(ORDO NEWS) — A Belgian-Dutch team of scientists has created the first-ever “treasure map” that shows where meteorites can be found in Antarctica. Meteorites are chunks of rock-like material that can be found on the Earth’s surface after falling from space.
Unlike terrestrial rocks, meteorites were spared the weathering and volcanism on our planet and are therefore considered an invaluable archive of the earliest stages in the development of our solar system.
While rocks can’t tell us anything about the first half billion years of our planet’s 4.55 billion years, most meteorites from the asteroid belt take us back 4.6 billion years. The overwhelming majority of meteorites registered in Antarctica come from the asteroid belt, about 1% – from the Moon and Mars.
Meteorites regularly fall on the Earth’s surface: about 50 meteorites weighing more than 10 g fall annually in France. However, searching for them is like searching for a needle in a haystack, and scientists from meteorite campaigns often return empty-handed.
In contrast, finding meteorites at the distant South Pole is surprisingly easy. This is due to a principle known as the concentration mechanism, where specific ice flows and meteorological conditions cause meteorites to accumulate in rather small areas known as meteorite accumulation zones.
When meteorites hit Antarctica, they tend to get stuck in the ice sheet and drift towards the oceans. This has led some to call ice the “natural conveyor belt” for meteorites. Sometimes they encounter mountains in their path, sometimes hidden under the ice sheet, and redirect them to the surface of the ice sheet.
Meteorites are always found on the surface where the wind blows snow away, leaving exposed ice with a blue tint. Such zones are known as blue ice zones. Although meteorites are always recorded in such zones, not all of them contain them.
Once a blue ice zone rich in meteorites has been discovered, it is quite easy to spot dark-colored rocks against a background of light-colored ice.
The success of the search for meteorites in Antarctica is unparalleled: more than 60% of meteorites found on Earth are found in the ice sheet of Antarctica. However, the potential remains largely untapped: to date, only a fraction of all blue ice patches in Antarctica have been tested for the presence of meteorites, with varying degrees of success.
To determine where to look for meteorites, it is necessary to understand what distinguishes a meteorite-rich zone of blue ice from a zone without meteorites.
There is a lot of data for this: the location and year of discovery of meteorites are stored in a special database of meteorite bulletins. Scientists can also access field reports detailing some of the successful and unsuccessful meteor missions that have taken place since the discovery of the concentration mechanism in 1969.
Until now, the decision on where to look has been made by a small number of experts. This means that a huge human factor is involved in meteorite search missions, and it is impossible to assess the potential of each individual area on a continent that is about 25 times the size of France.
To help plan the often costly and logistically challenging missions, our team has developed a map that shows potential meteorite impact areas.
In order to make a “treasure map” of meteorites, we had to translate the real world into observable numbers. To do this, we applied a grid of cells 450×450 meters in size to the blue ice zones and their immediate surroundings.
Where meteorites have been found within a grid cell, the cell is marked as “positive”. The rest of the grid cells remain unmarked. Each cell contains information derived from satellite and radar observations, including surface temperature, ice flow velocity, land cover types, or slope. Such data allows us to predict where we might find meteorites.
Machine learning and statistical models allow us to combine these different observations and take into account possible uncertainties associated with the data.
The operation of the prediction algorithm is optimized by several iterations. Each time, the predictions of the algorithm are checked in several areas, which are known to have meteorites or not.
The operation of the algorithm can be divided into several stages. First, the algorithm learns what a typical positive or unlabeled grid cell is. By examining data related to different grid cells, the algorithm can calculate the probability that an unlabeled grid cell contains meteorites or not.
Then the cells of the grid potentially containing meteorites are grouped into zones of meteorite piles, the area of which varies from several to hundreds of square kilometers. Our studies have shown that the accuracy of forecasting meteorite fall zones is more than 80%.
The analysis of the predicted zones confirms that the machine learning algorithm was able to capture the interaction between various phenomena. While opportunities to search for meteorites exist across the continent, some areas near existing research stations remain unexplored, making a visit to explore very attractive.
This “treasure map” heralds a new era for finding meteorites in Antarctica. By sharing our research with colleagues around the world, we approach meteorite collection as a community effort. In response, scientists from countries as diverse as Korea, India, Chile, and the United States expressed interest in exploring these areas.
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