NASA Tracks Russian Meteor Plume   
       
   August 15, 2013:  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 the atmospheric aftermath. The explosion created a   
   never-before-seen belt of "meteor dust" that circulated through the   
   stratosphere for at least three months.   
       
   https://www.youtube.com/watch?v=Q9KwK0izt5c   
       
   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. Play the video   
       
   Shortly after dawn on Feb. 15, 2013, the meteor, or bolide, measuring 18   
   meters  across and weighing 11,000 metric tons, screamed into Earth's   
   atmosphere at 18.6 km/s (41,600 mph). Burning from the friction with Earth's   
   thin air, the space rock exploded 23 km above Chelyabinsk, releasing more than   
   30 times the energy from the atom bomb that destroyed Hiroshima. Video:  What   
   Exploded over Russia?   
       
   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 the NASA-NOAA Suomi National Polar-orbiting Partnership 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 Suomi detected the plume high in the atmosphere   
   at an altitude of about 40 km, quickly moving east at about 300 kph (190 mph).   
       
   http://npp.gsfc.nasa.gov/   
       
   An artist's concept of the Suomi NPP satellite. Home pageThe 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   
   dust from] the bolide and understand its evolution as it moves around the   
   globe."   
       
   The full implications of the study remain to be seen. Every day, tens of   
   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."   
       
   Credits:   
       
    Production editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More information:   
       
   What Exploded over Russia?  -- ScienceCast video   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.94   
    * Origin: NCS BBS - Houma, LoUiSiAna (1:3828/7)