Tunguska crater found?

Here’s something you didn’t know and probably won’t care about: Before starting up Hot Air with the divine Mrs. M and Allahpundit I worked for the Hubble Space Telescope project, and among my last assignments there I produced a multimedia show about the Tunguska event. As those things usually go, I had to write a script about the 1908 event, in which something big exploded over a remote region of Russia and flattened about 800 acres square miles of woods. Over the course of writing the script I researched the event extensively. By the end of it, I had become convinced that the thing that exploded was probably a comet that grazed into the atmosphere and detonated due to friction. But it could have been a porous asteroid too. Basically, it had to be fairly large but also fairly light, since it didn’t leave a crater but did leave a very large area of obvious devastation.

The problem with that conclusion is, it may have left a crater.

Italian researchers now think they’ve found a smoking gun: The 164-foot-deep Lake Cheko, located just 5 miles northwest of the epicenter of destruction.

“When we looked at the bottom of the lake, we measured seismic waves reflecting off of something,” said Giuseppe Longo, a physicist at the University of Bologna in Italy and co-author of the study. “Nobody has found this before. We can only explain that and the shape of the lake as a low-velocity impact crater.”

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“Expeditions in the 1960s concluded the lake was not an impact crater, but their technologies were limited,” Longo said. With the advent of better sonar and computer technologies, he explained, the lake took shape.

Going a step further, Longo’s team dove to the bottom and took 6-foot core samples, revealing fresh mud-like sediment on top of “chaotic deposits” beneath. Still, Longo explained the samples are inconclusive of a meteorite impact.

If it left a crater, it probably wasn’t a comet. The Deep Impact mission slammed into a comet a couple of years ago (yeah, I was tangentially involved in that too–I was at Hubble’s office on earth when it was used to spy the impact’s results, and I helped get those results to the outside world as fast as possible) and found that the comet that it punched, Tempel 1, was very light and fluffy, like a big ball of talcum powder. That’s probably too insubstantial to leave much of a crater, if any at all. So that would make an asteroid the more likely illegal alien to have smashed into rural Russia.

As for my multimedia show, for all I know it’s still playing in museums and planeteriums around the world. And if these guys are right about the crater, I was probably wrong about what caused it. But I wrote the show loosely enough, so I should be covered. It could probably use an update though.

Update: Down in the comments, I mentioned a very good book I read a couple of years ago on the subject of comet and asteroid impacts etc, but couldn’t think of the title. I racked my brain and came up with it — Rain of Iron and Ice, by John S. Lewis. Great book. Very scary computer modeling in the appendix.

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