The isolated southern expanse of the Earth is an alien realm, with vast expanses of white ice and blue sky that appear to stretch on infinitely.

 

Despite its barren landscape, the Antarctic continent holds secrets to the origins of our Earth and the solar system in the form of meteorites. Meteorites are solid pieces of debris that originate in outer space, survive the journey through our atmosphere, and fall to the Earth’s surface.(1) Their unique components and pungent smells contain fascinating stories of cosmic clouds, condensing stardust and the fiery collisions of entire planets.

 

These ‘space rocks’ can land anywhere on Earth, but the vast majority of meteorites are found in the cold deserts of Antarctica.(2) So, why Antarctica?

 

Across the globe, meteorite abundance is dependent on two factors: the meteorites must be easy to spot, and their preservation must be guaranteed over long time periods.(3)

 

It is the conditions of the Antarctic landscape that make all the difference when it comes to meteorite discovery. The cold, dry nature of Antarctica helps to preserve these extraterrestrial rocks, allowing for more pristine samples to be collected. In this way, we may think of Antarctica as a ‘natural freezer’. In fact, meteorites can be buried and preserved in the Antarctic ice for up to millions of years, allowing for a deep dive into the origins of the solar system upon analysis. Furthermore, meteorites are easier to find in Antarctica due to the stark contrast between the dark colours of meteorites and the white ice. And since so few rocks naturally form on ice sheets, you can be fairly certain the majority of rocks found in Antarctica are extraterrestrial.

 

However, an expedition to Antarctica for meteorite hunting is no small feat. Thankfully, landscape processes occurring on the Antarctic continent create concentrated pockets of meteorites, making the hunt for meteorites less like trying to find a needle in a haystack.

 

These meteorite hotspots are largely a result of the local geology and movement of ice across the Antarctic landscape.(4) As meteorites strike glaciers, they are buried and encased in the ice. These glaciers move across the landscape, acting as ‘conveyor belts’ that carry the meteorites until they reach a large barrier, such as the Transantarctic Mountains. The ice flow is blocked and builds up at the base of the mountain. Here, dry Antarctic winds slowly erode the ice, revealing a bounty of imprisoned meteorites. 

 

Traditionally, meteorites have been divided into three broad categories: stony, stony-iron, and iron.(5) While stony meteorites are made up of silicate minerals, iron meteorites are almost completely made of metal. Unsurprisingly, stony-iron meteorites are composed of nearly equal amounts of metal and silicate crystals.

 

Alarmingly, warmer temperatures and melting ice associated with global warming may hinder our search for meteorites. This is particularly the case for iron meteorites, which conduct heat more efficiently than other meteorite types due to their higher metal content.(6) Consequently, meteorites can sink into the ice and out of sight.

 

Despite Antarctica’s otherworldliness, it is not free of the impacts brought about by human activity occurring on landmasses separated by vast seas.

 

However, with the help of artificial intelligence and machine-learning, the quest for meteorite discovery continues. Scientists recently estimated there are as many as 300,000 more meteorites to be discovered in Antarctica, their stories waiting to be uncovered in a never-ending game of hide-and-seek.(7)

 

Using machine learning to combine satellite measurements of temperature, surface slope, speed of ice flow, and reflection of radar signals by ice, scientists have developed a ‘treasure map’ containing the predicted locations of concentrated meteorite zones.(7)

 

The ’treasure map’ is accessible online,(8) so anyone can search the Antarctic continent for rocky remnants left over from the formation of the solar system.

 

When we think of space exploration, we conjure up images of astronauts and spaceships. But Antarctica provides us with the opportunity to peer into the cosmos without ever leaving Earth, given we are brave enough to face the inhospitable conditions and pervasive alienness of the Earth’s southernmost continent.

 

 

References

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1.     Sephton M, Bland P, Pillinger C, Gilmour I. The preservation state of organic matter in meteorites from Antarctica. Meteoritics & Planetary Science. 2004;39(5):747-54.

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2.     Corrigan C. Antarctica: The Best Place on Earth to Collect Meteorites. CosmoELEMENTS; 2011. p. 296.

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3.     Schlüter J, Schultz L, Thiedig F, Al‐Mahdi B, Aghreb AA. The Dar al Gani meteorite field (Libyan Sahara): Geological setting, pairing of meteorites, and recovery density. Meteoritics & Planetary Science. 2002;37(8):1079-93.

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4.     Steigerwald B. NASA Scientist Collects Bits of the Solar System from an Antarctic Glacier Greenbelt: NASA; 2018 [Available from: https://www.nasa.gov/feature/goddard/2018/antarctic-meteorites.

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5.     Lotzof K. Types of meteorites [Internet]. Natural History Museum;  [Available from: https://www.nhm.ac.uk/discover/types-of-meteorites.html.

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6.     Evatt G, Coughlan M, Joy K, Smedley A, Connolly P, Abrahams I. A potential hidden layer of meteorites below the ice surface of Antarctica. Nature communications. 2016;7(1):1-8.

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7.     Tollenaar V, Zekollari H, Lhermitte S, Tax DM, Debaille V, Goderis S, et al. Unexplored Antarctic meteorite collection sites revealed through machine learning. Science Advances. 2022;8(4).

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8.     Tollenaar V, Zekollari H, Lhermitte S, Tax DM, Debaille V, S G. Antarctic Meteorite Stranding Zones [Internet].  [Available from: https://wheretocatchafallingstar.science/.