Allan Hills 84001

Allan Hills 84001
Meteorite fragment ALH84001
Type	Achondrite
Clan	Martian meteorite
Grouplet	Orthopyroxenite
Composition	Low-Ca Orthopyroxene, Chromite, Maskelynite, Fe-rich carbonate[1]
Shock stage	B
Weathering grade	A/B
Country	Antarctica
Region	Allan Hills, Far Western Icefield
Coordinates	76°55′13″S 156°46′25″E / 76.92028°S 156.77361°E / -76.92028; 156.77361[1]
Observed fall	No
Found date	1984
TKW	1930.9 g
Related media on Wikimedia Commons

Allan Hills 84001 (ALH84001^[1]) is a fragment of a Martian meteorite that was found in the Allan Hills in Antarctica on December 27, 1984, by a team of American meteorite hunters from the ANSMET project. Like other members of the shergottite–nakhlite–chassignite (SNC) group of meteorites, ALH84001 is thought to have originated on Mars. However, it does not fit into any of the previously discovered SNC groups. Its mass upon discovery was 1.93 kilograms (4.3 lb).

In 1996, a group of scientists found features in the likeness of microscopic fossils of bacteria in the meteorite, suggesting that these organisms also originated on Mars. The claims immediately made headlines worldwide, culminating in U.S. president Bill Clinton giving a speech about the potential discovery.^[2] These claims were controversial from the beginning, and the wider scientific community ultimately rejected the hypothesis once all the unusual features in the meteorite had been explained without requiring life to be present. Despite there being no convincing evidence of Martian life, the initial paper and the enormous scientific and public attention caused by it are considered turning points in the history of the developing science of astrobiology.^[3]