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NSF Fact Sheet

 

Media contact:

 Peter West

 (703) 292-8070

 pwest@nsf.gov

The Search for Antarctic Meteorites

Researchers scour Tentacle Ridge in Antarctica's Darwin Glacier region; caption is below
Researchers for the National Science Foundation's Antarctic Search for Meteorites (ANSMET) program scour Tentacle Ridge in Antarctica's Darwin Glacier region for specimens with the help of volunteers from Raytheon Polar Services Company.
Photo courtesy of ANSMET/Case Western Reserve University
Select image for larger version
(Size: 85KB)
 

Meteorite ALH84001; caption is below
Meteorite ALH84001, which was found in the Allan Hills of Antarctica by NSF's Antarctic Search for Meteorites Program.
Photo Credit: NSF
 

Meteorite ALH84001; caption is below
Meteorite ALH84001, which was found in the Allan Hills of Antarctica by NSF's Antarctic Search for Meteorites Program.
Photo Credit: NSF

Background

The National Science Foundation (NSF), through its Office of Polar Programs (OPP), is the lead agency of a consortium of U.S. government agencies that searches for, characterizes, and makes available to researchers worldwide, meteorites that have landed in Antarctica. NSF, through the U.S. Antarctic Program, coordinates almost all U.S. scientific research in the Antarctic. NSF is an independent federal agency and is the only federal agency whose mission covers research in all fields of science and engineering.

Organization

The Antarctic meteorite program is a collaborative effort of NSF, NASA, and the Smithsonian Institution. NSF, through the Antarctic Search for Meteorites (ANSMET) Program, supports the collection of meteorites in Antarctica. ANSMET is presently supported by a grant to Case Western Reserve University in Cleveland, Ohio. NASA and the Smithsonian Institution provide for the classification, curation, and distribution of Antarctic meteorites. All three agencies sponsor research on these specimens.

ANSMET's goals

ANSMET's primary goal is to recover an unbiased and uncontaminated sample of meteorites each year. The program aims to recover a sufficiently large number of meteorites each Antarctic research season to make it likely that a few unusual or unique specimens will be collected.

Since 1976, ANSMET has recovered more than 10,000 specimens from meteorite stranding surfaces in the Transantarctic mountains. These specimens serve as one of the most reliable, continuous sources of new, non-microscopic extraterrestrial material. The study of Antarctic meteorites has greatly extended knowledge of the materials and conditions in the primeval nebula from which our solar system was born; revealed the complex and exotic geologic nature of asteroids; and proved that some specimens recovered from Antarctica represent planetary materials from the Moon and Mars.

Why Antarctica?

Antarctica is one of the best places on Earth to search for meteorites for two reasons:

  • Although meteorites fall randomly all over the globe, it is much easier to find a meteorite if the background material it is resting on is light colored and plain, and there are few terrestrial rocks to complicate the search. Both of these factors make the East Antarctic ice sheet an excellent place for finding meteorites.

  • Along the margins of the ice sheet, ice flow is sometimes blocked by mountains and other obstructions, exposing slow moving or stagnant ice to the fierce "katabatic" winds that roar down the ice cap from the South Pole to the ocean. These winds, in turn, scour away the ice, leaving behind a deposit of meteorites representing those that were sprinkled throughout the volume of ice lost to the wind. When such a process continues for tens or hundreds of thousands of years, as is the case in Antarctica, the concentration of meteorites can be spectacular. There are indications that some of the surfaces where meteorites have been found may have been active for millions of years

Finding meteorites

Meteorite collection follows a system developed over the past 25 years that allows for the most efficient search over a wide area with the minimum of logistical support.

Six-person recovery teams leave from McMurdo Station, the main U.S. research station in Antarctica, for remote field sites for a period of 5-7 weeks. The teams are self-sufficient in terms of equipment, fuel, food, and other materials, and are housed in tents. They generally are flown into the field aboard ski- equipped aircraft, such as Twin Otters or LC-130’s. From the landing site, the field team moves to a meteorite-stranding surface, where systematic searching begins. To search, the field team, on snowmobiles, forms a line roughly 30 meters (100 feet) apart and slowly drives across the icefield, scanning for specimens. The transects are arranged to provide significant overlap making it less likely that specimens will be missed and minimizing exposure to uncomfortable crosswinds which affect visibility.

Many meteorite-stranding surfaces require several years to search because of their size. Training helps ensure consistent recovery methods from year to year. This, in turn, ensures that the sum of collected meteorites from a given icefield constitute an unbiased sample of the meteorites.

Once a sample is located, it is assigned an identification number; its position is established using the Global Positioning System (GPS) and notes are made of its size, possible classification, and any distinguishing features such as shape or color. The sample is then collected in a sterile Teflon bag, with care being taken to avoid contact with any mechanical or biological materials. While the field season is in progress, these samples are carefully inventoried and kept frozen.

When the team returns to McMurdo, the meteorites are transferred to special shipping containers and sent, still frozen, to the Antarctic Meteorite Curation Facility at NASA's Johnson Space Center (JSC) in Houston, Texas. There the meteorites are carefully removed from their sealed bags, dried to remove any attached snow or ice, and stored under cleanroom conditions.

How are meteorites distributed for research use

After each new specimen arrives at JSC, and has been freeze-dried to remove any ice or snow, technicians there carefully examine the meteorite both macro- and microscopically. Small chips are then broken off for initial classification, by curatorial staff at both JSC and at the Smithsonian Institution.

The product of these initial examinations is a short written description, which is subsequently published in the Antarctic Meteorite Newsletter that is distributed to researchers and facilities around the globe twice each year. This newsletter invites interested researchers to request samples by submitting requests to the Curator of Meteorites at JSC. Sample requests that fall outside of established curatorial policies for distribution are considered by the Meteorite Working Group, an expert peer group established to provide technical advice about sample handling and allocation.

For more information about the ANSMET Program, see: http://www.cwru.edu/affil/ansmet/

For NASA's Johnson Space Center's meteorite program, see: http://wwwcurator.jsc.nasa.gov/curator/antmet/program.htm

For NSF's most recent news release on ALH84001, an Antarctic meteorite of Martian origin, see: http://www.nsf.gov/od/lpa/news/press/00/pr0096.htm

Broadcasters

B-roll and sound bites from NSF’s Scott Borg are available on Betacam SP, contact NSF’s Dena Headlee, (703) 292-8070/dheadlee@nsf.gov

 

 
 
     
 

 
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