4th

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4th
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The importance of Stardust

• The first primitive solar system samples from a
  known body
• The body is from the Kuiper Belt
• It formed at the extreme edge
• of the solar nebula disk

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Processing of solids in the solar nebula

• Comets

Asteroids
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The Importance of Sample Return Missions
Science is done on the ground Instrumentation
is state-of-the-art and more Ultimate in
precision sensitivity Not limited by mass,
power, cost or reliability Results can be
confirmed by several methods Instruments can be
calibrated Analysis is iterative not limited
by pre-conceived ideas Samples - a resource for
present and future study
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COLLECTING COMET DUST
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Aerogel
Least Dense Solid The solid substance with the
lowest density is aerogel, in which tiny spheres
of bonded silicon and oxygen atoms are joined
into long strands separated by pockets of air.
The latest and lightest versions of this
substance weigh just 3mg/cm3, and are produced by
the Jet Propulsion Laboratory in Pasadena,
California, USA.
Guiness Book of World Records 2003
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Aerogel Fabrication Process
Acetonitrile CH3CN Water H2O
Acetontrile CH3CN
Precursor Distillation, Reflux, Partial
Hydrolysis
Solvent Removal Critical Point Extraction
Gelation Polymerization
Final Hydrolysis Dilution
Aerogel
Ethyl Alcohol CH3CH2OH Tetraethyl Orthosilicate
(C2H5O)4Si Water H2O Nitric Acid HNO3
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Fred Horz JSC
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Polished section
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Hot glass on cold glass
gt1700 ºC
lt650 ºC
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Meteoroid in aerogel from Mir spacestation (FIB
section)
Graham et al 2005
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7 years - 3 loops around the Sun
Wild 2 orbit
Earth gravity Assist 1/15/2001
Earth return 1/15/2006
Loop 1
Loops 2 3
Launch 2/7/99
Interstellar dust Collection periods
Wild 2 encounter 1/2/2004
direction of interstellar flux
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Wild 2 - originally derived from the Kuiper
Belt formed gt10 times further from Sun than did
the asteroidal meteorites
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Wild 2 - Stardust
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Shoemaker Basin Wild 2s monument valley
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Bright spot Cold Spot? Condensed material?
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SampleReturnCapsule
Hypervelocity testing at NASA Ames Research Center
WORLD RECORD ENTRY SPEED!
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NHK TV Japan
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Track Profiles Stardust at Wild 2
Bowl
Hedgehog
Stylus
Ginseng
Cylinder
Carrot
Turnip
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Comet Wild 2 dust capture at 6.1 km/s
The biggest particles travel the furthest
lt fine-grained fraction gt
lt coarse grained fraction gt
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5µm - 10µm extra grains - terminal particle
already removed
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Rocks along a 2 mm track
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Track Morphology
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X-Ray Tomographic Profile of a Track
(Tomoki et al, Spring 8)
High-Res. Tomography
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Extracting Comet Dust keystones
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Cell 44, Track 4 Analysis
TP
Fe distribution along Track 4
P1
(Brennan et al., SSRL)
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Cometary forsterite Fo99

• 0.5 µm

Track 10 fragment Arinna-Faukland
Melted aerogel With Fe,Ni sulphide droplets
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Wild 2 forsterites
Unmelted aerogel

• Refractory
• CaO gt 0.5 wt
• Fe0 lt 1
• Hi Cr lo Fe (LICE)
• Hi Mn (LIME)
• probable
• Variable Fe

• Melted aerogel
• with FeNi sulfide beads

Forsterite
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1 µm FeS grain
HAADF
SE
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GEMS ? (Glass with Embedded Metal and Sulfides)
Interplanetary dust
Comet Wild 2
Interstellar amorphous silicates?
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Stardust sample 7-10-9c-(1-4) enstatite and
forsterite
forsterite

enstatite
glass with inclusions
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Vanadium Titanium Nitride
Track 25 (Inti-Easter) 12µm CAI-like
50 nm
Anorthite
Diopside
anorthite, spinel, diopside, Al,Ti diopside
more
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Inclusions in Stardust refractory particle -
track 25 Inti
Instrument 200 keV STEM with monochromator

Acquisition time 10 seconds
Titanium-L2,3 edges
25 nm
Vanadium-L2,3 edges
2 Å diameter nanoprobe positioned on upper
region of inclusion
Nitrogen-K edge
Dai, Bradley et al
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SiO2
Fa 99 (with 5MnO)
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Craters in the Al Foils
TEM section prepared using FIB
Typical 1 micron diameter crater preserved on the
foil surface.
Section attached to the TEM grid
Data from Teslich, Graham, Dai and Bradley (LLNL)
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Carbon coating
TEM-EDS mapping of the sample C2054W-crater-13
Data from Dai, Graham, Teslich and Bradley (LLNL)
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Graham et al
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Wild 2 Conclusions

• Essentially all impacts contain analyzable
  material ?
• Large (1-20µm) grains of forsterite, enstatite,
  pyrrhotite
• and perhaps CAI-like minerals appear to be
  common
• The comet is clearly unequilibrated - variable Fe
  in olivine,
• Cr rich forsterite, variable Ni in sulfides
• Wild 2 contains abundant high temperature
  minerals
• No hydrated silicates, carbonates, magnetite seen
  (yet)
• ? Greenberg model, C Chondrites, Temple 1 or IDPs
  (?)

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Dust Model - Griffith Observatory
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Hot minerals in the coldest placewhere did they
come from?

• Inner regions of the nebula?
• Products of annealing?
• Condensates?
• X wind?
• From other other stars?

Minor element and isotopic compositions (ie
Kevin!) will solve the mystery
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Origin of mineral grains in the Kuiper Belt?

• Pre-solar minerals
• Condensates from hot regions of the solar nebula
• Interstellar amorphous silicate annealed in hot
  inner regions of nebula
• reworked inner nebula solids-chondrules more
• fragments of large Kuiper belt comets that broke
  up
• Fragments of inner SS objects

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Mysteries of submicron cosmic silicates

• Interstellar - appear amorphous
• Circumstellar - partly crystalline
• Long period comets - contain xtls
• Short period comets - do not
• except for Tempel 1
• but only just after Deep Impact!

10µm silicate feature (sub-micron grains)

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Cometary impact crater preserved on the surface
of the Al foil
DC 1.74 mm
Impact residue lining the crater wall.