Antarctica hides a cosmic treasure, 430,000 years ago there was a giant explosion

The cosmic rocks that explode upon entering the Earth’s atmosphere are called bolides and are relatively common. From 1988 until release current studies about the current Antarctic find, the US National Aeronautics and Space Administration (NASA) has recorded 861 of them. Superbolides – such as the Chelyabinsk meteorite in 2013 or the Kamchatka meteorite in 2018 – occur less frequently, only a few times in a hundred years.

Air explosions, which would be stronger than the Tunguska event, are even rarer, but even so, scientists assume that they occur more often than the impacts of cosmic bodies capable of creating an impact crater.

It’s hard to find, it’s probably not common

According to a team led by chemist Matthias van Ginneken of the University of Kent specializing in chemical space processes, such an estimate is reasonable.

“If such an event took place over a densely populated area, it could result in millions of casualties and serious damage up to hundreds of kilometers,” van Ginneken said, according to the website. Science Alert One of the reasons why scientists believe that these “space visits” are not very common.

On the other hand, a more accurate estimate is mispronounced, because if such an above-ground explosion has occurred in the past, it is not easy to find recognizable traces of it and correctly identify them. Such a task is much more difficult than recognizing an ancient impact crater, and it is not easy at all. Therefore, our idea of ​​how often such explosions could have been over the ages is only very approximate.

Seventeen small pallasites

A new stimulus evoking this event has now been discovered by scientists in Antarctica. At the top of Walnumfjellet in the Sør Rondane Mountains in Queen Maud’s Land, seventeen tiny particles, no larger than half a millimeter, were found that at first glance looked like ordinary grains of dirt, but something else came up close.

When van Ginneken and his team examined these tiny fragments with a scanning electron microscope, he discovered that they were in fact condensation residues of the bolide.

The team’s study revealed that the ball bodies were chemically predominantly made of iron and olivine with a high nickel content – which corresponded exactly to the composition of a rare stone-iron meteorite known as pallasite, and was a serious indication that the grains found came from space.

It also had a low content of oxygen-18, the heaviest natural isotope of oxygen, which occurs in lower concentrations in cold environments such as polar ice. In this respect, they have been shown to be surprisingly similar to other condensation “fossilized droplets” previously found in other areas of Antarctica, the origin of which was dated by 480,000 to 430,000 years ago.

According to van Ginneken, this similar chemical profile suggests that all the “spheres” were created by the same meteorite event that occurred about 430,000 years ago.

A stronger air explosion than humanity knows

The chemical composition also told scientists more about what the explosion itself looked like. According to scientists, a simple explosion of a meteorite, which will still occur in the atmosphere, leave a solid trace in the form of condensation spheres on Earth, is relatively rare – these grains are usually found only in connection with the impact of such a large space body to leave a crater.

However, the team did not find any impact crater. In addition, the condensation grains were scattered over a wide area. Both of these clues pointed to one thing: the explosion that created them must have occurred in the air – and it must have been much stronger than those with which humanity was personally acquainted.

The course of the meteorite explosion in the atmosphere is one of the phenomena that has not yet been sufficiently investigated. However, scientists believe that this is due to the high pressure of the air, which acts on the falling meteorite and enters the cracks that appear in it – this increases the internal pressure, until eventually the entire cosmic rock disintegrates.

The heat generated in connection with this process will then probably evaporate the material in the meteorite, which will “burst” above the ground as a result of the explosion. In a colder environment, the evaporated material condenses again and, in the case of Antarctic bodies, mixes with the ice sheet – thanks to which a small proportion of oxygen-18 has been found in them.

Armageddon can take many forms

According to van Ginneken’s team, the Antarctic event must have been stronger than the 1908 Tunguska meteorite explosion, which could have been estimated to be three to 10 megatons of TNT (by comparison, the power of an atomic bomb launched over Hiroshima was about 15,000 tons).

At the same time, the one hundred and thirteen-year-old meteorite explosion demonstrably leveled 2,150 square kilometers of forest and cut down an estimated 80 million trees. If the Antarctic event was really even stronger, according to van Ginneken, science should pay more attention to superbolides.

“To get an overview of the impact of asteroids on Earth as fully as possible, other studies examining rocks or the ocean floor, for example, should focus on identifying similar events, as the Antarctic ice sheet covers only nine percent of the earth’s surface,” van Ginneken said.

“Our research can help identify these events, for example, in the core of deep well sediments,” he added. However, the question is how optimistic such research (revealing that a possible doomsday can occur for the Earth more often than we thought over the ages).

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