Some of the great secrets of our solar system are perhaps best unraveled by looking down rather than up.

It is 1969 and the first humans set foot on the moon. It is an event that is still etched on many people’s retinas and that immediately comes to the fore in later generations when the year 1969 is mentioned. But what few know is that 1969 is also the year when Antarctic scientists encounter the first meteorites in so-called blue ice regions, discovering a previously unknown concentration mechanism that ensures that significant numbers of meteorites are up for grabs in specific parts of Antarctica. . In the years that followed, more than 45,000 meteorites were discovered in Antarctica thanks to that new insight.

A new map

And that’s just the beginning this is what researchers now say in the sheet Science Advances. “According to our calculations, there would be more than 300,000 meteorites still present on the surface of the ice sheet, with enormous scientific potential,” said researcher Steven Goderis. The estimate is based on a brand new “treasure map” that reveals across the continent where those meteorites are most likely to be and could make future searches a lot easier.

A lot of meteorites

The fact that so many meteorites have already been found in Antarctica to date and that many more meteorites are waiting to be discovered can easily be explained, explains researcher Veronica Tollenaar. “There are actually three reasons for this. First of all, you can easily see meteorites on ice, because meteorites are dark and the ice is light blue. In addition, Antarctica has very cold conditions, which means that the meteorites can be well preserved and have little or no weathering. The main reason, however, is the concentration mechanism, which was discovered in 1969 and ensures that the meteorites that fall on Antarctica are brought together in a relatively small area by ice currents.” When meteorites fall on Antarctica, they are quickly covered by a layer of snow that – under the influence of new snow layers – is compressed and forms a new ice layer. The meteorite gets stuck in that ice layer and flows together with the ice – under the influence of gravity – towards the coast. Some of the ice will reach the coastal waters without too many problems and melt there, so that the meteorite eventually ends up at the bottom of the sea. “But some ice flows encounter barriers: mountains that cause older ice sheets – containing the meteorites – to be propelled to the surface. And in the places where that happens, meteorological processes often also take place that ensure that the old ice sublimates, so that the meteorites really come to lie ‘loose’ on the surface.” Such areas are – because of their blue color, caused by all air bubbles squeezed out and replaced by large ice crystals that absorb blue light poorly – also called blue ice areas.

A schematic representation of the concentration mechanism that ensures that many meteorites can be found in certain places in Antarctica.

the treasure map

Since researchers have learned of the existence of this concentration mechanism, some of these blue ice regions have been targeted – but with varying degrees of success – for meteorites. Reason enough for Tollenaar and colleagues to take a closer look at the areas and to make a new and accurate forecast for all blue ice areas in Antarctica where meteorites can be found. To this end, data was used from places where many meteorites have already been found. “We threw that into a machine-learning algorithm,” says Tollenaar. The algorithm thus became familiar with the properties that can be attributed to an area rich in meteorites. Then the algorithm was presented with relevant properties of other areas: “We found that the speed of the ice flow, the temperature, data indicating whether there is snow or ice on the surface and the slope of the surface together predict whether meteorites can be found somewhere. .” And based on that data – and experience with meteorite-rich areas – the algorithm was then able to identify more than 100,000 places where meteorites are expected to be found. “That’s actually 100,000 pixels measuring 450 by 450 meters, which we clustered into over 600 areas that vary in size from a few square kilometers to hundreds of square kilometers,” says Tollenaar.

Reliability

But how reliable is that algorithm now? The researchers have also considered this question and based on independent data – which were not used to train the algorithm – they estimate that the algorithm is correct in more than 80 percent of the cases. “We then estimated with the uncertainties of our forecasts and the fact that 5 meteorites per pixel have been found in previous meteorite missions that there are at least 300,000 – but perhaps many more – meteorites in Antarctic blue ice areas waiting to be discovered.”

game changer

The resulting card can be a game changer to turn out. “We now have a map for the entire continent, based on very systematic research. There was no such thing.” And on that map, researchers have been able to highlight some really interesting areas. “We found several never-visited meteorite-rich areas that are relatively close to research stations,” says Tollenaar. But also in other areas that researchers may have already had on the radar, thanks to the map, searches can now be more targeted. And that also increases the chance of success, which makes the very expensive meteorite missions a lot more attractive. “We are at the dawn of a new era for Antarctic meteorite missions,” Tollenaar predicts. Not only thanks to the new treasure map, but also thanks to all kinds of other developments. “For example, we now want to use new detection techniques in the field, such as drones.”

In red the meteorite-rich areas. The research stations are also indicated on this map.

We should therefore not be surprised if scientists bring home one meteorite after another from Antarctica in the coming decades and in this way gradually gain more insight into the rich history of our solar system. “Meteorites contain crucial information about the origin and development of our solar system and can help answer questions such as ‘where do we come from?’ and ‘how did life originate’? They are therefore very important for fundamental research,” says Tollenaar, who, to her regret, has never been on a meteorite mission to Antarctica, but now has the prospect of such an adventure. “We are currently making initial preparations for a meteorite mission that should take place next year,” she said. “And the Université libre de Bruxelles, which I am affiliated with as a PhD student, regularly undertakes such missions, so I think it is very likely that it will happen in the future. And when the time comes, I can take my own treasure map with me!”