ALH84001

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Image:ALH84001.jpg

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. On discovery, its weight was 1.93 kg.

1 History
2 Possible lifeforms
3 Origin on Mars
4 See also
5 References
6 External links

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History

It is one of the oldest known pieces of the solar system, having crystallized from molten rock 4.5 billion years ago. It was shocked and broken by one or more meteorite impacts on the surface of Mars some 3.6 billion years ago, but remained on the planet. It was later blasted off from the surface in a separate impact about 15 million years ago. Following some interplanetary travel, impacted Earth roughly 13,000 years ago. These dates were established by a variety of radiometric dating techniques, including samarium-neodymium (Sm-Nd), rubidium-strontium (Rb-Sr), potassium-argon (K-Ar), and carbon-14.Template:Ref Template:Ref

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Possible lifeforms

In 1996 ALH 84001 became newsworthy when it was announced that it was believed that the meteorite contained traces of life from Mars, as published in an article in Science by Dr. David McKay of NASA Template:Ref. Image:ALH84001 structures.jpg

Under the scanning electron microscope structures were revealed that for some time were considered to be the remains - in the form of fossils - of bacteria-like lifeforms. The structures found on ALH84001 are 20-100 nanometres in diameters, similar in size to the hypothetical nanobacteria, but smaller than any non-hypothetical earthly lifeform. If the structures are really fossilized lifeforms, they would be the first proof of the existence of extraterrestrial life.

This caused a considerable stir at the time and opened up interest in Martian exploration. When the discovery was announced, many immediately conjectured that the fossils were the first true evidence of extraterrestrial life—making headlines around the world, and even prompting U.S. President Bill Clinton to make a formal televised announcement to mark the event.

As of 2005 however, most experts agree that the microfossils are not indicative of life, but of contamination by earthly biofilms. It has not yet conclusively been shown how they formed.

Recent studies on ALH84001 have shown that, although chances are low, eventually, Martian rocks such as ALH84001 could actually transfer Martian life to earth. 1 in 10 million meteorites from Mars arrives in less than a year, and around 10 rocks that weigh more than 100 grams make the journey in 2-3 years. Bacterial spores, and rock dwelling organisms can survive in space for 5 years, meaning transfer of Martian life to our planet is entirely possible.

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Origin on Mars

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. According to the analysis, Eos Chasma in the Valles Marineris canyon appears to be the source of the meteorite Template:Ref. The analysis was not conclusive, in part because it was limited to parts of Mars not obscured by dust.

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