The cause of the Tunguska event of 1908 remains a mystery today, even though one of the prevailing theories -- that a meteorite had scored the Earth and displaced thousands of trees in Siberia near the Podkamennaya Tunguska River and created a crater that became Lake Cheko -- has now been debunked, because theories, by their very construct, can be tested and sometimes found wanting. The Tunguska event's cause is still a mystery, though, because that particular question remains unanswered. But one thing it was not caused by, Russian scientists are now claiming, was a meteor with a meteorite impactor.
Sputnik International reported this week that Russian scientists from Krasnoyarsk and Novosibirsk visited in 2016 the area believed to be, according to one theory, an impact crater for the Tunguska event meteorite -- Lake Cheko. The lake, according to some, had not existed prior to 1908, but the scientists were working on the supposition that, given that the area had been poorly mapped prior to the 20th century, accounts could be wrong concerning the age of the lake. In short, it might have existed prior to the Tunguska event itself.
So the team took core samples of the bottom sediments of Lake Cheko with which to get a more accurate assessment of just how old the lake at the middle of the Tunguska event mystery might be. This would be done through geochemical and biochemical analyses.
They took the core samples, which were pulled from the deepest trench in Lake Cheko, to the Institute of Geology and Mineralogy, Siberian Branch of The Russian Academy of Sciences (RAS). The RAS conducted a radioscopic analysis of the samples and found that, despite the commonly held belief that Lake Cheko was barely over a century old, it was almost three times as old.
From the press release at The Russian Geographical Society:
"The study showed that the deepest sample is about 280 years old, which means that the lake is probably even older, because the researchers did not manage to obtain samples from the very bottom. Nevertheless, this proves that Lake Cheko is much older than the Tunguska event and is not an impact crater of a supposed Tunguska meteorite impact."
One eyewitness by the name of Vanara was knocked from his chair at a trading post 40 miles from the estimated epicenter of the blast, according to a 2008 event article at the NASA website. Moments later he felt as if his shirt was on fire. In fact, he said the sky looked as if it were on fire.
"Suddenly in the north sky… the sky was split in two, and high above the forest the whole northern part of the sky appeared covered with fire… At that moment there was a bang in the sky and a mighty crash… The crash was followed by a noise like stones falling from the sky, or of guns firing. The earth trembled."
But if that is true, how is it that such a "large space rock" did not impact the Earth?
In February 2013, a large space rock, about half the size of the theorized Tunguska meteoroid, entered Russian airspace again, this time over the Chelyabinsk Oblast. Technically known as a "superbolide," it detonated in the sky with the energy equivalent of roughly 33 Hiroshima bombs. (Tunguska was flattened by an energy output of roughly 185 Hiroshima bombs.) It damaged hundreds of buildings in 10 major cities and sent over a thousand people to hospital.
In "Chelyabinsk Airburst, Damage Assessment, Meteorite Recovery and Characterization," which was published in Science in 2013, the scientists noted that the composition of the Chelyabinsk meteorites recovered were chondritic, 10 percent of their composition being that of iron. The report even acknowledged that no meteorite evidence had been recovered at the Tunguska site.
Of course, this does not mean that there are no meteorites from the event, just that none have as yet been discovered. And yet, it is unclear if there will ever be any, because a superbolide the size of the Tunguska event meteoroid need not have been composed of materials that would have ever made it to ground, all evidence of its existence disintegrating as it detonated in the air.
According to Denis Rogozin, senior research worker at Krasnoyarsk Research Center Siberian Branch of The RAS, the results of the Lake Cheka study will be published on July 17, which is the anniversary of the Tunguska event.
[Featured Image by Vokrug Sveta/Wikimedia Commons Public Domain]