[meteorite-list] What's Hitting Earth?

From: Dave Myers <whitefalcons007_at_meteoritecentral.com>
Date: Wed, 2 Mar 2011 08:13:06 -0800 (PST)
Message-ID: <532306.52238.qm_at_web110110.mail.gq1.yahoo.com>

Hi John and list,

I also read a post on here a year ago, where someone said (I think) on average
that 2 meteorites land per-square mile
every 1000 years??? Is this figure also true. It seems high to me.

Dave



----- Original Message ----
From: John Hendry <pict at pict.co.uk>
To: Meteorite List <meteorite-list at meteoritecentral.com>
Sent: Wed, March 2, 2011 5:43:21 AM
Subject: [meteorite-list] What's Hitting Earth?



>Are there papers supporting the 100 tons per day figure hitting the
>atmosphere? Of that mass what proportion hits the surface? How are these
>figures arrived at?
>Can anyone point me to relevant references please?
>Thx,
>John
>
>
>
>On 01/03/2011 19:40, "meteoritefinder at yahoo.com"
><meteoritefinder at yahoo.com> wrote:
>
>>Yeah, Ron, like you, I thought this was newsworthy and I posted this to
>>the List about? 20 hrs ago. But no discussion here at all since then.
>>Strange.
>>Robert Woolard
>>
>>Sent from my iPhone
>>
>>On Mar 1, 2011, at 7:21 PM, Ron Baalke <baalke at zagami.jpl.nasa.gov>
>>wrote:
>>
>>>
>>>
>>>http://science.nasa.gov/science-news/science-at-nasa/2011/01mar_meteorne
>>>t
>>>work/
>>>
>>> What's Hitting Earth?
>>> NASA Science News
>>>
>>> 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."
>>>
>>> Groups of smart cameras in the new meteor network triangulate the
>>> fireballs' paths, and special software^1 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.
>>>
>>> "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
>>> nationwide^2 . 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."
>>>
>>> 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 at 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
>>> <http://fireballs.ndc.nasa.gov/> to find out what you saw!
>>>
>>>
>>> Author: Dauna Coulter
>>> Editor: Dr. Tony Phillips
>>> Credit: Science at 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.
>>>
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Received on Wed 02 Mar 2011 11:13:06 AM PST