Transcript ppt - Institute for Astronomy

Astrobiology 740
Stardust Highlights from LPSC
March 17, 2006
Dr. Karen J. Meech, Astronomer
Institute for Astronomy, Univ. Hawaii
[email protected]; (808) 956-6828
Return To Earth
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Jan 15, 2006
Image from DC-8 flying N
of the Nevada drop site
Soft landing at 3:10am
MST
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Landed in mud, not water
Some of the ablation
material came off at impact,
leaving a “clean” capsule
Capsule was intact
Sample
Recovery
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Only Comet samples looked at, no ISM samples
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Each compartment is removed (surrounded by a thin foil)
Aerogel is cut into wedges for particle extraction
Particles visible to the naked eye
Cratering analysis of the very small dust in the foils
Analysis goes through 7/15/06
Mineralogy & Petrology
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Crystalline amorphous silicates
are abundant
Some very large particles ~40 mm
Many grains are chondritic in
composition for most elements
C is heterogeneously distributed in
particles
Particles are very primitive
compared to IDPs
Large 1-10 micron grains of
forsterite, enstatite, pyrrhotite, and
perhaps CaI like minerals are
common
Chemistry
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Possible contaminants
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Layer of melted
aerogel on outside
with NiFeS grains
CaO > 0.5 wt %
FeO < 1 wt %
High Cr, low Fe
olivines
C is heterogeneously
distributed in grains
Weak organic signals
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Above: forsterite
grain
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Organics rich in oxygen (alcohols and ethers) and N (amines
and pyrols) – similar to IDPs
Isotopic signatures (raman)
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Many control studies
Aerogel ahs aromatic & aliphatic
functional groups
Higher D/H, 15N/14N: dD = 850
+/- 340 per mil
No evidence of carbonates or
clay minerals
Impact Craters
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Seen in the Al foils
Many crater 0.5-1.0 mm across
Cumulative size distribution
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Slope see in Al shallower than the dust flux monitor
from flyby
Mass index of 0.2 vs. 0.7 for DFM
Conclusions
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~ 200 particles > 10 mm
Craters show aggregates of particles
Impact residues have a variety of compositions
Conclusions
Crystalline & amorphous silicates are
abundant: uncertain how much is
preserved from ISM
 Many high temperature minerals are seen
 Clearly the cometary material has seen
high Temperatures
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Hot regions of solar nebula?
 X-wind heating in the disk?
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