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Topic: ALH84001


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  ALH84001 - Wikipedia, the free encyclopedia
ALH84001 (Allen Hills, 1984 #001) is a meteorite found in Allen Hills, Antarctica in December 1984 by a team of US meteorite hunters from the ANSMET project.
Like other members of the group of SNCs (shergottite, nakhlite, chassignite), ALH84001 is almost certainly from Mars, shocked and broken by one or more meteorite impacts some 3.6 billion years ago, and blasted off of the surface of Mars in a separate impact about 15 million years ago.
In September 2005, Vicky Hamilton of the University of Hawaii at Manoa presented an analysis of the origin of ALH84001 using data from the Mars Global Surveyor and Mars Odyssey spacecraft orbiting Mars.
en.wikipedia.org /wiki/ALH84001   (556 words)

  
 Science on-Line David S. McKay, et al., Science 273(5277):924
ALH84001 arrived on Earth 13,000 years ago (15, 21) and appears to be essentially free of terrestrial weathering (8).
ALH84001 does not have the carbon isotopic compositions typically associated with weathered meteorites (12, 15), and detailed mineralogical studies (8) show that ALH84001 has not been significantly affected by terrestrial weathering processes.
Magnetite particles in ALH84001 are similar (chemically, structurally, and morphologically) to terrestrial magnetite particles known as magnetofossils (45), which are fossil remains of bacterial magnetosomes (46) found in a variety of sediments and soils (41, 47, 48) and classified as single-domain (20 to 100 nm) or superparamagnetic (<20 nm) magnetite (49).
zebu.uoregon.edu /~imamura/talks/mars/924.html   (6491 words)

  
 Allan Hills Meteorite Abiogenic? :: Astrobiology Magazine :: Search for Life in the Universe
In the recent study, a team of scientists based largely at JSC found that a mineral in Mars meteorite ALH84001 that had been asserted to be most likely caused by an ancient microscopic organism may have been caused by a non-biological process.
The new paper reports that magnetite, an iron-bearing mineral found in Martian meteorite ALH84001, was likely caused by inorganic processes, and that those same processes can be recreated in the laboratory, forming magnetite identical to that found in the Mars meteorite.
ALH84001 was discovered in 1984 in the Allan Hills region of Antarctica by an annual expedition of the National Science Foundation's Antarctic Meteorite Program.
www.astrobio.net /news/modules.php?op=modload&name=News&file=article&sid=1090&mode=thread&order=0&thold=0   (964 words)

  
 Astrobiology for Teachers
ALH84001 is one of how many meteorites found on Earth that are thought to have come from Mars?
Describe the isotopic evidence that suggests that ALH84001 (and the other martian meteorites) is a martian meteorite.
Describe the precautionary steps (from the time it was collected to the actual testing of the meteorite) that were taken to ensure that ALH84001 was not contaminated.
btc.montana.edu /ceres/astrobiology/files/chapter9.html   (376 words)

  
 Wikinfo | ALH84001   (Site not responding. Last check: 2007-11-07)
ALH84001 is the designation of a meteorite fragment, generally regarded as originating on Mars.
It was discovered in December 1984 in Antarctica by a meteorite-search expedition of the ANSMET program, as one of 7000 others.
ALH84001 became known because of certain microscopic structures that were for some time considered to be the remains of bacteria-like lifeforms.
www.wikinfo.org /wiki.php?title=ALH84001   (239 words)

  
 NAI News Article: Taking the Temperature of a Martian Meteorite   (Site not responding. Last check: 2007-11-07)
ALH84001 was blasted off of Mars 15 million years ago, most likely by an asteroid or comet impact.
Microscopic shapes in the carbonate globules of ALH84001 resemble fossil bacteria on Earth, and the meteorite seems to have the same microscopic mineral grains that are produced by bacteria.
Weiss and his colleagues are now working on a variety of paleomagnetic problems related to the evolution of life and planetary bodies such as Mars, Earth, and the moon.
nai.arc.nasa.gov /news_stories/news_print.cfm?ID=176   (1646 words)

  
 Creation Matters Mar/Apr 1997, Vol.2, No.2
The second shock experienced by ALH84001, 8 to 15 Ma, is evidenced by: the formation of maskelynite from plagioclase; microfault offsets cutting silicates, oxides, and carbonates; and radial cracks around maskelynite and chromite grains.
The PAH composition of ALH84001 is similar to the organic molecular composition of carbonaceous chondrite meteorites whose abiotic origin is commonly accepted.
If the alleged ALH84001 nanofossils are in fact high temperature asymmetrical magnetite crystals, these findings cast a dark shadow on the likelihood of a biological origin of several of the components of the meteorite.
www.creationresearch.org /creation_matters/97/cm9703.html   (3871 words)

  
 Features of ALH84001   (Site not responding. Last check: 2007-11-07)
The meteorite ALH84001 is a chunk of igneous rock, very similar to terrestrial rocks which are formed by solidification of volcanic lava.
The largest unusual features of ALH84001 are a large number of small globules of carbonate minerals, ranging from 1 micron (0.001 mm) to 250 microns (1/4 mm) across.
The concentration of PAH's is largest where the carbonate globules are, except that the concentration is very low near the outer skin of the meteorite -- the part that would have melted when it fell through the atmosphere 13,000 years ago.
www.ndsu.nodak.edu /instruct/kurtze/phys110/news/marslife/features.htm   (521 words)

  
 Interpreting the features of ALH84001
The ovoid objects found near the center of the carbonate globules resemble similar features found on some fossil rocks from southern Italy, which are generally accepted to be fossils of ancient "nanobacteria", the smallest known terrestrial bacteria.
Finally, the overall structure of the carbonate globules is similar to that of carbonate bundles produced by terrestrial bacteria both in the laboratory and in freshwater ponds.
On Earth, the first carbonates to be produced (which therefore are near the center of the bundle) contain manganese; followed by iron carbonate, and finally a burst of iron sulfides (which would be found near the rim, which is the last part of the bundle to form).
www.ndsu.nodak.edu /instruct/kurtze/phys110/news/marslife/meaning.htm   (948 words)

  
 Life on Mars? Did it Come from Earth?. Origins & Design 18:1. Yockey, Hubert P.
He discussed briefly the history of ALH84001 from its formation four billion years ago on Mars, its escape as a consequence of the shock from the impact of a body striking Mars, the 16 million-year journey through space and its arrival 13, 000 years ago on a glacier in Antarctica.
ALH84001 is an igneous orthopyroxenite, not a sedimentary rock.
To assert that ALH84001 exhibits evidence for life is to ignore genetics17 and accept Oparinism3.
www.arn.org /docs/odesign/od181/mars181.htm   (3383 words)

  
 Planetary Protection at NASA
A comparison of ALH84001 and an Antarctic meteorite from the Moon showed similar "microfossil" features on both, suggesting that the "microfossils" are terrestrial [45].
The shapes of the ALH84001 magnetite grains may not be the same as those in the target MV-1 bacterium [29,30,32], and the distribution of magnetite sizes is significantly different [24].
On the other hand, nearly all the data on ALH84001 and on Earth life developed since 1996 is not consistent with the claims, arguments, and hypothesis of McKay et al.
planetaryprotection.nasa.gov /pp/summaries/alh84001.htm   (3211 words)

  
 Hitchhiking on a Meteorite: Is there Mars Life on Earth? | SpaceRef - Your Space Reference
Regardless of where you sit on this debate, it is important to note that the announcement spurred many to revisit a tantalizing thought many thought had been put to rest 20 years earlier: the possibility that live may have existed on Mars.
Humans first encountered (and named) ALH84001 in 1984 when it was picked up off of the surface in the Allan Hills (hence the "ALH") region of Antarctica by an ANSMET (ANtarctic Search for METeorites) expedition.
ALH84001 then languished in a collection container until some years later when a mineralogical analysis - and comparison with SNC meteorites - showed enough similarities to conclude that it was from Mars.
www.spaceref.com /news/viewnews.html?id=457   (3031 words)

  
 Martian meteorite: ALH84001   (Site not responding. Last check: 2007-11-07)
This meteorite, named ALH84001, was recovered in Antarctica in 1984 and later determined to have originated on Mars.
ALH84001 is especially important because it contains some evidence for ancient fossil life on Mars.
ALH84001 provides a good recent example of the debate and critical testing of ideas that is typical of science.
tycho.bgsu.edu /~laird/cp_images/alh84001.html   (227 words)

  
 ALH 84001: Recent Scientific Papers   (Site not responding. Last check: 2007-11-07)
Given that ALH84001 laid on the Earth’s surface for thousands of years and is infested with terrestrial microbes (Steele et al., 1999), the cautious mind will infer that the filament and biofilm are terrestrial until proven otherwise.
This sequence of minerals is similar to that in the ALH84001 globules: calcite, ankerite, magnesian siderite, and magnesite.
The carbonates globules in ALH84001 differ from known terrestrial evaporite deposits in several respects: some of their carbonates are rich in iron; their magnesite is rich in calcium; sulfate minerals are nearly absent; and they have layers rich in magnetite.
www.lpi.usra.edu /lpi/meteorites/alhnpap.html   (15761 words)

  
 PSR Discoveries:Hot Idea: Martian Organic Matter in ALH84001   (Site not responding. Last check: 2007-11-07)
Using only 0.46 grams of ALH84001, they carried out a series of experiments in which they dissolved the carbonates, a main carrier of organic compounds, and measured the carbon isotopic compositions of the solutions and the left over, undissolved rock.
This similarity leads Becker and coworkers to suggest that the indigenous organic compounds in ALH84001 may be from meteorite bombardment of the surface of Mars.
Whether the organic compounds in ALH 84001 are biological or not, this work, coupled with Jull's observation that 20% of the organic compounds in ALH84001 could be extraterrestrial, shows that organic compounds are present on Mars.
www.psrd.hawaii.edu /June99/organicsBecker.html   (592 words)

  
 Astrobiology at Macalester-Arguments For Life On Mars
The carbonate found in the Martian meteorite ALH84001 was surrounded by microscopic features interpreted as fossils by the scientists studying the meteorite.
This indicates that the PAHs found in ALH84001 were not formed through the decay of Earth organisms that found their way into the meteorite.
Life on Earth is known to survive temperatures of up to at least 120 ° F. Thus, though the original theory citing bacteria as the producer of various features in ALH84001 was not an equilibrium model, the presence of life in the rock is still a possibility.
www.macalester.edu /astronomy/research/sonya/forlife.html   (750 words)

  
 It's dead Jim. But was it ever alive?
The structure of ALH84001 (cracks and pores) raises the possibility that the rock could have harbored water-born microbial cells and colonies introduced long after the rock cooled, a process which has been shown to happen on Earth.
Structures occur in the rims of the carbonate globules found within ALH84001 that are similar in size and shape to the mineralized casts of modern terrestrial bacteria, their appendages, and by-products.
The stable isotope patterns within ALH84001 have shown the presence of indigenous carbon components that have isotopic signatures in the direction of known biogenic carbon signatures.
www.astrobiology.com /adastra/its.dead.jim.html   (2448 words)

  
 Mars Meteorite   (Site not responding. Last check: 2007-11-07)
The recent discovery of possible relic nanobacteria in carbonate concretions in the Martian meteorite ALH84001 represents the first potential demonstration of life elsewhere than on Earth.
The ALH84001 meteorite is composed dominantly of orthopyroxene with minor clinopyroxene, olivine, chromite, pyrite, apatite, shocked feldspathic glass and SiO2.The sample is highly fractured, probably by impact events, and secondary carbonates occur in some fractures as disk-shaped concretions typically hundreds of microns in diameter.
Although results strongly support the low temperature genesis of the carbonate concretions, the precise temperatures of carbonate precipitation in relation to plausible temperatures favourable for the establishment of carbon-based life as we know it on Earth (<100-150°C) remain to be established.
www.geos.ed.ac.uk /facilities/ionprobe/mars.html   (980 words)

  
 Mars Astrobiology Magazine
Meteorite ALH84001 believed to have originated on Mars, was found in the Allan Hills region of Antarctica.
Weiss and his colleagues undergraduate student Francis Macdonald, geobiology professor Joseph Kirschvink and collaborators at Vanderbilt and McGill Universities were interested in finding out how much ALH84001 had been heated by the impact that sent it hurtling into space.
ALH84001 and other martian meteorites were once rocks on the Red Planet.
mars.astrobio.net /news/print.php?sid=15   (1657 words)

  
 BBC NEWS | Science/Nature | 'Martian features' found on Earth
In the journal Naturwissenschaften, the authors argue that the globules in ALH84001 may have formed in an alkaline lake on Mars.
One recurrent criticism against the Martian life theory is that nano-bodies in ALH84001 are simply too small to be fossilised life forms.
Professor Vali said the presence of magnetite and iron sulphide in ALH84001 similar to that produced by certain bacteria on Earth was the best sign life once existed on Mars.
news.bbc.co.uk /2/hi/science/nature/3034165.stm   (599 words)

  
 Life on Mars: Meteorites
ALH84001, the Allen Hills meteorite, according to some scientists, has revealed fossil evidence to suggest that bacterial life existed on Mars two billion years ago.
The second possible source crater for ALH84001 is located east of the Hesperia Planitia region, is 11 x 9 km in diameter, and also displays a pristine ejecta blanket and sharp crater rim.
Other rock samples besides ALH 84001 were treated exactly the same as the ALH 84001 samples with the bacteria shapes -the bacteria-shaped features were not seen on the other samples, and were not seen on samples of ALH 84001 without carbonate mineral globules.
www.resa.net /nasa/mars_life_meteor.htm   (5127 words)

  
 Science News Online - This Week - Feature Article - 12/14/96   (Site not responding. Last check: 2007-11-07)
However, closer inspection of the internal structure of the magnetite in ALH84001 revealed that it could not have been formed by a living organism, the team says.
The other elongated crystals in ALH84001, the platelets, which appear to correspond to the ovoid microscopic fossils, don't have this defect but are often associated with the whiskers.
She says the composition of the carbonates varies throughout the tiny samples of ALH84001 the team examined, with bands of calcium-rich carbonates adjacent to calcium-poor ones, for example.
www.sciencenews.org /sn_arch/12_14_96/bob1.htm   (1511 words)

  
 PSR Discoveries: Hot Idea: Evidence for low-temperature formation of carbonates in ALH84001   (Site not responding. Last check: 2007-11-07)
uch of the evidence for fossil life in martian meteorite ALH84001 is contained in globules, plates, and veins of chemically-complex carbonate minerals.
The interpretations stem from measurements of the magnetic properties of minerals in ALH84001 (Kirschvink and others, 1997) and from the chemical and isotopic compositions of carbonates (Valley and others, 1997).
The temperature at which the carbonates in ALH84001 formed is one of the most hotly debated issues about the evidence for fossils in the meteorite.
www.psrd.hawaii.edu /May97/LowTempCarb.html   (1997 words)

  
 Spaceflight Now | Breaking News | New report offers evidence of primitive life on Mars
Scientists generally agree that ALH84001 is a member of the group of 16 meteorites found on Earth that originated on Mars.
The authors found that about a quarter of the Martian magnetites from ALH84001 are identical to magnetites produced on Earth by magnetotactic bacteria strain MV-1, which has been extensively studied by coauthor Bazylinski, a geobiologist and microbiologist who has developed many ways of culturing these difficult to grow microorganisms.
When the team asserted in 1996 that Martian meteorite ALH84001 showed signs of life existing on Mars, that planet was not known to have ever had a strong magnetic field.
spaceflightnow.com /news/n0012/14marslife   (885 words)

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