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An ET Origin for Stratospheric Particles Collected during the 1998 Leonids Meteor ShowerOn 17 November 1998, a helium-filled weather balloon was launched into tfle strato- sphere, equipped with a xerogel microparticle collector. The three-hour flight was designed to sample the dust environment in the stratosphere during the Leonid meteor shower, and possibly to capture Leonid meteoroids. Environmental Scanning Election Microscope analyses of the returned collectors revealed the capture of a -30-pm particle. with a smooth, multigranular shape, and partially melted, translucent rims; similar to known Antarctic micrometeorites. Energy-dispersive X-ray Mass Spectroscopy shows en- riched concentrations of the non-volatile elements, Mg, Al, and Fe. The particle possesses a high magnesium to iron ratio of 2.96, similar to that observed in 1998 Leonids meteors (Borovicka, et al. 1999) and sharply higher than the ratio expected for typical material from the earth's crust. A statistical nearest-neighbor analysis of the abundance ratios Mg/Si, Al/Si, and Fe/Si demonstrates that the particle is most similar in composition to cosmic spherules captured during airplane flights throucrh the stratosphere. The mineralogical class is consistent with a stony (S) type of silicates. olivine [(Mg, Fe)2SiO4] and pyroxene [(Mg,Fe)SiO3]-or oxides, herecynite [(Fe,Mg) Al2O4]. Attribution to the debris stream of the Leonids' parent body, comet Tempel-Tuttle, would make it the first such material from beyond the orbit of Uranus positively identified on Earth.
Document ID
19990103946
Acquisition Source
Marshall Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Noever, David A.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Phillips, James A.
(Bishop WebWorks Bishop, CA United States)
Horack, John M.
(NASA Marshall Space Flight Center Huntsville, AL United States)
Jerman, Gregory
(NASA Marshall Space Flight Center Huntsville, AL United States)
Myszka, Ed
(CSC Corp. Huntsville, AL United States)
Date Acquired
August 19, 2013
Publication Date
January 1, 1999
Subject Category
Geophysics
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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