A portion of Chelyabinsk's dust plume circled
Earth in just four days, as shown in this image
based on modelling and the NPP Suomi satellite's
observations
(NASA's Goddard Space Flight Center Scientific
Visualization)
When a meteor exploded over the Russian
city of Chelyabinsk in February, pieces of
the bus-sized space rock hit the ground
while its detonation shattered windows, set
off car alarms and injured more than 1,000
people.
Masked in the chaos, however, was an
enormous plume of dust that the Russian
meteor left behind in Earth's atmosphere.
This cloud, which had hundreds of tons of
material in it, was still lingering three
months after the Feb. 15 explosion, a new
study has found. Scientists created a
video of the Russian meteor explosion's dust
cloud to illustrate the phenomenon.
'We saw the formation of a new dust
belt in Earth's stratosphere.'
- NASA Goddard atmospheric physicist
Nick Gorkavyi
"Thirty years ago, we could only state
that the plume was embedded in the
stratospheric jet stream," Paul Newman,
chief scientist for NASA Goddard Space
Flight Center's atmospheric science lab,
said in a statement. "Today, our models
allow us to precisely trace the bolide and
understand its evolution as it moves around
the globe." [See
photos of the Feb. 15 Russian fireball]
Chasing dust
The Russian meteor, which weighed
11,000 metric tons when it hit the
atmosphere, detonated about 15 miles above
Chelyabinsk. The explosion sent out a burst
of energy 30 times greater than the atom
bomb that leveled Hiroshima during World War
II.
Some of the asteroid's remnants crashed
to the ground, but hundreds of tons of dust
remained in the atmosphere. A team led by
NASA Goddard atmospheric physicist Nick
Gorkavyi, who is from Chelyabinsk, wondered
if it was possible to track the cloud using
NASA's Suomi NPP satellite.
"Indeed, we saw the formation of a new
dust belt in Earth's stratosphere, and
achieved the first space-based observation
of the long-term evolution of a bolide
plume," Gorkavyi said in a statement.
Initial measurements 3.5 hours after the
meteor explosion showed the dust 25 miles
high in the atmosphere, speeding east at 190
mph.
Russian officials were still cleaning up
in Chelyabinsk when, four days after the
explosion, the higher portion of the plume
reached all the way around Earth's northern
hemisphere. Even three months into the
study, Suomi still saw a "detectable belt"
of dust circling the globe, researchers
said.
Putting it in perspective
Tracking the plume also revealed some
insights into how particles behave in
Earth's atmosphere. Heavier particles,
for example, moved more slowly as they
dropped closer to Earth in an area with
lower wind speeds. Lighter particles
maintained speed and altitude, consistent
with predictions of wind velocities at their
heights.
While the plume was easily detectable, it
was by no means extraordinarily dense, NASA
researchers noted. About 30 metric tons of
space dust hits the Earth every day on
average. Also, volcanoes and other natural
Earth sources contribute far greater numbers
of particles to the stratosphere.
The study is ongoing, with potential
research directions including looking at
whether or not meteor debris can affect
cloud formation in the stratosphere and
mesosphere.
A paper based on the work so far has been
accepted for publication in the journal
Geophysical Research Letters.