What's Hitting Earth?   
       
   March 1, 2011: Every day about 100 tons of meteoroids -- fragments of dust and   
   gravel and sometimes even big rocks - enter the Earth's atmosphere. Stand out   
   under the stars for more than a half an hour on a clear night and you'll   
   likely see a few of the meteors produced by the onslaught. But where does all   
   this stuff come from? Surprisingly, the answer is not well known.   
       
   Now NASA is deploying a network of smart cameras across the United States to   
   answer the question, What's Hitting Earth?   
       
   Did that meteor you saw blazing through the sky last night come from the   
   asteroid belt? Was it created in a comet's death throes? Or was it a piece of   
   space junk meeting a fiery demise?   
       
   "When I get to work each morning and power up my computer, there's an email   
   waiting with answers," says William Cooke, head of NASA's Meteoroid   
   Environment Office. "And I don't have to lift a finger, except to click my   
   mouse button."   
   [...]   
   A Southern Delta Aquarid fireball streaks over one of the network cameras in   
   July 2010: movie.   
       
   Groups of smart cameras in the new meteor network triangulate the fireballs'   
   paths, and special software1 uses the data to compute their orbits and email   
   Cooke his morning message.   
       
   "If someone calls me and asks 'What was that?' I'll be able to tell them.   
   We'll have a record of every big meteoroid that enters the atmosphere over the   
   certain parts of the U.S. Nothing will burn up in those skies without me   
   knowing about it!"   
       
   In other U.S. meteor networks, someone has to manually look at all the   
   cameras' data and calculate the orbits - a painstaking process.   
   [...]   
   The orbit of the Southern Delta Aquarid meteor (red) was a good match to that   
   of the parent comet (blue). "With our network, our computers do it for us -   
   and fast," says Cooke.   
       
   The network's first three cameras, each about the size of a gumball machine,   
   are already up and running. Cooke's team will soon have 15 cameras deployed   
   east of the Mississippi River, with plans to expand nationwide2. Cooke is   
   actively seeking schools, science centers, and planetaria willing to host his   
   cameras. Criteria are listed in the notes at the end of this story.   
       
   In addition to tracking fireballs and their orbits, Cooke's system gives him   
   other valuable information.   
       
   "It provides data on meteor speed as a function of size - and this is critical   
   to calibrating the models we use in designing spacecraft."   
       
   Meteorite hunters will reap benefits too. By determining a bright fireball's   
   trajectory through the atmosphere, the network's software can calculate   
   whether it will plunge to Earth and pinpoint the impact location fairly   
   precisely.   
       
   "And when we collect the meteorite chunks, we'll know their source. I could be   
   holding a piece of Vesta in my hand.3 It would be like a free sample return   
   mission!"   
       
   Opportunities like that, however, will be rare. "Most meteorites fall in the   
   ocean, lakes, forests, farmer's fields, or the Antarctic," says Rhiannon   
   Blaauw, who assists Cooke. "And the majority of those meteorites will never be   
   found. But our system will help us track down more of them."   
   [...]   
   NASA's Smart Meteor Network is catching more than fireballs. In this movie, a   
   bird stops to rest on one of the cameras in Georgia. Apparently, spiders like   
   the cameras, too.   
   All cameras in the network send their fireball information to Cooke and to a   
   public website, fireballs.ndc.nasa.gov. Teachers can contact Cooke at   
   William.J.Cooke@nasa.gov to request teacher workshop slides containing   
   suggestions for classroom use of the data. Students can learn to plot fireball   
   orbits and speeds, where the objects hit the ground, how high in the   
   atmosphere the fireballs burn up, etc.   
       
   Cooke gives this advice to students and others who want to try meteor watching   
   on their own:   
       
   "Go out on a clear night, lie flat on your back, and look straight up. It will   
   take 30 to 40 minutes for your eyes to become light adapted, so be patient. By   
   looking straight up, you may catch meteor streaks with your peripheral vision   
   too. You don't need any special equipment -- just your eyes."   
       
   One more thing -- don't forget to check the website to find out what you saw!     
       
   Author: Dauna Coulter | Editor: Dr. Tony Phillips | Credit: Science@NASA   
       
   More Information   
   (1) The smart meteor network uses ASGARD (All Sky and Guided Automatic   
   Realtime Detection) software, developed at the University of Western Ontario   
   with both NASA and Canadian funding, to process the information and perform   
   the triangulation needed to determine the orbits and origins of the fireballs.   
   The Southern Ontario Meteor Network, or SOMN, composed of seven cameras, also   
   uses the ASGARD system.   
       
   (2) The cameras will be deployed in clusters of 5. One group will be spread   
   over the Southeast US, another in the Ohio and Kentucky area (to overlap with   
   the Southern Ontario Meteor Network, or SOMN), and another along the Atlantic   
   coast in the NorthEast. "Our hope is that at least one of the three regions   
   will have clear skies at any given time."   
       
   Here are the criteria that must be met for a location to be considered as a   
   camera site:   
       
   1. Location east of the Mississippi River   
   2. Clear horizon (few trees)   
   3. Few bright lights (none close to camera)   
   4. Fast internet connection   
       
   (3) The meteorite will have been altered by its journey, so it is not a   
   pristine sample, but, says Cooke, it is a good enough sample to give you basic   
   characteristics of the non-volatiles.   
       
       
   Regards,   
       
   Roger   
      
   --- D'Bridge 3.59   
    * Origin: NCS BBS (1:3828/7)