Why are Most Meteorites Found in Antarctica?

More meteorites have been found in Antarctica than all other continents combined. Why is that?

What is a Meteorite?

Meteorites fall all over the Earth every year. A meteorite is a “space rock” or meteoroid that has traveled through our atmosphere and landed on the surface of the Earth.

The speed and force at which a meteoroid travels through the Earth’s atmosphere resulting in most of the rock burning off. Most meteoroids completely burn up upon entering the Earth’s atmosphere.

Of those that do survive, less than 5% of the original rock remains after impact with the ground. Meteorites on average, can range in size from dust grains to a small rock the size of a human fist.

How Many Meteorites Have Been Found?

To date, more than 69,000 meteorites have been found so far.

Where Have Meteorites Been Found?

Of the 69,268 recorded meteorites in the Meteoritical Bulletin Database, 62.6% of meteorites have been retrieved from Antarctica.

Most meteorites are found in deserts, of which Antarctica is a polar desert. Other regions with high counts of retrieved meteorites are the Sahara Desert of northern Africa (Over 14,000 meteorites) and the the Arabian Peninsula (about 4,200).

Meteorites tend to accumulate in desert areas as conditions tend to preserve the rocks.

Meteorites in the United States

Between 1807 and 2018, 1,884 meteorites have been recorded from the United States. Texas has the most meteorites collected with 313, followed by California (266), and then New Mexico (226). All of these three states have large arid areas.

Why are More Meteorites Recovered in Antarctica?

Antarctica leads the continents in the number of recovered meteorites for several reasons. One reason is not because more meteorites land in Antarctica. Statistically, meteorites can land anywhere on Earth. Most fall into the ocean due to the fact that the world’s oceans cover 70% of the world’s surface.

Meteorites also fall in other locations on Earth. Some have fallen in suburban and urban areas and damaged buildings. Others have left large indentations in the Earth’s surface known as impact craters. Others fall in remote areas of the world and leave no sign of their presence.

Meteorites in Antarctica are more visible because the environmental conditions are favorable for the preservation and retrieval of these space rocks. The arid and cold Antarctic environment helps to preserve these rocks.

The lack of rocks and the contract with ice makes spotting meteorites much easier.

Where are Meteorites Found in Antarctica?

Most meteorites in Antarctica are found on blue ice. Areas of blue ice lack snow cover and allow the meteorites to be more easily exposed.

In addition, researchers have identified meteorite hotspots known as “meteorite stranding zones”. These are areas where the local geology, the flow of the ice, and climate conditions promote the aggregation of meteorites at the surface of the blue ice.

Blue ice areas in Antarctica as seen on a satellite image. Image: NASA.

How Researchers Use Satellites to Find Meteorites

The first recorded meteorite in Antarctica is the Adelie Land meteorite in 1912. In the last few decades, researchers have been actively exploring Antartica to retrieve tens of thousands of meteorites which are used to understand the history of the Solar System. Some meteorites that land in Antarctica are more than a million years old.

Researchers can now use remote sensing and satellite data to map out areas in Antarctica that are most likely to contain meteorites. By searching for areas that meet the environmental and climatic conditions that favor “meteorite stranding zones”, researchers can highlight areas in Antarctica that have a high probability of yielding more meteorites.

Researchers estimate there might be as many as 300,000 more meteorites that remain to be discovered in Antarctica. These researchers estimate that only 15% of meteorites have been recovered so far.

Map showing areas where there is a high probability of finding meteorites in Antarctica based on geological, environmental, and climatic conditions. Map: NASA using data courtesy of Tollenaar, V., et al. (2022).

References

Korotev, R. L. (2021, August). Meteorites in the United States. Washington University in St. Louis. https://sites.wustl.edu/meteoritesite/items/meteorites-in-the-united-states/

Korotev, R. L. (2021). Some meteorite statistics. Washington University in St. Louis. https://sites.wustl.edu/meteoritesite/items/some-meteorite-statistics/

Meteors & meteorites. (2019, December 19). NASA Solar System Exploration. https://solarsystem.nasa.gov/asteroids-comets-and-meteors/meteors-and-meteorites/in-depth/

Tollenaar, V., Zekollari, H., Lhermitte, S., Tax, D. M., Debaille, V., Goderis, S., … & Pattyn, F. (2022). Unexplored Antarctic meteorite collection sites revealed through machine learning. Science Advances8(4), eabj8138. DOI: 10.1126/sciadv.abj8138

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Fonte : National Geographic