Mostrando entradas con la etiqueta Meteorite. Mostrar todas las entradas
Mostrando entradas con la etiqueta Meteorite. Mostrar todas las entradas

domingo, 6 de enero de 2013

NASA - Researchers Identify Water Rich Meteorite Linked To Mars Crust


http://www.nasa.gov/images/content/716969main_black_beauty_full.jpg
Designated Northwest Africa (NWA) 7034, and nicknamed "Black Beauty," the Martian meteorite weighs approximately 11 ounces (320 grams). Credit: NASA
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Researchers Identify Water Rich Meteorite Linked to Mars Crust.-
WASHINGTON -- NASA-funded researchers analyzing a small meteorite that may be the first discovered from the Martian surface or crust have found it contains 10 times more water than other Martian meteorites from unknown origins.

This new class of meteorite was found in 2011 in the Sahara Desert. Designated Northwest Africa (NWA) 7034, and nicknamed "Black Beauty," it weighs approximately 11 ounces (320 grams). After more than a year of intensive study, a team of U.S. scientists determined the meteorite formed 2.1 billion years ago during the beginning of the most recent geologic period on Mars, known as the Amazonian.

"The age of NWA 7034 is important because it is significantly older than most other Martian meteorites," said Mitch Schulte, program scientist for the Mars Exploration Program at NASA Headquarters in Washington. "We now have insight into a piece of Mars' history at a critical time in its evolution."

The meteorite is an excellent match for surface rocks and outcrops NASA has studied remotely via Mars rovers and Mars-orbiting satellites. NWA 7034's composition is different from any previously studied Martian meteorite. The research is published in Thursday's edition of Science Express.

"The contents of this meteorite may challenge many long held notions about Martian geology," said John Grunsfeld, associate administrator for NASA's Science Mission Directorate in Washington. "These findings also present an important reference frame for the Curiosity rover as it searches for reduced organics in the minerals exposed in the bedrock of Gale Crater."

NWA 7034 is made of cemented fragments of basalt, rock that forms from rapidly cooled lava. The fragments are primarily feldspar and pyroxene, most likely from volcanic activity. This unusual meteorite's chemistry matches that of the Martian crust as measured by NASA's Mars Exploration Rovers and Mars Odyssey Orbiter.

"This Martian meteorite has everything in its composition that you'd want in order to further our understanding of the Red Planet," said Carl Agee, leader of the analysis team and director and curator at the University of New Mexico's Institute of Meteoritics in Albuquerque. "This unique meteorite tells us what volcanism was like on Mars 2 billion years ago. It also gives us a glimpse of ancient surface and environmental conditions on Mars that no other meteorite has ever offered."

The research team included groups at the University of California at San Diego and the Carnegie Institution in Washington. Experiments were conducted to analyze mineral and chemical composition, age, and water content.

Researchers theorize the large amount of water contained in NWA 7034 may have originated from interaction of the rocks with water present in Mars' crust. The meteorite also has a different mixture of oxygen isotopes than has been found in other Martian meteorites, which could have resulted from interaction with the Martian atmosphere.

Most Martian meteorites are divided into three rock types, named after three meteorites; Shergotty, Nakhla, and Chassigny. These "SNC" meteorites currently number about 110. Their point of origin on Mars is not known and recent data from lander and orbiter missions suggest they are a mismatch for the Martian crust. Although NWA 7034 has similarities to the SNC meteorites, including the presence of macromolecular organic carbon, this new meteorite has many unique characteristics.

"The texture of the NWA meteorite is not like any of the SNC meteorites," said co-author Andrew Steele, who led the carbon analysis at the Carnegie Institution's Geophysical Laboratory. "This is an exciting measurement in Mars and planetary science. We now have more context than ever before to understanding where they may come from."

The research was funded by NASA's Cosmochemistry Program and Astrobiology Institute, part of the Planetary Science Division in the Science Mission Directorate at NASA Headquarters. The research also was supported by the New Mexico Space Grant Consortium in Las Cruces, and the National Science Foundation in Arlington, Va.

To see an image of NWA 7034, visit:
NASA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@gmail.com
ayabaca@hotmail.com
ayabaca@yahoo.com
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miércoles, 3 de octubre de 2012

Comet crystals found in a nearby planetary system



 Close-up of olivine crystals seen inside a meteorite found on Earth that originated from a partly melted Solar System asteroid. The yellow olivine crystals are on the order of a few millimetres to centimetres in size and are held together by an alloy of iron and nickel. In contrast, the olivine crystals found in pristine comets, such as in the material measured in the Beta Pictoris system by ESA’s Herschel space observatory, are iron-poor but magnesium-rich.

Credits: J. Debosscher, KU Leuven


Olivine crystals

Comet crystals found in a nearby planetary system
3 October 2012
Pristine material that matches comets in our own Solar System have been found in a dust belt around the young star Beta Pictoris by ESA’s Herschel space observatory.

Twelve-million-year-old Beta Pictoris resides just 63 light-years from Earth and hosts a gas giant planet along with a dusty debris disc that could, in time, evolve into a torus of icy bodies much like the Kuiper Belt found outside the orbit of Neptune in our Solar System.
Thanks to the unique observing capabilities of Herschel, the composition of the dust in the cold outskirts of the Beta Pictoris system has been determined for the first time.
Of particular interest was the mineral olivine, which crystallises out of the protoplanetary disc material close to newborn stars and is eventually incorporated into asteroids, comets and planets.
“As far as olivine is concerned, it comes in different ‘flavours’,” explains Ben de Vries from KU Leuven and lead author of the study reported in Nature.
“A magnesium-rich variety is found in small and primitive icy bodies like comets, whereas iron-rich olivine is typically found in large asteroids that have undergone more heating, or ‘processing’.”
Infrared view of the Beta Pictoris solar system, obtained by combining data from the ADONIS instrument on ESO’s 3.6 m telescope (outer regions) and the NACO instrument on one of the 8.2 m units of ESO’s Very Large Telescope (inner region), and then subtracting the overpowering glare of the central star. The image shows a planet orbiting at roughly the same distance from Beta Pictoris as Saturn is from our own Sun, and a prominent dust disc in the outer reaches of the system. New observations from ESA’s Herschel space telescope have found magnesium-rich olivine crystals in the disc that likely originated from collisions between comets: the dust shares the same compositional characteristics as in several comets in our Solar System. Furthermore, the observation of these olivines in the outer dust disc suggest that they have been transported from their birthplace close to the central star, since they cannot form under the cold conditions found further out.

Credits: ESO/A-M. Lagrange et al.

 Herschel detected the pristine magnesium-rich variety in the Beta Pictoris system at 15–45 astronomical units (AUs) from the star, where temperatures are around –190ºC.
For comparison, Earth lies at 1 AU from our Sun and the Solar System’s Kuiper Belt extends from the orbit of Neptune at about 30 AU out to 50 AU from the Sun.
The Herschel observations allowed astronomers to calculate that the olivine crystals make up around 4% of the total mass of the dust found in this region.
In turn, this finding led them to conclude that the olivine was originally bound up inside comets and released into space by collisions between the icy objects.
“The 4% value is strikingly similar to that of Solar System comets 17P/Holmes and 73P/Schwassmann-Wachmann 3, which contain 2–10% magnesium-rich olivine,” says Dr de Vries.
“Since olivine can only crystallise within about 10 AU of the central star, finding it in a cold debris disc means that it must have been transported from the inner region of the system to the outskirts.”
The ‘radial mixing’ transport mechanism is known from models of the evolution of swirling protoplanetary discs as they condense around new stars.
The mixing is stimulated in varying amounts by winds and heat from the central star pushing materials away, along with temperature differences and turbulent motion created in the disc during planet formation.
“Our findings are an indication that the efficiency of these transport processes must have been similar between the young Solar System and within the Beta Pictoris system, and that these processes are likely independent of the detailed properties of the system,” says Dr de Vries.
Indeed, Beta Pictoris is over one and a half times the mass of our Sun, eight times as bright, and its planetary system architecture is different to our own Solar System today.
“Thanks to Herschel, we were able to measure the properties of pristine material left over from the initial planet-building process in another solar system with a precision that is comparable to what we could achieve in the laboratory if we had the material here on Earth,” says ESA’s Herschel project scientist Göran Pilbratt.


Notes for Editors
 ESA
Guillermo Gonzalo Sánchez Achutegui
ayabaca@hotmail.com
ayabaca@gmail.com
ayabaca@yahoo.com
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