ANSMET

ANSMET

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ANSMET is a program funded by the Office of Polar Programs of the National Science Foundation
National Science Foundation
The National Science Foundation is a United States government agency that supports fundamental research and education in all the non-medical fields of science and engineering. Its medical counterpart is the National Institutes of Health...

 that looks for meteorites in the Transantarctic Mountains
Transantarctic Mountains
The three largest mountain ranges on the Antarctic continent are the Transantarctic Mountains , the West Antarctica Ranges, and the East Antarctica Ranges. The Transantarctic Mountains compose a mountain range in Antarctica which extend, with some interruptions, across the continent from Cape Adare...

. This geographical area serves as a collection point for meteorites that have originally fallen on the extensive high-altitude ice fields throughout Antarctica. Such meteorites are quickly covered by subsequent snowfall and begin a centuries-long journey traveling "downhill" across the Antarctic continent while embedded in a vast sheet of flowing ice. Portions of such flowing ice can be halted by natural barriers such as the Transantarctic Mountains. Subsequent wind erosion of the motionless ice brings trapped meteorites back to the surface once more where they may be collected. This process concentrates meteorites in a few specific areas to much higher concentrations than they are normally found everywhere else. The contrast of the dark meteorites against the white snow, and lack of terrestrial rocks on the ice, makes such meteorites relatively easy to find. However, the vast majority of such ice-embedded meteorites eventually slide undiscovered into the ocean.

Importance


The ANSMET program, together with parallel Antarctic collection programs run by Japan, China, and other nations, is a major source of the extraterrestrial material that is available for scientific investigation. All of the material collected by ANSMET is curated for the purpose of research and public education, in contrast to meteorites collected privately, the bulk of which are frequently sold to collectors.

While the vast majority (>90%) of the meteorites found are ordinary chondrites
Ordinary chondrite
The Ordinary chondrites are a class of stony chondritic meteorites. They are by far the most numerous group and comprise about 87% of all finds...

, ANSMET has provided many rare meteorites, including many of the known lunar
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 and martian
Mars
Mars is the fourth planet from the Sun in the Solar System. The planet is named after the Roman god of war, Mars. It is often described as the "Red Planet", as the iron oxide prevalent on its surface gives it a reddish appearance...

 meteorites such as ALH84001
ALH84001
Allan Hills 84001 is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984 by a team of U.S. meteorite hunters from the ANSMET project. Like other members of the group of SNCs , ALH 84001 is thought to be from Mars. However, it does not fit into any of the previously...

.

Method


The search for the meteorites is done visually. A team of four to ten explorers, typically meteorite scientists, lives for 5–7 weeks on the ice field. Using snowmobiles spaced 30 m apart they scan the blue ice for meteorites. Once a specimen has been located its position is found using GPS and it is given an identification number. It is then placed in a sterile Teflon bag. The teams make sure that the specimen remains frozen throughout its journey back to the Antarctic Meteorite Curation Facility at the Johnson Space Center in Houston
Houston, Texas
Houston is the fourth-largest city in the United States, and the largest city in the state of Texas. According to the 2010 U.S. Census, the city had a population of 2.1 million people within an area of . Houston is the seat of Harris County and the economic center of , which is the ...

, Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...

. Since 1976, ANSMET has returned over 17,000 meteorites. Meteorites of greater interest and undergoing detailed study are kept at JSC for distribution to the scientific community, though, ultimately, all samples collected by ANSMET are transferred to the Smithsonian Institution
Smithsonian Institution
The Smithsonian Institution is an educational and research institute and associated museum complex, administered and funded by the government of the United States and by funds from its endowment, contributions, and profits from its retail operations, concessions, licensing activities, and magazines...

 for permanent storage and curation.

The naming convention for antarctic meteorites collected by ANSMET is as follows: a three letter prefix based on the location the meteorite is found, followed by two numbers that designate the year of collection, and a three number unique identifier. For example, ALH84001
ALH84001
Allan Hills 84001 is a meteorite that was found in Allan Hills, Antarctica on December 27, 1984 by a team of U.S. meteorite hunters from the ANSMET project. Like other members of the group of SNCs , ALH 84001 is thought to be from Mars. However, it does not fit into any of the previously...

 was collected in the Allen Hills region in 1984.

The 2004-2005 ANSMET expedition consisted of 12 members and collectively they returned 1,230 meteorites. These included over 130 kg of pallasite
Pallasite
A pallasite is a type of stony–iron meteorite.-Structure and composition:It consists of cm-sized olivine crystals of peridot quality in an iron-nickel matrix. Coarser metal areas develop Widmanstätten patterns upon etching...

 meteorites, one of which is the largest yet found in Antarctica at over 30 kg.

The 2006-2007 ANSMET expedition consisted of a 9 member systematic team (including astronaut Don Pettit) that explored the Grosvenor Mountains
Grosvenor Mountains
Grosvenor Mountains is a group of widely scattered mountains and nunataks rising above the polar plateau east of the head of Mill Glacier, extending from Mount Pratt in the north to the Mount Raymond area in the south, and from Otway Massif in the northwest to Larkman Nunatak in the SE. Discovered...

 and a 4 member reconnaissance team that explored Scott Glacier
Scott Glacier
Scott Glacier is a glacier, wide and over long, flowing northnorthwest to the Antarctic coast between Denman Glacier and Mill Island. It was discovered by the Western Base Party of the Australasian Antarctic Expedition under Mawson and named for Capt. Robert F. Scott....

 and Reedy Glacier
Reedy Glacier
The Reedy Glacier is a major glacier in Antarctica, over 160 km long and from 10 to 19 km wide, descending from the polar plateau to the Ross Ice Shelf between the Michigan Plateau and Wisconsin Range, and marking the limits of the Queen Maud Mountains on the west and the Horlick...

as possible destinations for future expeditions.

The 2009-2010 ANSMET expedition consisted of 8 members that returned 1010 meteorites.

The 2010-2011 ANSMET expedition consisted of a 9 member systematic team and a 4 member reconnaissance team that explored new areas where future teams may go. Collectively they returned over 1200 meteorites.

Further reading


William A. Cassidy, Meteorites, Ice and Antarctica, Cambridge University Press (2003), ISBN 0521258723

External links