Details Emerging On Tunguska Impact Crater

#space_on_irc.freenode.net (Dusty) writes "Lake Cheko in Siberia has been noted as the probable crater of the 1908 Siberian Tunguska event. This news was discussed here in December, but details on the crater were scant. Now a new paper written by Luca Gasperini, Enrico Bonatti, and Giuseppe Longo (the same team in Bologna, Italy that made news in December) has a horde of new details on the supposed crater. The team visited Lake Cheko complete with their own catamaran and completed ground-penetrating radar maps, side-scanning sonar images, aerial images, and some sample collection of Lake Cheko. Intriguingly, they also imaged an object under the sediment that may be a fragment of the impacting body. Their paper (PDF) includes a lot more details including images, side-scanning sonar image, a 3-D view of the lake, a morphobathymetric map. It's an interesting read, these dudes are good. They plan to return this summer and drill the core if weather permits, hopefully answering the question once and for all." The same team also has a more discursive article in the current Scientific American that includes some detail on the working conditions in the Siberian summer. Think: mosquitos.

Go Slashdot !!!

[Anonymous Coward]

This is what I'm talking about!

No more of that crap from idle on the front page, this is what you should be posting! This makes my geekiness tingle, this is what keeps me coming back. Please, for the love of God, more of the same!

An alternative hypothesis

[D. J. Keenan]

The extra-terrestial impactor (i.e. asteroid/comet) hypothesis has been around for a long time. It has been questioned for several reasons. In particular, (i) there were bright/white nights before the event, and (ii) debris has been found in crash sites from meteorites 10000 times lighter, whereas there is none at Tunguska.

For more details and an alternative explanation, see the following.
W. Kundt (2001), "The 1908 Tunguska catastrophe [ias.ac.in]", Current Science, 81: 399-407.

Dr. Kundt is at the University of Bonn. Briefly, his hypothesis is that there was a days-long leakage of natural gas, from Earth; the gas rose up and was eventually ignited by lightning. This seems to fit the evidence better.

In an earlier discussion on Slashdot, someone posted a comment [slashdot.org] claiming that there was a similar explosion of natural gas in Texas in 1992. (I googled, but could find no evidence.)

I do not understand the geology well, but it does not seem that the Italian researchers (cited in TFA) have found evidence against Kundt's hypothesis.

well...

[murka]

Wow, catamaran is an argument. My mother [irkutsk.com] [In Russian] was on the first "Complex Independent Expedition" and on the few following ones in the 60s. (She is available for questions). Many many scientists spent years on the spot, checking all possible hypothesises from a crashed space craft to an exploded ice comet. The result: no actual material ever found and the forest damage shows that the explosion took place far above the surface. BTW, there are plenty of lakes there, as the area is pretty wet. Pick one on Google Maps to fit your favorite hypothesis.

Re:Very interesting article

[jmichaelg]

The grandparent may be thinking of this event. [wikipedia.org] Had the bollide arrived a few hours earlier, it would have exploded over either Pakistan or India who were already shooting at each other over Kashmir. The explosion was twice as large as the Hiroshima blast.

Whether both sides would have held their fire in that event is hard to tell.

Mosquitos ++

[RockDoctor]

the working conditions in the Siberian summer. Think: mosquitos.

Mosquitoes ad nauseam.

Mosquitoes to the point of anaphylaxis (well, that was what the rig's medic was afraid of, which is why he evacuated me back to the base camp).

Mosquitoes that can maintain eye contact at a meter range (i.e you can see it's eyes at a meter range) through the window of the car, then launch an assault on this nice juicy mammal, only being stopped by the glass of the window.

Mosquitoes that can keep pace with you while driving at 40km/hr on a dirt road.

Mosquitoes that can bite you through a leather glove, 20 times in one evening's work. They choose the clipboard hand, because you can't swat with that and get your work done.

Don't get me wrong - Siberia is interesting, but don't forget the industrial strength insect repellent and the appropriate clothing. If you don't know what's appropriate, ask a bee keeper. And don't forget the vaccination against tick-borne encaphalitis (which includes Lyme disease, I believe), which takes several weeks to become effective.

Re:We can check it for serial numbers :)

[NeilTheStupidHead]

If I remember correctly, most of the models depict an asteroid exploding in mid-air. Certainly, a great deal of the debris would end up on the ground, but falling debris would have a very different impact (no pun intended, unless it's funny) than a single large strike.

Re:Very interesting article

[geobeck]

My fear is that someone would mis-interpret an incoming meteor as a nuclear weapon and initiate a launch on their perceived threats.

Not a fear likely to be realized, fortunately. If a major strategic city is vaporized, it's almost a certainty that it was destroyed by a strategic nuke. If a random area of countryside or open ocean is vaporized, it's almost certainly a meteotie/asteroid/comet.

The percentage of Earth's surface covered by major strategic cities is miniscule. If an asteroid ever does hit one square on, that will be a sign that someone up there has decided to pull another Sodom & Gamorrah.

Carolina bays

[Solandri]

There's a similar mystery right here in the U.S. The Carolina bays [wikipedia.org] are elliptical depressions scattered throughout the southern Eastern U.S. seaboard [google.com]. They're mostly filled with water so form small lakes, ponds, or wetlands. But they're all approximately the same shape and orientation (but not size). A variety of theories have been posed as to their origin, including a glancing comet strike (shallow angle impacts produce elliptical craters, not round). They're not as well-known as the Tunguska event, but they're a lot more accessible if you wanted to visit a mysterious possible impact site.

Re: Mosquitos ++

[mev]

That is a little more severe than I encountered when bicycling across Russia last summer.

Between end of May and mid-July, we traveled through the West-Siberian plain. We generally encountered four major types of flying insects there:

• Big biting flies, 2-3cm; could keep up with a 20km/hr cyclist. Got situated before biting, so if you were quick enough, could swat them away. Seemed to be gone if it was too cold.
  
• Mosquitoes; did not keep up with a 20km/hr cyclist. Particularly active in morning and evening.
  
• Small biting flies; not a problem when traveling but a problem when camping
  
• Small non-biting flies; not a big problem
  

Depending on where we camped, we also had problems with ants.

The density of the mosquitoes and biting flies were approximately the same as I've encountered on previous bicycle trips in northern Yukon and Alaska. However, they were much more widespread and much more continuous, day after day. Every place we camped for a month and a half, we had insects. Sometimes worse, but always present. (That was not the case in Alaska.) If one were working in one place or traveling slower than 20km/hr, I could see why that would be even worse.

However, either the situation is even worse where RockDoctor was at than where I cycled or there is (slight) exageration here, e.g. I encountered biting flies that could do 20km/hr but not mosquitoes.