[meteorite-list] Tunguska Event

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:48 2004
Message-ID: <200403100108.RAA14264_at_zagami.jpl.nasa.gov>

http://www.communitypress-online.com/template.php?id=13270&RECORD_KEY(News)=id&id(News)=13270

Meteorite crash explored by astronomical society
by Kate Everson
The Community Press Online Daily (Canada)
March 9, 2004

In the early morning hours of June 30, 1908, a huge fireball streaked
across the Siberian sky and crashed into the Earth.

"The sky split apart and a great fire appeared," said one eyewitness in
Vanavara, Russia. "It became so hot that one couldn't stand it. There was a
deafening explosion and my friend was blown over the ground across a
distance of six metres. As the hot wind passed by, the ground and the huts
trembled. Sod was shaken loose from our ceilings and glass was splintered
out of the window frames."

What was this cosmic visitor? For years, researchers have gone back to the
site and tried to find out. Antonina Vasiliev, ten, walked with her father
Nikolai and her brother, 100 kilometres through mosquito infested swamps
and bogs to the site.

"I still remember," she told the Belleville group of the Royal Astronomical
Society at its March 5 meeting at Loyalist Pioneer building.

Antonina showed slides her father and other scientists have taken
investigating the phenomenon. Her father died in 2001 and she is dedicating
her talks to his memory. Antonina currently works as a microbiologist at a
Canadian organics company in Belleville.

The event in 1908 is called the Tunguska named after a river in Russia. The
object left a trail of light 800 kilometres long and at first nobody knew
what it was. Some thought it was an explosion of anti-matter. Others
suggested a black hole. Some even claimed it to be the work of
extra-terrestrials. But most scientists now agree it was a comet or an
asteroid.

"It was the biggest event of its kind in recorded history," Antonina said.
The power of the blast felled trees outward in a radial pattern of over
2,000 square kilometres, fires burned for weeks. The mass of the object has
been estimated at about 100,000 tons and the force of the explosion at 40
megatons of TNT, 2,000 times the force of the atomic bomb exploded over
Hiroshima in 1945. By comparison, the explosive force of the Arizona
asteroid that struck some 50,000 years ago, has been estimated at 3.5
megatons.

"Had such a cosmic body exploded over Europe instead of the desolate region
of Siberia," notes Nikolai Vasiliev in a report, "the number of human
victims would have been 500,000 or more, not to mention the ensuing
ecological catastrophe."

Vasiliev stresses why continued investigations of the Tunguska event are
important. "Because it will happen again, sometime."

Antonina adds that with research they can make predictions and be ready.
She urged members of the astronomical society to study the event themselves
by researching old news reports around the world for any mention of unusual
sky events or appearances during the five-day period before and after June
30, 1908. Any information should be reported to Professor Roy Gallant at
the University of Southern Maine, <rgallant_at_usm.maine.edu>, or contact
Antonina at <antonina55_at_yandex.ru> or (613) 968-9501.

It was noted that following the Tunguska explosion, unusually colourful
sunsets and sunrises caught the world's attention and were reported in many
countries including western Europe, Scandinavia, Russia and western
Siberia. The New York Times of July 3, 1908, reported "remarkable lights"
being observed in the "northern heavens." Disturbances in the Earth's
magnetic field were reported 900 kilometres southeast of the epicentre. The
seismograph station some 4,000 kilometres west in St. Petersburg recorded
tremours, as did more distant stations around the World.

However, most thought it was just an earthquake, and no one went to
investigate until 19 years later. The shaman chief of the Tungus people
(Evenks) had for years virtually sealed off the region, proclaiming it
"enchanted." The Evenks had been fearful of further enraging the gods whose
wrath they believed was responsible for the explosion.

The first expedition in 1927 was led by a Russian scientist named Leonid
Kulik, the founder of meteorite science in Russia. Since then, 34
expeditions have been taken, many entering the site by helicopter.

There have been a series of interesting biological consequences of the
explosion, including accelerated growth of biomass in the region of the
epicentre, as well as an increase in mutations along the trajectory.
Abnormalities have been found in the Rh blood factor of the Evenks people,
and genetic abnormalities in species of insects and plants.

The resin of trees felled by the blast has been analyzed to include cosmic
matter such as calcium, iron-nickel, silicates, cobalt and lead. Certain
asteroids contain such matter, but if it was an asteroid where was the
crater and the large asteroid fragments? Scientists suggest it may have
been pulverized on exploding or skipped back into the atmosphere.

A number of scientists favour the comet theory. Large blocks of peat
samples from the epicentre have been found with isotopic abnormalities that
also occur in the upper atmosphere and are presumed to be cometary dust.
Vasiliev and his colleagues have managed to save 4,000 square kilometres of
the Tunguska region as a national reserve for the next 20 years. Log onto
the web site for more information at www.galisteo.com/tunguska.
Received on Tue 09 Mar 2004 08:08:50 PM PST