Tunguska cosmic body (TCB) was a comet, containing organic matter, says Russian scientist, the fellow of Troitsk Institute of Innovative and Thermonuclear Research.
      
      The scientist reports that the TCB was a comet, containing organic matter, which was heated after entering Earth’s atmosphere, and organic matter started decomposing intensively and emitting carbon dioxide.
      
      The scientist also showed the results of chemical analysis of particles found in wood and soil – their composition reminded that of the Halley’s comet, studied by means of “Vega” spaceship.
      
      The scientists are still unable to perform total identification of the TCB chemical composition, but they are sure that some high-temperature process (an explosion) had definitely taken place.
      
      Source: ITAR-TASS

Jesse :
Why hasn't anyone ever suggested it was a ball of frozen gas such as natural gas or something like propane or methane? I worked in the oil field most of my life. If you have ever seen a propane blevy, the mock up pictures of the Tunguska explosion made from eye witness accounts will definitely seem similar. I'm watching a special about it on TV right now. They suggested that a ball of such frozen gas could never penetrate so far into the atmosphere. How do you know that? AND if it were laced with some soft rock that deflected some of the reentry heat the ball could have almost made it to the ground before breaking apart and exploding. AND the soft rock which was scattered around might have been mistaken for local material. Especially if the scientists all had tunnel vision and were ONLY searching for iron fragments. There might not have been anything that dense in the ball. And who knows just how hard frozen the thing might have been. I think it was something flammable that was frozen hard enough to get almost to the ground before exploding.

Added: 20 March 2007 22:25

dave :
If a Atomic type explosion occured then why is the vegetation still alive..etc trees, grass ie..

Added: 22 March 2007 08:59

alex :
Tunguska was assumed to be a dirty snowball -may be with solid ice and some soft rocks (hondrides?) in its core. Kinetic energy of Tunguska is estimated in tens of MT TNT range (~10^17 J), mass - in 10^8 kg, size - in km range. Snowbal likely evaporated (exploded) at some 20 km altitude or so - just because it has plenty of kinetic energy which quickly went into heat due to slowing in progressively dense atmosphere. Intense heat ignited some vegetation, shock wave made it to the ground and cause some forest leveling in few hundred square kilometers - effect similar to comparable nuclear explosion high in atmosphere. It is unlikely that most of snowball was made of methane or ethane or other low boiling temperature gas - because a comet moving with 30-80 km/sec spends a few weeks at the distance from Sun comparable to Earth (just before impact) - where sun's radiation flux is ~ 1 kw/m^2. Sunlight with that intensity for that long would causes evaporation of most low-temp stuff from that small comet. So, it still was likely a snowball/icy chunk with volatile organic matter as a minor part.

Added: 26 March 2007 22:37