clicking the Education and Outreach tab.
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Why the Earth and Mars have more glitzy metals than the Moon
The Moon has much less gold, platinum and palladium (highly siderophile elements) compared to Earth and Mars. These heavy elements were likely delivered to the mantles of Earth, Moon and Mars by asteroid impacts after completion of their respective core formation, via a process termed "late accretion". William Bottke at Southwest Research Institute in Boulder, Colorado and GCA Co-I Richard Walker at the University of Maryland built a dynamical model of late accretion with impactors of different sizes. They concluded that the disparity in these elemental abundances could be explained if Earth and Mars received their highly siderophile elements from impacts of a very limited number of large (Pluto-size) bodies, whereas the Moon was struck by much smaller bodies. They note that such Moon-impacting bodies could have delivered enough water to provide an alternate explanation for the presence of water in the lunar mantle. -12.09.2010
Nature Blog
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Europa's Hidden Ice Chemistry
Mark Loeffler (GSFC) and Reggie Hudson (GCA) report reactions between two ices at temperatures hundreds of degrees below freezing without the need for radiation to drive the chemistry. The findings could revamp our understanding of Europa and other icy moons. - 10.5.2010
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Dust Models Paint Alien's View of Solar System
Collaboration between scientists at two NASA Astrobiology Institutes: Marc Kuchner (GCA) and Chris Stark (Carnegie Institute of Washington), produced supercomputer simulations tracking the interactions of thousands of dust grains that show what the solar system might look like to alien astronomers searching for planets. The models also provide a glimpse of how this view might have changed as our planetary system matured.
- 09.23.2010
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GCA Releases Video Highlight in Spanish
Geronimo Villanueva talks about the possibility of life on Mars, trips to remote telescopes, and the research opportunities at NASA in Spanish - 09.14.2010
Spanish Video | Other GCA Video Highlights
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Extrasolar Origin of Oort Cloud Comets
GCA Co-I Hal Levison (SwRI) and his international team demonstrated through computer simulations that many of the most well known Oort Cloud comets, including Halley, Hale-Bopp and, most recently, McNaught, may have been born in orbit around other stars. - 6.10.2010
SwRI press release | Science Express Article
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GCA Scientist L.D.Deming Awarded the Tinsley Prize for Detection of IR Radiation from Exoplanets
Dr. L. Drake Deming of the Goddard Center for Astrobiology (GCA) has been named by the American Astronomical Society as the recipient of the 2010 Beatrice Tinsley Prize. The Tinsley Prize is awarded bi-annually for unusually creative or innovative research in astrophysics. Deming was cited for "...detecting thermal infrared emission from transiting extrasolar planets using the Spitzer Space Telescope. - Press Release 1.13.2010 |
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Sun Glints From Space Signal Oceans and Lakes
In two new videos from NASA's Deep Impact spacecraft, bright flashes of light known as sun glints act as beacons signaling large bodies of water on Earth. These observations give scientists a way to pick out planets beyond our solar system (extrasolar planets) that are likely to have expanses of liquid, and so stand a better chance of having life. - 01.05.2010 |
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Martian Methane Reveals Planet is Not Dead
"Methane is quickly destroyed in the Martian atmosphere in a variety of ways, so our discovery of substantial plumes of methane in the northern hemisphere of Mars in 2003 indicates some ongoing process is releasing the gas." - Dr. M. Mumma - 01.15.09 |
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NASA Scientists Find Clues to a Secret of Life
Amino acids, a basic molecule of life, exist as one of two mirror images, Biology uses the left-handed form for unknown reasons - Dr. Daniel Glavin and Dr. Jason Dworkin- 03.17.09 |
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First Discovery of Life's Building Block in Comet Wild 2
Drs. Jamie Elsila, Daniel Glavin, and Jason Dworkin at the Goddard Center for Astrobiology found glycine in the aerogel collection grids that captured gas and dust samples of Comet Wild 2 as the Stardust spacecraft flew through its jets in January 2004. - 08.17.09 |
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Dual Dust Disks Around Planetary Systems 51 Oph
"Our new observations using Keck Twin Telescopes suggest 51 Ophiuchi is a protoplanetary system with a cloud of dust from comets and asteroids extremely close to its parent star," said Marc Kuchner, a member of the Goddard Center for Astrobiology. " - 09.24.09 |
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