Astrobiology Program investigators Michael Mumma and Steven Charnley from NAI's NASA Goddard Space Flight Center Team have recently published a review entitled The Chemical Composition of Comets: Emerging Taxonomies and Natal Heritage in the Annual Review of Astronomy and Astrophysics.

Cometary nuclei contain the least modified material from the formative epoch of our planetary system, and their compositions reflect a range of processes experienced by material prior to its incorporation in the cometary nucleus. Dynamical models suggest that icy bodies in the main cometary reservoirs (Kuiper Belt, Oort Cloud) formed in a range of environments in the protoplanetary disk, and (for the Oort Cloud) even in disks surrounding neighboring stars of the Sun's birth cluster. Photometric and spectroscopic surveys of more than 100 comets have enabled taxonomic groupings based on free radical species and on crystallinity of rocky grains. Since 1985, new surveys have provided emerging taxonomies based on the abundance ratios of primary volatiles. More than 20 primary chemical species are now detected in bright comets. Measurements of nuclear spin ratios (in water, ammonia, and methane) and of isotopic ratios (D/H in water and HCN; 14N/15N in CN and HCN) have provided critical insights on factors affecting formation of the primary species. The identification of an abundant product species (HNC) has provided clear evidence of chemical production in the inner coma. Parallel advances have occurred in astrochemistry of hot corinos, circumstellar disks, and dense cloud cores. The review addresses the current state of cometary taxonomy and compares it with current astrochemical insights.

Source: NAI Newsletter

Posted by Keith Cowing at 12:08 PM | Permalink | Comments (0)

A new study from NASA Astrobiology Program-funded scientists points to a rapid collapse of Earth's species 252 million years ago.

Since the first organisms appeared on Earth approximately 3.8 billion years ago, life on the planet has had some close calls. In the last 500 million years, Earth has undergone five mass extinctions, including the event 66 million years ago that wiped out the dinosaurs. And while most scientists agree that a giant asteroid was responsible for that extinction, there's much less consensus on what caused an even more devastating extinction more than 185 million years earlier.

The end-Permian extinction occurred 252.2 million years ago, decimating 90 percent of marine and terrestrial species, from snails and small crustaceans to early forms of lizards and amphibians. "The Great Dying," as it's now known, was the most severe mass extinction in Earth's history, and is probably the closest life has come to being completely extinguished. Possible causes include immense volcanic eruptions, rapid depletion of oxygen in the oceans, and -- an unlikely option -- an asteroid collision.

While the causes of this global catastrophe are unknown, an MIT-led team of researchers has now established that the end-Permian extinction was extremely rapid, triggering massive die-outs both in the oceans and on land in less than 20,000 years -- the blink of an eye in geologic time. The researchers also found that this time period coincides with a massive buildup of atmospheric carbon dioxide, which likely triggered the simultaneous collapse of species in the oceans and on land.

With further calculations, the group found that the average rate at which carbon dioxide entered the atmosphere during the end-Permian extinction was slightly below today's rate of carbon dioxide release into the atmosphere due to fossil fuel emissions. Over tens of thousands of years, increases in atmospheric carbon dioxide during the Permian period likely triggered severe global warming, accelerating species extinctions.

The researchers also discovered evidence of simultaneous and widespread wildfires that may have added to end-Permian global warming, triggering what they deem "catastrophic" soil erosion and making environments extremely arid and inhospitable.

The researchers present their findings this week in Science, and say the new timescale may help scientists home in on the end-Permian extinction's likely causes.

For more information: http://web.mit.edu/newsoffice/2011/mass-extinction-1118.html

Source: NAI Newsletter

Posted by Keith Cowing at 12:07 PM | Permalink | Comments (0)

The Planetary Group, Department of Astronomy, University of Maryland, College Park has an immediate post-doctoral position opening in infrared spectral data analysis from the Deep Impact prime mission to Tempel 1 (Jul. 2005) and the extended mission's flyby of comet Hartley 2 (EPOXI; Nov. 2010).

Successful applicants will join a team of researchers at UMD working with Deep Impact and EPOXI and a group of planetary scientists whose projects span from dynamical studies to observational programs and who hold major roles in several planetary missions.

Prospective researchers should have a strong background in surface and/or gaseous spectroscopy in addition to knowledge of and experience with small body research and/or remote sensing. Successful applicants are expected to be versatile, have a strong and broad interest in planetary science, and have relevant experience as thesis research or as other post-doctoral activities.

The position is open immediately.  Starting dates in late 2011 are preferable.  The University of Maryland is an Equal Employment Opportunity and Affirmative Action Employer. Women and minority candidates are encouraged to apply.

Full text of the job description and application procedure is on the AAS Job Register: http://jobregister.aas.org/job_view?JobID=40095

Posted by Keith Cowing at 6:31 PM | Permalink | Comments (0)

Some asteroids may have been like "molecular factories" cranking out life's ingredients and shipping them to Earth via meteorite impacts. Now it appears that at least one asteroid may have been less like a rigid assembly line and more like a flexible diner that doesn't mind making changes to the menu.

Astrobiologists at NAI's Goddard Space Flight Center and Carnegie Institution of Washington teams studying the carbon-rich Tagish Lake meteorite have discovered that different pieces of it have greatly differing amounts of amino acids, the building blocks of proteins and essential ingredients to life as we know it.

In January, 2000, a large meteoroid exploded in the atmosphere over northern British Columbia, Canada, and rained fragments across the frozen surface of Tagish Lake. Because many people witnessed the fireball, pieces were collected within days and kept preserved in their frozen state. This ensured that there was very little contamination from terrestrial life.

"The Tagish Lake meteorite fell on a frozen lake in the middle of winter and was collected in a way to make it the best preserved meteorite in the world," said Dr. Christopher Herd of the University of Alberta, Edmonton, Canada, lead author of a paper about the analysis of the meteorite fragments published June 10 in the journal Science.

"The first Tagish Lake samples -- the ones we used in our study that were collected within days of the fall -- are the closest we have to an asteroid sample return mission in terms of cleanliness," adds Dr. Michael Callahan of NASA's Goddard Space Flight Center in Greenbelt, Md., a co-author on the paper.

Continue reading "Asteroid Served Up "Custom Orders" of Life's Ingredients" »

Posted by Keith Cowing at 12:40 AM | Permalink | Comments (0)

Some asteroids may have been like "molecular factories" cranking out life's ingredients and shipping them to Earth via meteorite impacts. Now it appears that at least one asteroid may have been less like a rigid assembly line and more like a flexible diner that doesn't mind making changes to the menu.

Astrobiologists at NAI's Goddard Space Flight Center and Carnegie Institution of Washington teams studying the carbon-rich Tagish Lake meteorite have discovered that different pieces of it have greatly differing amounts of amino acids, the building blocks of proteins and essential ingredients to life as we know it.

In January, 2000, a large meteoroid exploded in the atmosphere over northern British Columbia, Canada, and rained fragments across the frozen surface of Tagish Lake. Because many people witnessed the fireball, pieces were collected within days and kept preserved in their frozen state. This ensured that there was very little contamination from terrestrial life.

Continue reading "Asteroid Served Up "Custom Orders" of Life's Ingredients" »

Posted by Keith Cowing at 11:33 AM | Permalink | Comments (0)

Date/Time: Monday, March 28, 2011 11:00AM Pacific
Presenter: George Cody (Carnegie Institution of Washington)

Abstract:

Primitive bodies in the Solar System contain relatively large quantities of refractory organic macromolecular material. A lack of consensus exists as to the ultimate origin of these extraterrestrial organic solids stemming largely from the fact that throughout the Galaxy there exist many regions were extensive organo-synthesis occurs. Origins theories span from the lowest temperatures in the Interstellar Medium up to 1000 K in the inner Solar System. The best constraint on the origin of refractory organic solids is obtained by detailed studies of the organic material directly. Using advanced spectroscopic techniques we have identified a plausible source for these organic solids and show that the organic solids in both comets and carbonaceous chondrites share a common origin. The broader implications of these results, both in terms of our understanding of the early history of primitive Solar System objects and the origin of life on Earth, will be discussed.

For more information and participation instructions: http://astrobiology.nasa.gov/nai/seminars/detail/190

Source: NAI Newsletter

Posted by Keith Cowing at 10:28 PM | Permalink | Comments (0)

Join us for the second in a series of NASA Astrobiology Postdoctoral Program (NPP) seminars!

Date/Time: Monday, July 12th, 11am Pacific Time
Title: "Impact Bombardments on Early Earth and Mars: Implications for Habitability"
Speaker: Oleg Abramov, University of Colorado, Boulder

Abstract: Lunar rocks and impact melts, lunar and asteroidal meteorites, and an ancient martian meteorite record thermal metamorphic events with ages that group around and/or do not exceed 3.9 Gyr. That such a diverse suite of solar system materials share this feature is interpreted to be the result of a post-primary-accretion cataclysmic spike in the number of impacts commonly referred to as the late heavy bombardment (LHB). We report numerical models constructed to probe the degree of thermal metamorphism in the crust in the effort to recreate the effect of the LHB on the Earth and Mars; outputs were used to assess habitable volumes of crust for possible near-surface and subsurface primordial microbial biospheres. Our analysis shows that there is no plausible situation in which the habitable zone was fully sterilized on Earth and Mars, at least since the termination of primary accretion of the planets and the postulated impact origin of the Moon. Our results explain the root location of hyperthermophilic bacteria in the phylogenetic tree for 16S small-subunit ribosomal RNA, and bode well for the persistence of microbial biospheres even on planetary bodies strongly reworked by impacts. In fact, on Mars, the LHB may have been very beneficial for habitability by generating widespread hydrothermal activity, releasing water vapor into atmosphere, and likely temporarily changing global climate to a warmer and wetter state.

For more information and connection information: http://astrobiology.nasa.gov/nai/seminars/detail/178

Source: NAI Newsletter

Posted by Keith Cowing at 9:27 PM | Permalink | Comments (0)

NAI scientists from the University of Wisconsin Team and their colleagues have shown that the true age of this famous meteorite is 4.091 billion years, about 400 million years younger than earlier age estimates. Their study shows that it formed during a time when Mars was wet and had a magnetic field, conditions that are favorable for the emergence and development of life. This finding precludes ALH84001 from being a remnant of primordial Martian crust, as well as confirming that volcanic activity was ongoing in Mars over much of its history. Their paper appears in the April 16, 2010 issue of Science.

[Source: NAI Newsletter]

Posted by Keith Cowing at 5:55 PM | Permalink | Comments (0)

Dust samples collected by high-flying aircraft in the upper atmosphere have yielded an unexpectedly rich trove of relicts from the ancient cosmos, report scientists from NAI's Carnegie Institution of Washington team in Earth and Planetary Science Letters. The stratospheric dust includes minute grains that likely formed inside stars that lived and died long before the birth of our sun, as well as material from molecular clouds in interstellar space. This "ultra-primitive" material likely wafted into the atmosphere after the Earth passed through the trail of an Earth-crossing comet in 2003, giving scientists a rare opportunity to study cometary dust in the laboratory.

Continue reading "'Ultra-Primitive' Particles Found in Comet Dust" »

Posted by Keith Cowing at 10:16 PM | Permalink | Comments (0)

NASA scientists have discovered glycine, a fundamental building block of life, in samples of comet Wild 2 returned by NASA's Stardust spacecraft.

"Glycine is an amino acid used by living organisms to make proteins, and this is the first time an amino acid has been found in a comet," said Dr. Jamie Elsila of NASA's Goddard Space Flight Center in Greenbelt, Md. "Our discovery supports the theory that some of life's ingredients formed in space and were delivered to Earth long ago by meteorite and comet impacts."

Elsila is the lead author of a paper on this research accepted for publication in the journal Meteoritics and Planetary Science. The research will be presented during the meeting of the American Chemical Society at the Marriott Metro Center in Washington, DC, August 16.

Continue reading "NASA Researchers Make First Discovery of Life's Building Block in Comet" »

Posted by Keith Cowing at 9:55 PM | Permalink | Comments (0)

Members of the NAI community are cordially invited to submit abstracts to Session P13 of the AGU Fall Meeting in San Francisco in December. Conveners are seeking recent measurements, or experimental or theoretical results, relating to the relationship between structure and isotopic anomalies of the organic matter in extraterrestrial materials such as meteorites, IDPs, and Stardust samples.

For more information see http://www.agu.org/meetings/fm09/program/scientific_session_search.php?show=detail&sessid=401 Abstract Submissions will be open by July 30 and close September 3.

Posted by Keith Cowing at 11:36 PM | Permalink | Comments (0)

Comets are the deep freezers of dust and ices extant in the early solar nebula at the time of the formation of the giant planets. Astromineralogy is the study of the chemical and structural properties of the dust grains. Studying the dust mineralogy in comets and protoplanetary disks, and, in particular, the amorphous and crystalline silicates, probes the relative abundances of interstellar grains and grains thermally altered or condensed in the inner hot regions of disks, respectively. Research combines analysis and modeling of Spitzer and ground-based spectroscopy of comets as well as radiative transfer modeling of protoplanetary disks to further our understanding of the thermal processing and radial transport of dust in protoplanetary disks at the early epochs of planetesimal formation. Deadline: 5:00 PM EST February 1, 2009. http://fellowships.hq.nasa.gov/gsrp/research/detail.cfm?oppID=30

Posted by Keith Cowing at 9:42 AM | Permalink | Comments (0)

Nov 5 – 7, 2007, Kauai, HI

This interdisciplinary meeting is aimed at understanding the chronology of the processes in the early solar system as revealed by meteorites. This includes the astrophysical setting of solar system formation, the origin of short-lived radioisotopes, and the chronology of nebular and asteroidal processes: formation of chondrules, refractory inclusions and matrices of primitive chondrites, timing of accretion and thermal processing (aqueous alteration, thermal metamorphism, and igneous differentiation) of asteroids and comets.

For more information: http://www.lpi.usra.edu/meetings/metchron2007/metchron2007.1st.shtml [Source: NAI Newsletter]

Posted by Keith Cowing at 11:55 AM | Permalink | Comments (0)

August 13, 2009

A rehearsal flight of one of two aircraft will take off from Moffett Field to observe the Perseid meteor shower early on Monday, August 13. Scientists plan to carry their equipment onto the airplanes during the rehearsal and mission flights, without mounting the instruments within the aircraft.

Posted by Keith Cowing at 8:03 AM | Permalink | Comments (0)

In 83 B.C., a comet, now called Keiss, passed by the sun and ejected some bits of comet material. Astronomers expect the Aurigid meteor shower on Sept. 1, 2007, a result from Keiss comet’s earlier encounter with the sun in 83 B.C., to be spectacular.

Posted by Keith Cowing at 8:01 AM | Permalink | Comments (0)

A special issue of Science (Dec 15) includes several papers reporting on various aspects of Stardust sample analysis including an organics survey, isotopic and elemental compositions, mineralogy and petrology, and infrared spectroscopy. Many NAI researchers contributed to this comprehensive analytical campaign, including members of NAI's Teams at the Carnegie Institution of Washington, NASA's Ames Research Center and Goddard Space Flight Center, and NAI's Alumni Team at the University of Washington. [Source: NAI Newsletter]

Posted by Keith Cowing at 1:22 AM | Permalink | Comments (0)

Follow along as scientists from NAI's University of Hawai'i Team go on expedition with the NSF/NASA-sponsored Antarctic Search for Meteorites (ANSMET) program. View photos, read about the team and their mission, and stay current with regular dispatches from the "Streets of McMurdo."

Continue reading "AI Researchers Search for Meteorites in Antarctica" »

Posted by Keith Cowing at 12:22 AM | Permalink | Comments (0)

Researchers from NAI's NASA Goddard Space Flight Center Team and their colleagues publish their analysis of two meteorites in the current issue of Meteoritics and Planetary Science. Their study revealed a suite of amino acids present in the meteorites that are not present in the Antarctic ice on which they were found. [Source: NAI Newsletter]

Posted by Keith Cowing at 10:53 AM | Permalink | Comments (0)

The Center for Meteorite Studies at Arizona State University is pleased to announce the 40th Anniversary of the Nininger Award for undergraduate and graduate students pursuing research in meteoritical sciences.

Continue reading "ASU Award for Students Pursuing Research in Meteoritical Sciences" »

Posted by Keith Cowing at 12:34 AM | Permalink | Comments (0)