Meteorite holds clues to organic chemistry of early Earth

ScienceDaily (June 9, 2011) — Carbonaceous chondrites are a type of organic-rich meteorite that contain samples of the materials that took part in the creation of our planets nearly 4.6 billion years ago, including materials that were likely formed before our Solar System was created and may have been crucial to the formation of life on Earth. The complex suite of organic materials found in carbonaceous chondrites can vary substantially from meteorite to meteorite.

New research from Carnegie's Department of Terrestrial Magnetism and Geophysical Laboratory, published June 10 in Science, shows that most of these variations are the result of hydrothermal activity that took place within a few million years of the formation of the Solar System, when the meteorites were still part of larger parent bodies, likely asteroids.

Organic material in carbonaceous chondrites shares many characteristics with organic matter found in other primitive samples, including interplanetary dust particles, comet 81P/Wild-2, and Antarctic micrometeorites. It has been argued by some that this similarity indicates that organic material throughout the Solar System largely originated from a common source, possibly the interstellar medium.

A test of this common-source hypothesis stems from its requirement that the organic diversity within and among meteorites be due primarily to chemical and thermal processing that took place while the meteorites were parts of their parent bodies. In other words, there should be a relationship between the extent of hydrothermal alteration that a meteorite experienced and the chemistry of the organic material it contains.

If--as many have speculated--the organic material in meteorites had a role to play in the origin of life on Earth, the attraction of the common-source hypothesis is that the same organic material would have been delivered to all bodies in the Solar System. If the common source was the interstellar medium, then similar material would also be delivered to any forming planetary system.

The research team -- led by Christopher Herd of the University of Alberta, Canada, and including Carnegie's Conel Alexander, Larry Nittler, Frank Gyngard, George Cody, Marilyn Fogel, and Yoko Kebukawa -- studied four meteorite specimens from the shower of stones, produced by the breakup of a meteoroid as it entered the atmosphere, that fell on Tagish Lake in northern Canada in January 2000. The samples are considered very pristine, because they fell on a frozen lake, were collected without hand contact within a few days of landing and have remained frozen ever since.

The samples were processed and analyzed on the microscopic level using a variety of sophisticated techniques. Examination of their inorganic components indicated that the specimens had experienced large differences in the extent of hydrothermal alteration, prompting an in-depth examination of their organic material. The team demonstrated that the insoluble organic matter found in the samples has properties that span nearly the entire range found in all carbonaceous chondrites and that those properties correlate with other measures of the extent of parent body alteration. Their finding confirms that the diversity of this material is due to processing of a common precursor material in the asteroidal parent bodies.

The team found large concentrations of monocarboxylic acids, or MCAs, which are essential to biochemistry, in their Tagish Lake samples. They attributed the high level of these acids to the pristine nature of the samples, which have been preserved below zero degrees Celsius since they were recovered. There was variety in the types of MCAs, which they determined could also be due to alterations that took place on the parent bodies.

The samples also contained amino acids -- the essential-for-life organic building blocks used to create proteins. The types and abundances of amino acids contained in the samples are consistent with an extraterrestrial origin, and were clearly also influenced, albeit in a complex way, by the alteration histories of their host meteorites.

"Taken together these results indicate that the chemical and thermal processing common to the Tagish Lake meteorites likely occurred when the samples were part of a larger parent body that was created from the same raw materials that formed our Solar System," said Larry Nittler of Carnegie's DTM. "These samples can also provide important clues to the source of organic material, and life, on Earth."

Funding was provided by Natural Sciences and Engineering Research Council of Canada, Alberta Innovates, NASA (Astrobiology, including NASA Astrobiology Institute teams at the Carnegie Institution and the Goddard Center for Astrobiology; Origins of Solar Systems; Cosmochemistry and Postdoctoral Programs), the U.S. Office of Naval Research, Carnegie Institution for Science, Grant MacEwan University, and the Carnegie Institution of Canada. Some data was acquired at Advanced Light Source, which is supported by the Director of the Office of Science, Department of Energy, and by a W.M. Keck Foundation grant to the Carnegie Institution for Science.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Carnegie Institution, via EurekAlert!, a service of AAAS.

Journal Reference:

Christopher D. K. Herd, Alexandra Blinova, Danielle N. Simkus, Yongsong Huang, Rafael Tarozo, Conel M. O’D. Alexander, Frank Gyngard, Larry R. Nittler, George D. Cody, Marilyn L. Fogel, Yoko Kebukawa, A. L. David Kilcoyne, Robert W. Hilts, Greg F. Slater, Daniel P. Glavin, Jason P. Dworkin, Michael P. Callahan, Jamie E. Elsila, Bradley T. De Gregorio, Rhonda M. Stroud. Origin and Evolution of Prebiotic Organic Matter As Inferred from the Tagish Lake Meteorite. Science, 2011; 332 (6035): 1304-1307 DOI: 10.1126/science.1203290

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Meteorite holds clues to organic chemistry of early Earth

ScienceDaily (June 9, 2011) — Carbonaceous chondrites are a type of organic-rich meteorite that contain samples of the materials that took part in the creation of our planets nearly 4.6 billion years ago, including materials that were likely formed before our Solar System was created and may have been crucial to the formation of life on Earth. The complex suite of organic materials found in carbonaceous chondrites can vary substantially from meteorite to meteorite.

New research from Carnegie's Department of Terrestrial Magnetism and Geophysical Laboratory, published June 10 in Science, shows that most of these variations are the result of hydrothermal activity that took place within a few million years of the formation of the Solar System, when the meteorites were still part of larger parent bodies, likely asteroids.

Organic material in carbonaceous chondrites shares many characteristics with organic matter found in other primitive samples, including interplanetary dust particles, comet 81P/Wild-2, and Antarctic micrometeorites. It has been argued by some that this similarity indicates that organic material throughout the Solar System largely originated from a common source, possibly the interstellar medium.

A test of this common-source hypothesis stems from its requirement that the organic diversity within and among meteorites be due primarily to chemical and thermal processing that took place while the meteorites were parts of their parent bodies. In other words, there should be a relationship between the extent of hydrothermal alteration that a meteorite experienced and the chemistry of the organic material it contains.

If--as many have speculated--the organic material in meteorites had a role to play in the origin of life on Earth, the attraction of the common-source hypothesis is that the same organic material would have been delivered to all bodies in the Solar System. If the common source was the interstellar medium, then similar material would also be delivered to any forming planetary system.

The research team -- led by Christopher Herd of the University of Alberta, Canada, and including Carnegie's Conel Alexander, Larry Nittler, Frank Gyngard, George Cody, Marilyn Fogel, and Yoko Kebukawa -- studied four meteorite specimens from the shower of stones, produced by the breakup of a meteoroid as it entered the atmosphere, that fell on Tagish Lake in northern Canada in January 2000. The samples are considered very pristine, because they fell on a frozen lake, were collected without hand contact within a few days of landing and have remained frozen ever since.

The samples were processed and analyzed on the microscopic level using a variety of sophisticated techniques. Examination of their inorganic components indicated that the specimens had experienced large differences in the extent of hydrothermal alteration, prompting an in-depth examination of their organic material. The team demonstrated that the insoluble organic matter found in the samples has properties that span nearly the entire range found in all carbonaceous chondrites and that those properties correlate with other measures of the extent of parent body alteration. Their finding confirms that the diversity of this material is due to processing of a common precursor material in the asteroidal parent bodies.

The team found large concentrations of monocarboxylic acids, or MCAs, which are essential to biochemistry, in their Tagish Lake samples. They attributed the high level of these acids to the pristine nature of the samples, which have been preserved below zero degrees Celsius since they were recovered. There was variety in the types of MCAs, which they determined could also be due to alterations that took place on the parent bodies.

The samples also contained amino acids -- the essential-for-life organic building blocks used to create proteins. The types and abundances of amino acids contained in the samples are consistent with an extraterrestrial origin, and were clearly also influenced, albeit in a complex way, by the alteration histories of their host meteorites.

"Taken together these results indicate that the chemical and thermal processing common to the Tagish Lake meteorites likely occurred when the samples were part of a larger parent body that was created from the same raw materials that formed our Solar System," said Larry Nittler of Carnegie's DTM. "These samples can also provide important clues to the source of organic material, and life, on Earth."

Funding was provided by Natural Sciences and Engineering Research Council of Canada, Alberta Innovates, NASA (Astrobiology, including NASA Astrobiology Institute teams at the Carnegie Institution and the Goddard Center for Astrobiology; Origins of Solar Systems; Cosmochemistry and Postdoctoral Programs), the U.S. Office of Naval Research, Carnegie Institution for Science, Grant MacEwan University, and the Carnegie Institution of Canada. Some data was acquired at Advanced Light Source, which is supported by the Director of the Office of Science, Department of Energy, and by a W.M. Keck Foundation grant to the Carnegie Institution for Science.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by Carnegie Institution, via EurekAlert!, a service of AAAS.

Journal Reference:

Christopher D. K. Herd, Alexandra Blinova, Danielle N. Simkus, Yongsong Huang, Rafael Tarozo, Conel M. O’D. Alexander, Frank Gyngard, Larry R. Nittler, George D. Cody, Marilyn L. Fogel, Yoko Kebukawa, A. L. David Kilcoyne, Robert W. Hilts, Greg F. Slater, Daniel P. Glavin, Jason P. Dworkin, Michael P. Callahan, Jamie E. Elsila, Bradley T. De Gregorio, Rhonda M. Stroud. Origin and Evolution of Prebiotic Organic Matter As Inferred from the Tagish Lake Meteorite. Science, 2011; 332 (6035): 1304-1307 DOI: 10.1126/science.1203290

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here

Moon's rough 'wrinkles' reveal clues to its past

ScienceDaily (May 15, 2011) — Written on the moon's weary face are the damages it has endured for the past 4-1/2 billion years. From impact craters to the dark plains of maria left behind by volcanic eruptions, the scars are all that remain to tell the tale of what happened to the moon. But they only hint at the processes that once acted -- and act today -- to shape the surface.

To get more insight into those processes, Meg Rosenburg and her colleagues at the California Institute of Technology, Pasadena, Calif. put together the first comprehensive set of maps revealing the slopes and roughness of the moon's surface. These maps are based on detailed data collected by the Lunar Orbiter Laser Altimeter (LOLA) on NASA's Lunar Reconnaissance Orbiter. LOLA and LRO were built at NASA's Goddard Space Flight Center in Greenbelt, Md.

Like wrinkles on skin, the roughness of craters and other features on the moon's surface can reveal their age. "The key is to look at the roughness at both long and short scales," says Rosenburg, who is the first author on the paper describing the results, published in the Journal of Geophysical Research earlier this year.

The roughness depends on the subtle ups and downs of the landscape, a quality that the researchers get at by measuring the slope at locations all over the surface. To put together a complete picture, the researchers looked at roughness at a range of different scales -- the distances between two points -- from 17 meters (about 56 feet) to as much as 2.7 kilometers (about 1.6 miles).

"Old and young craters have different roughness properties -- they are rougher on some scales and smoother on others," says Rosenburg. That's because the older craters have been pummeled for eons by meteorites that pit and mar the site of the original impact, changing the original shape of the crater.

"Because this softening of the terrain hasn't happened at the new impact sites, the youngest craters immediately stand out," says NASA Goddard's Gregory Neumann, a co-investigator on LOLA.

"It is remarkable that the moon exhibits a great range of topographic character: on the extremes, surfaces roughened by the accumulation of craters over billions of years can be near regions smoothed and resurfaced by more recent mare volcanism," says Oded Aharonson, Rosenburg's advisor at the California Institute of Technology.

By looking at where and how the roughness changes, the researchers can get important clues about the processes that shaped the moon. A roughness map of the material surrounding Orientale basin, for example, reveals subtle differences in the ejecta, or debris, that was thrown out when the crater was formed by a giant object slamming into the moon.

That information can be combined with a contour map that shows where the high and low points are. "By looking at both together, we can say that one part of Orientale is not just higher or lower, it's also differently rough," Rosenburg says. "That gives us some clues about the impact process that launched the ejecta and also about the surface processes that later acted to modify it."

Likewise, the smooth plains of maria, which were created by volcanic activity, have a different roughness "signature" from the moon's highlands, reflecting the vastly different origins of the two terrains. Maria is Latin for "seas," and they got that name from early astronomers who mistook them for actual seas.

Just as on the moon, the same approach can be used to study surface processes on other bodies as well, Rosenburg says. "The processes at work are different on Mars than they are on an asteroid, but they each leave a signature in the topography for us to interpret. By studying roughness at different scales, we can begin to understand how our nearest neighbors came to look the way they do."

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by NASA/Goddard Space Flight Center.

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

View the original article here