Antarctica’s ice certainly seems to be hiding a lot. Just recently, scientists discovered the world’s largest canyon system, twice the size of the Grand Canyon, beneath the surface of East Antarctica. Now, a new experimental study in Nature Communications suggests that a hidden cache of iron meteorites may be found no more than half a meter (1.64 feet) beneath the ice, potentially preserving the recorded history of the formation of our Solar System.
Antarctica is a renowned meteorite collection site, primarily for two reasons. Firstly, meteorites tend to be dark in color, which are easy to spot on the pristine, white icy plains of the southernmost continent. Secondly, ancient meteorites that have long been buried beneath the ice are moved towards the surface by upward-flowing ice; this happens when a glacier suddenly slows down, which squeezes out parts of it. This mechanism concentrates meteorites at the surface, often near mountain ranges, in areas known as “meteorite stranding zones.”
It’s not surprising, then, that about 35,000 meteorite samples, over two-thirds of the world’s total number of collected specimens, have been recovered from Antarctica, which include many lunar and Martian examples. However, as this new study points out, stony meteorites are found far more frequently in Antarctica than iron meteorites.
Meteorite samples of both types should be evenly distributed across Earth, so the reason for this iron deficit has long baffled scientists. In order to solve this mystery, a team of researchers from the University of Manchester set up a novel experiment designed to find out if these iron meteorites might actually be hiding beneath the ice.
The team encased two spherical meteorites, one stony and one iron-rich, in a block of ice within a temperature-controlled chamber, and exposed them to a lamp that simulated natural Antarctic sunlight.
A meteorite just waiting to be snatched up by an intrepid researcher. Antarctic Search for Meteorites Program/Katherine Joy
Although both samples were able to heat up enough to melt the surrounding ice to a degree, the iron meteorite sank 1.6 times faster than the stony meteorite. The metallic composition of the iron meteorite meant that it was able to conduct heat more efficiently, allowing it to melt through more ice.
In order to confirm their findings, the researchers applied this model of meteorite heating to Antarctica’s Frontier Mountain, a well-known meteorite trap. Their computer simulations calculated that the stony meteorites will almost always appear at the surface, whereas iron variants are likely to remain trapped below the ice. The implication of this finding is that there’s a layer of iron meteorites hiding just underneath the icy surface of Antarctica.
“Every one of these iron meteorites could potentially represent the interior structure of a protoplanet that never made it to full-size,” Dr. Katherine Joy told IFLScience. “This means that, by finding them, we can access the cores of planetary bodies that don’t exist anymore.”
Every single one found, therefore, provides an insight into the creation, evolution, and destruction of some of our Solar System's youngest rocky objects – failed planets or giant asteroids that ultimately broke apart.