[meteorite-list] Around the World in Four Days: NASA Tracks Chelyabinsk Meteor Plume

[Ron Baalke]

http://www.nasa.gov/content/goddard/around-the-world-in-4-days-nasa-tracks-chelyabinsk-meteor-plume/ 

Around the World in Four Days: NASA Tracks Chelyabinsk Meteor Plume
Kathryn Hansen
NASA's Earth Science News Team
Aug. 14, 2013

[Video]
A meteor weighing 10,000 metric tons exploded 14 miles above Chelyabinsk, 
Russia, on Feb. 15, 2013. Unlike similar past events, this time scientists 
had the sensitive instruments on the Suomi NPP satellite to deliver unprecedented 
data and help them track and study the meteor plume for months.

Atmospheric physicist Nick Gorkavyi missed witnessing an event of the 
century last winter when a meteor exploded over his hometown of Chelyabinsk, 
Russia. From Greenbelt, Md., however, NASA's Gorkavyi and colleagues witnessed 
a never-before-seen view of the atmospheric aftermath of the explosion.

Shortly after dawn on Feb. 15, 2013, the meteor, or bolide, measuring 
59 feet (18 meters)  across and weighing 11,000 metric tons, screamed 
into Earth's atmosphere at 41,600 mph (18.6 kilometers per second). Burning 
from the friction with Earth's thin air, the space rock exploded 14.5 
miles (23.3 kilometers) above Chelyabinsk.

The explosion released more than 30 times the energy from the atom bomb 
that destroyed Hiroshima. For comparison, the ground-impacting meteor 
that triggered mass extinctions, including the dinosaurs, measured about 
6 miles (10 kilometers) across and released about 1 billion times the 
energy of the atom bomb.

Some of the surviving pieces of the Chelyabinsk bolide fell to the ground. 
But the explosion also deposited hundreds of tons of dust up in the stratosphere, 
allowing a NASA satellite to make unprecedented  measurements of how the 
material formed a thin but cohesive and persistent stratospheric dust 
belt. 

"We wanted to know if our satellite could detect the meteor dust," said 
Gorkavyi, of NASA's Goddard Space Flight Center in Greenbelt, Md., who 
led the study, which has been accepted for publication in the  journal 
Geophysical Research Letters. "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 and colleagues combined a series of satellite measurements with 
atmospheric models to simulate how the plume from the bolide explosion 
evolved as the stratospheric jet stream carried it around the Northern 
Hemisphere.

About 3.5 hours after the initial explosion, the Ozone Mapping Profiling 
Suite instrument's Limb Profiler on the NASA-NOAA Suomi National Polar-orbiting 
Partnership satellite detected the plume high in the atmosphere at an 
altitude of about 25 miles (40 kilometers), quickly moving east at about 
190 mph (more than 300 kph).

The day after the explosion, the satellite detected the plume continuing 
its eastward flow in the jet and reaching the Aleutian Islands. Larger, 
heavier particles began to lose altitude and speed, while their smaller, 
lighter counterparts stayed aloft and retained speed - consistent with 
wind speed variations at the different altitudes.

By Feb. 19, four days after the explosion, the faster, higher portion 
of the plume had snaked its way entirely around the Northern Hemisphere 
and back to Chelyabinsk. But the plume's evolution continued: At least 
three months later, a detectable belt of bolide dust persisted around 
the planet.

The scientists' model simulations, based on the initial Suomi NPP observations 
and knowledge about stratospheric circulation, confirmed the observed 
evolution of the plume, showing agreement in location and vertical structure.

"Thirty years ago, we could only state that the plume was embedded in 
the stratospheric jet stream," said Paul Newman, chief scientist for Goddard's 
Atmospheric Science Lab. "Today, our models allow us to precisely trace 
the bolide and understand its evolution as it moves around the globe."

The full implications of the study remain to be seen. Every day, about 
30 metric tons of small material from space encounters Earth and is suspended 
high in the atmosphere. Even with the addition of the Chelyabinsk debris, 
the environment there remains relatively clean. Particles are small and 
sparse, in contrast to a stratospheric layer just below where abundant 
natural aerosols from volcanoes and other  sources collect.

Still, with satellite technology now capable of more precisely measuring 
tiny atmospheric particles, scientists can embark on new studies in high-altitude 
atmospheric physics. How common are previously unobservable bolide events? 
How might this debris influence stratospheric and mesospheric clouds?

Scientists previously knew that debris from an exploded bolide could make 
it high into the atmosphere. In 2004, scientists on the ground in Antarctica 
made a single lidar observation of the plume from a 1,000-ton bolide.

"But now in the space age, with all of this technology, we can achieve 
a very different level of understanding of injection and evolution of 
meteor dust in atmosphere," Gorkavyi said. "Of course, the Chelyabinsk 
bolide is much smaller than the 'dinosaurs killer,' and this is good: 
We have the unique opportunity to safely study a potentially very dangerous 
type of event."