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Re: (meteorobs) Meteorites and Terminal velocity

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  • GeoZay@aol.com
    Dave Your point about recrystalization from reheating has merit but I believe that to form smaller crystals the iron meteorite would have to completely melt
    Message 1 of 10 , Dec 26, 2000
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      Dave>> Your point about recrystalization from reheating has merit but I
      believe that to form smaller crystals the iron meteorite would have to
      completely melt (2795 o F or 1535 o C ) then all of the meteorite would
      have the same very small crystals that make up the fusion crust.<<

      I can think of at least one instance where melting doesn't have to occur to
      have crystal structure changes in heated iron. The process of making cold
      chisels. It's been a long time since I've made one, but do recall that you
      heat up the shaped piece of iron to a red hot temperature and then dip it
      into cold water. This process results with a changed crystal structure and
      very hard metal. No melting was involved.
      GeoZay


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    • Dave English
      George, Good point about Appollo 13, but I think if you add -240o F, the temperature in the shade and +200o F, the sun side of the craft, you get -40o F, and
      Message 2 of 10 , Dec 26, 2000
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        George,

        Good point about Appollo 13, but I think if you add -240o F, the
        temperature in the shade and +200o F, the sun side of the craft, you get
        -40o F, and isn't that about the temperature they struggled with? As for
        iron, it transmitts heat more efficiently than cold, so it would be warmer.

        The other day when looking up Cherenkov Lights when the subject was
        lights in the sky, I ran across a Nasa site that was posted on 21 Nov 2000
        with the Apollo 15 flight journal, Apollo 13 isn't posted yet.
        http://www.hq.nasa.gov/office/pao/History/ap15fj/index.htm

        The tempering of iron is a manufactuing process and is more involved
        than heating and cooling. It requires that certain temperatures be used,
        heating slowly to low cherry red or a cherry red (1470o F to 1650o F),
        quenching part of the steel then polishing it while the heat transfer return
        a straw yellow to a brown yellow color to the tip (460o F to 500o F) then
        it's quenched again. The grain structure is changed during working the
        steel in preperation to tempering where the grain is drawn out in in
        repeated heatings and workings to shape the steel (Arizona Lode Gold Mines
        and Gold Mining, Bul. 137, 1967) an old friend.

        Nick Martin suggested that some combination of oxides could cause the
        meteorites to burn after being exposed to high temperatures during entry.
        Lew promply suggested to Nick that he take his idea and get out of Dodge.
        Marco now has suggested something similar but more exotic. The Mazapil
        Meteroite narrative offers an insight, "At once the corral was covered with
        a phosphoescent light, while suspended in the air were small luminous
        sparks as though from a rocket." And, "I saw this luminous air disappear,
        and there remained on the ground only such a light as is made when a match
        is rubbed." Something was going on, maybe it was the detected 0.3%
        phosphorus burning once it was ignited.

        I want to persue other projects at this time, we have to wait for science
        to answer some of our questions and ideas here.

        Dave English

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      • YoungBob2@aol.com
        In a message dated 12/27/2000 3:49:01 PM Eastern Standard Time, prospector@sd.znet.com writes:
        Message 3 of 10 , Dec 27, 2000
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          In a message dated 12/27/2000 3:49:01 PM Eastern Standard Time,
          prospector@... writes:

          <<
          The other day when looking up Cherenkov Lights when the subject was
          lights in the sky, >>

          Hi, Dave:

          Did you find any sites with info about the Cherenkov Lights? This business
          about very faint meteors, possibly internal, has always interested me.

          Thanks.

          Bob Young
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        • Dave English
          Bob Young and others interested in Cherenkov lights/radiation, I was able to find several pages of hits on the google search engine using the words Cherenkov
          Message 4 of 10 , Dec 27, 2000
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            Bob Young and others interested in Cherenkov lights/radiation, I was
            able to find several pages of hits on the google search engine using the
            words Cherenkov radiation, but some hits can be found under Cherenkov
            lights, including one of my meteorob posts- live forever on the web!:

            http://www.google.com

            My other search engines kept turning up pages of products (?). After
            reading about ten websites two of the best are:

            http://math.ucr.edu/home/baez/physics/cherenkov.html

            The UCR is the best but for more math try:

            http://Rd11.web.cern.ch/RD11/rkb/PH14pp/node26.html

            After reading the first site, I wondered if the blue meteor train/trails
            seen in Russia in 1947 and Mongolia in 1999 (8?) were products of
            Cherenkov lights? Could they account for the kilometer and plus radiation
            seen from some point meteors? Something for the experts to consider.

            Dave English
            Oceanside, California

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          • Nick Martin
            ... It was metallic dust or a porous solid made up of very poorly consolidated metal powder. Elemental phosphorus would I suppose be at least a possibility
            Message 5 of 10 , Dec 28, 2000
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              At 10:45 PM 12/26/00 -0700, you wrote:
              >George,
              >
              > Good point about Appollo 13, but I think if you add -240o F, the
              >t
              >
              > Nick Martin suggested that some combination of oxides could cause the
              >meteorites to burn after being exposed to high temperatures during entry.
              >Lew promply suggested to Nick that he take his idea and get out of Dodge.
              >Marco now has suggested something similar but more exotic. The Mazapil
              >Meteroite narrative offers an insight, "At once the corral was covered with
              >a phosphoescent light, while suspended in the air were small luminous
              >sparks as though from a rocket." And, "I saw this luminous air disappear,
              >and there remained on the ground only such a light as is made when a match
              >is rubbed." Something was going on, maybe it was the detected 0.3%
              >phosphorus burning once it was ignited.

              > Dave English
              >
              It was metallic dust or a porous solid made up of very poorly consolidated
              metal powder. Elemental phosphorus would I suppose be at least a possibility
              too if the meteorite material had conslidated at a relatively low
              temperature so that the phosphorus had not reacted with other materials.
              Migration of phosphorus vapour during cooling and heating cycles(eg during
              an eccentric solar orbit) could also lead to local concentrations of solid
              phosphrous.
              A neat idea David but as you say we need to await some more science.
              Nick
              Nick Martin, Bonnyton House, By Ayr, Ayrshire KA6 7EW ,Scotland, UK.
              Latitude 55 24'56" Longitude 4 26' 00".


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