In 1908, a sudden explosion flattened 2,000 square kilometers of Siberian forest, destroying 80 million trees. One hundred and twelve years later the exact cause remains a mystery. The Tunguska event is one of the most speculated-about anomalous events of all-time and, while scientists firmly believe that a meteor exploding some 5 to 10 kilometers above the Earth's surface is to blame, they don't have any direct evidence. This has led to the usual sort of wild and baseless (although extremely fun) speculation involving everything from aliens to secret weapons tests.
Scientists from four major Russian scientific institutes—the Novosibirsk Institute of Nuclear Physics, Novosibirsk Institute of Geology and Mineralogy, Tunguska Nature Reserve, and Krasnoyarsk Biophysics Institute—are now hoping to solve the Tunguska mystery once and for all. Dr. Arthur Meidus, deputy director of the Tunguska Nature Reserve, says:
"The mystery of the Tunguska Catastrophe worries both the scientists and the public. The meteorite is not here as a physical body, but the traces of the extremely powerful explosion are, which is what is currently studied by researchers. Many of us still hope to unravel the scenario of 1908 disaster."
To do this, the scientists are looking at the bottom of a lake. The sediments at the bottom of Lake Zapovednoye, approximately 40km away from the assumed epicenter of the blast, may contain evidence of a meteor explosion—if, in fact, one occurred. Dr. Meidus says:
"Although this lake is outside the territory that was affected in 1908, it is of great interest. It is deep, and silty sediments that have accumulated here, do not mix, or subside.
Spring-autumn waste waters and the Lakura River brought traces of the Tunguska catastrophe to this lake, because the event was accompanied by massive wildfires and emissions of both planet and space origin."
Using fun science words like X-ray fluorescence and synchrotron radiation, the scientists hope to be able to detect particles of extraterrestrial origin in the layers of sediment that date to the Tunguska event. Dr. Meidus says they have already been able to determine which layers come from the year of the blast. They are looking specifically at the layers from 1908 through 1910, as meteor particles may have washed into the lake in the two years following the explosion. Dr. Meidus says:
"We discovered a distinguishing light-coloured layer in sediments of Lake Zapovednoye the content of which - an increased content of potassium, titanium, rubidium, yttrium, and zirconium - allows to tie it to the consequences of the Tunguska bolide explosion. This way we know which layer of sediments might contain particles of extraterrestrial origin.
‘The next stage implies search for micro-particles with unusual composition with the use of synchrotron radiation. Now we know where to look for them.
‘If there is extraterrestrial substance, it will be in the 1908-1910 layer."
It will be interesting to see if they find what they're looking for. If they do discover particles from some extraterrestrial object in the lake, it would put a damper on all the fun speculation. But they haven't found it yet and mysteries like the Tunguska event seem to enjoy remaining mysteries.