[meteorite-list] One Month On, Russia's Meteor Still A Hot Topic

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 14 Mar 2013 14:33:05 -0700 (PDT)
Message-ID: <201303142133.r2ELX5qP000677_at_zagami.jpl.nasa.gov>

http://www.rferl.org/content/russia-meteorite-chelyabinsk-findings/24927784.html

One Month On, Russia's Meteor Still A Hot Topic
Andy Heil
Radio Free Europe
March 13, 2013

It's been nearly a month since a fireball lit up the crisp blue skies
over Ural Russia as an unusually large meteor plunged to earth, creating
a shockwave that blew out windows and injured more than 1,200 people.

The event seared its way into the national consciousness and drew
comparisons to the biggest meteor impact ever recorded, the so-called
Tunguska event over Siberia more than a century ago.

It also mobilized Russia's and other scientific communities, and
sparked a public and private rush to cash in on the passing fame that
this rare event offered.

But this week it buttressed Russia's determination that humankind should be
more agressively pursuing ways to prevent the kind of catastrophic collision
that many think wiped out the dinosaurs 65 million years ago.

Speaking to a special session of the upper house of the Russian parliament,
the Federation Council, officials from that country's space agency, nuclear
agency, and astronomical institute pressed their case for billions of
dollars of investment to prepare for what could eventually be nuclear
strikes to deflect or take out approaching comets or asteroids.

They cited the Apophis asteroid's projected near-miss in 2036 and said
concrete measures to monitor and possibly intercept an asteroid could be
in place as soon as 2018. (U.S. space agency NASA has said there's nothing
to worry about from Apophis.)

"The unexpected appearance of out-of-space objects close to the Earth is not
an exception but a typical situation and we may have very little time to make
a decision to counteract," Boris Shustov, director of Russian Academy of
Sciences Astronomy Institute, chairman of the experts' group for space threats,
said, according to Reuters.

The meteor that exploded over Chelyabinsk, Russia on February 15 was thought
to have been around 15 meters in diameter before hitting the atmosphere
and breaking into many pieces, with its largest chunk most likely plunging
into Lake Chebarkul.

The tracking and avoidance systems under study or in their early stages so far
are generally thought to be aimed at tackling larger fragments. And while the
Russian meteor was indeed terrifying to those in its immediate vicinity, the
urgency of calls for impact-avoidance systems are tempered by the historical
record -- the Chelyabinsk event was the largest reported meteor since Tunguska
in 1908.

Still, the Russian scientists embraced apocalyptic language in their briefing
for lawmakers.

"We will have a very limited amount of time to prevent the collision. About a
year, including the launch of an interceptor and separating fragments in space,"
Oleg Shubin, deputy director for nuclear weapons management at nuclear agency
Rosatom said, according to Reuters. "It's also worth mentioning that an
interception of a meteorite the size of one kilometer will require the use of
nuclear explosive devices with a capacity well exceeding the megaton class."

NASA is already spending money to develop an Asteroid Terrestrial-Impact Last
Alert System (ATLAS), which its backers say could give about a day's warn
ing in cases like that in Chelyabinsk, pinpointing the area of impact within
a kilometer or two.

In late February, less than two weeks after the Russian meteor, Canada's
space agency launched a microsatellite as part of its experimental "Sentinel
in the Sky," intended to provide an early-warning system for space debris
and other near-Earth objects.

Meanwhile, the more immediate work of detailing and categorizing exactly what
happened over Chelyabinsk on February 15 has continued.

Russian researchers and volunteers are still rounding up fragments of the
meteorite that exploded over the Urals, with initial tests suggesting the event
was unusual in its size but not in its other essentials.

Researchers at Ural Federal University (UrFU) have already collected hundreds
of fragments from the area where the meteorites came down, referred to as the
"strewing field."

UrFU's Institute of Physics and Technology professor Viktor Grokhovsky, who
launched its meteorite expedition, told RFE/RL recently: "Our expedition has
made three visits to the site and found over 300 fragments, from 3 millimeters
to 150 millimeters. There have been several thousand fragments found mostly
by the local residents. The ones that could have reached the ground can
be up to half meter long."

Here's a video showing some of the fragments in detail in which Grokhovsky
describes the largest of the pieces to have been retrieved so far as weighing
1.8 kilograms (click "captions" to see English subtitles):
[Video]

He and his colleagues say the asteroid was ordinary or common chondrite, the
most common makeup of asteroids and material that's "the same age as the
Solar System -- approximately 4.5 billion years old." It consists of minerals
like olivine, pyroxene, troilite, and kamacite in combinations that aren't
found on Earth.

They and others are still searching for the largest of the chunks that plowed
into Russian ground that day.

The Chelyabinsk meteor's fiery mid-morning arrival was the most closely recorded
in history, with uploaded dash-cam and other videos of the remarkable scenes
emerging within minutes.

That visual record has allowed specialists like Pavel Spurny, from the
"fireball studies" team at the Astronomical Institute of the Czech Academy of
Sciences at Ondrejov Observatory, to plot in great detail the final airborne
seconds of the Chelyabinsk meteor. The goal is to help reconstruct the initial
object and its speed, as well as to determine its composition, what parts
of it survived, and where those pieces might lie.

Using videos calibrated with Google Maps tools, the Czechs tracked the four
largest fragments that in turn disintegrated into thousands of smaller meteorites.

Their preliminary findings were published in a letter to the International
Astronomical Union's Central Bureau for Astronomical Telegrams.

They concluded on the basis of video evidence that the Chelyabinsk meteor first
appeared at an altitude of around 92 kilometers and streaked for 11 seconds
before blowing up as a result of friction and heating around 32 kilometers above
ground.

The original asteroid was "relatively fragile in comparison with other
superbolides," or fireball meteorites, Spurny told RFE/RL.

He called it "really a unique historical event" in light of its size and its
proximity to a major population center. Spurny compared it to two other landmark
meteor events that he'd worked on in the past. The first was the so-called
Peekskill Meteor, when a chunk of asteroid streaked across the sky above the
eastern United States in October 1991 before slamming into a parked car. That
fireball (or superbolide) was caught by at least 16 video cameras, many of which
were recording a high-school football game.

The other was the Moravka meteorite incident in May 2000, named after the city in
northeastern Czech Republic where the fragments fell. The fireball from that
1,000-2,000 kilogram object's impact with the atmosphere and subsequent fall was
videotaped by at least three people.

The Czech scientists say the biggest of the Chelyabinsk pieces weighs between 200
and 500 kilograms. Asked whether they think that chunk lies below shallow Lake
Chebarkul, where a 6-meter-wide round hole was blown in the surface ice, Spurny
responded unequivocally: "Certainly. It's directly below the hole." He added that
it's likely to have come to rest "tens of meters" beneath Lake Chebarkul's 10
meters of water and 10 meters more of mud.

The prospect of finding that or other chunks of otherworldly matter has meanwhile
sparked an old-time meteorite rush in the Urals region, with residents joining
the hunt in the frozen countryside for science, profit, or simply a space "memento."

The BBC joined some of those forays into the Chelyabinsk countryside for a report
two weeks after the meteor fall:

The BBC team found four tiny stones within five minutes. Most of those fragments
found near Deputatsky are pea-sized, but some can be much bigger -- more like golf
balls.

The biggest fragment we saw weighed about 100 grams. It was found by a citizen of
Chelyabinsk, who said he had received several offers from friends in Moscow.

"It's like hunting or fishing," said one meteorite hunter. "When you see an
animal, your heart starts to beat fast, and when you're fishing -- it's
like pulling the fishing rod and thinking there's something extraordinary.
This is the same - -you see a tiny hole, try it, and here it is."

There are at least 50 offers on eBay of purported meteorites from Chelyabinsk/Chebarkul
for initial bids as low as $0.99 and up to $1,180, although most are at
the low end of the spectrum. The offers are from vendors as farflung as
Portugal, Yugoslavia, Germany, Finland, Latvia, and, of course, Russia.
The BBC has cited other online offers ranging from around $30 to 11,000
British pounds ($16,650), and "The Daily Telegraph" quoted Chinese experts
warning of bogus "meteor fragment" offers on web seller Taobao and in
other places in connection with a 10,000-pound pitch.
Received on Thu 14 Mar 2013 05:33:05 PM PDT