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  • 1
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    A comparison of Halley dust with meteorites, interplanetary dust and interstellar grains (1988)
    In:  CASI
    Details
    Publication Date: 2013-08-31
    Description: The variability of the mineral forming elements in the submicron Halley grains provides a powerful basis for comparison of Halley with the different classes of meteoritic materials that have been studied in the lab. The degree of variability in the Halley samples is larger than that seen in chondrites implying that Halley is more heterogeneous at the submicron scale. A critical distinction is that Halley contains abundant pure Mg silicates at the size scale while the carbon rich meteorites do not. The submicron dispersion composition seen in Halley is dramatically different from the narrowly constrained compositions seen in CI and CM (type 1 and 2) carbonaceous chondrites. These meteorites are carbon rich but are dominated by a hydrated silicate with a very narrow range of Mg/Si ratio. The Halley results are also unlike the composition variations seen in most of interplanetary dust types that are dominated by hydrated materials. The only known class of meteoritic material that appear to closely resemble the Halley data is a class of cosmic dust composed entirely of anhydrous minerals. The composition implies that Halley is dominated by olivine, pyroxene, iron sulfide, glass and amorphous carbonaceous matter.
    Keywords: ASTRONOMY
    Type: NASA, Washington, Infrared Observations of Comets Halley and Wilson and Properties of the Grains; p 66-67
    Format: application/pdf
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    NASA TECHNICAL REPORTS
  • 2
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    An Atlas of extraterrestrial particles collected with NASA U-2 aircraft, 1974 - 1976 (1976)
    In:  CASI
    Details
    Publication Date: 2019-06-27
    Description: Extraterrestrial particles collected during U-2 flights in the stratosphere were divided into four groups: chondritic, iron-sulfur--nickel, mafic silicates, and others. The chondritic aggregates are typically composed of Fe, Mg, Si, C, S, Ca, and Ni. Detectable levels of He-4 implanted from the solar wind occur in some. Olivine, spinel, and possibly pyrrhotite and a hydrated layered-lattice silicate were identified. The chondritic ablation particles contain no sulfur and appear to have been melted. Magnetite, olivine, and pyroxene were identified. The iron-sulfur-nickel type particles resemble meteoritic iron sulfide with a small amount of nickel, and contain magnetite and troilite. The mafic silicate type particles are iron magnesium silicate grains with clumps of chondritic aggregate particles adhering to their surfaces. Olivine and possibly pyrrhotite and pyroxene were identified. Most of the iron-nickel type particles are spherules and include taenite and wustite. The other type particles include nickel-iron mounds on spheroidal glassy-like grains having chondritic-like elemental abundances.
    Keywords: ASTRONOMY
    Type: NASA-TM-X-73152 , A-6672
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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