Recently in the Meteorites, Asteroids, & Comets Category


A team of scientists at NASA's Johnson Space Center in Houston and the Jet Propulsion Laboratory in Pasadena, Calif., has found evidence of past water movement throughout a Martian meteorite, reviving debate in the scientific community over life on Mars.

The class of meteorites called carbonaceous chondrites are examples of material from the solar system which have been relatively unchanged from the time of their initial formation.

While the origin of life remains mysterious, scientists are finding more and more evidence that material created in space and delivered to Earth by comet and meteor impacts could have given a boost to the start of life.

The water found on the moon, like that on Earth, came from small meteorites called carbonaceous chondrites in the first 100 million years or so after the solar system formed, researchers from Brown and Case Western Reserve universities and Carnegie Institution of Washington have found.

In an effort to determine if conditions were ever right on Mars to sustain life, a team of scientists, including a Michigan State University professor, has examined a meteorite that formed on the red planet more than a billion years ago. And although this team's work is not specifically solving the mystery, it is laying the groundwork for future researchers to answer this age-old question.

The Astromaterials Research and Exploration Science (ARES) Directorate, NASA Johnson Space Center (JSC), anticipates an opening for a civil service research scientist in the Astromaterials Research Office. The incumbent will be expected to conduct fundamental research in the general area of organic geochemistry of astromaterials. United States citizenship and a Ph.D. or equivalent experience in chemistry, physics, geology, geochemistry, planetary sciences, or a related field are required. The position requires an advanced knowledge of principles, practices, and applications of organic geochemistry in planetary and space sciences. The position will be filled at the GS-13 level. For a table of civil servant salaries in the greater Houston area, see http://www.opm.gov/oca/12tables/html/hou.asp

The selectee will be expected to establish a strong research program and to attract funds from any of the range of NASA Research & Analysis programs. This research program should complement or build upon existing ARES strengths, which include studies of primitive materials, meteorites, comets, and asteroids; Mars exploration and science research; experimental studies; and astrobiology. ARES is well-equipped with state of the art analytical and experimental laboratories (see http://ares.jsc.nasa.gov/ares/index_krlab.cfm for a complete list). Participation in NASA-sponsored space science missions is strongly encouraged (e.g. instrument team member/PI/co-I, participating scientist, etc.). Finally, the selectee will provide advice and support to the ARES Astromaterials Acquisition and Curation Office for issues relating to organic geochemistry, such as organic contamination control, planetary protection, and procedures for appropriate curation of astromaterials that may contain organic species, on an as-needed basis up to approximately one-fifth time.

It is anticipated that the official position announcement will appear on or about 1 September 2012. All applications must be made through the USAJobs.gov website. The formal announcement will contain details on the application process, including dates the position will be open for application. Starting date is subject to negotiation. Please address inquiries to Dr. David Draper (Manager, Astromaterials Research Office, David Draper), who will also provide, upon request, a detailed outline (authored by JSC's Human Resources office) for navigating the USAJobs.gov website and compiling a responsive application. [Source: NAI]

Cometary Composition in Review

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

Timeline of a Mass Extinction

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

Post-doctoral Position in Cometary Science

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

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.