What is the Meaning of This?
What is the Meaning of This?
Claudia Alexander
Over a decade of exploration...
Discovery of an ocean: Priceless
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Major Findings:
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Project Inception—November 19, 1977
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Launch
h and
d IInterplanetary
t l
t
C
Cruise—Oct.
i
O t 18,
18 1989 - Dec.
D
5
5, 1995
Galileo Prime Mission—Dec. 5, 1995 - Dec. 15, 1997
Galileo Europa Mission (GEM)—Dec. 15, 1997 - Jan. 1, 2000
Galileo Millennium Mission (GMM)—Jan. 1, 2000 - Sept. 21, 2003
10/21/03
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Galileo End of Mission Summary
An ocean under the surface of Europa.
First ever successful probe of a gas giant atmosphere.
y
p
g
g
An icy satellite capable of generating its own magnetosphere (Ganymede).
Characterization of the thin exospheres of icy satellites.
Sufficient detail of Io’s volcanism to call it a window into Earth’s past.
Detailed sampling of the Io plasma environment and its intricate connection to the dynamics of the magnetosphere.
Complete understanding of the formation of the Jovian ring.
High resolution sampling of a rarely visited region: the Jovian radiation belts
Discovery of an asteroid with its own moon
‐cja‐ 2
Claudia with GLL
Comet Nevski‐Novichonok
(ISON) as it may appear at sunset on Nov 29 if it
sunset on Nov. 29, if it survives its close approach.
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Target of Rosetta Mission: Comet 67P/Churymov‐Gerasimenko.
Art Chmielewski’d best joke:
Ukrainian sources reported today that the Rosetta target comet Churyumov‐Gerasimenko
discoverer Dr. Churyumov married his former graduate student Dr. Gerasimenko. Dr. Gerasimenko will now hyphenate her name, Gerasimenko‐Churyumov. Dr. Churyumov stated that he would like the comet’s name to reflect his h h
ld lik h
’
fl hi
complete Russian name including the otchestvo, father’s name – Chury, making the comet’s name Churyvich‐Churyumov‐Gerasimenko‐Churyumov.
The matters became somewhat more complicated as Dr. Churyumov’s ex‐wife Natasha Harasimenko‐Churyumov stated via her attorney th t h
that her name needs to be added to 50% of her d t b dd d t 50% f h
ex‐husband’s discoveries. Consequently, from now on the comet’s name will be legally changed to Churyvich‐Churyumov‐Gerasimienko‐
Churyumov‐Harasimenko‐Churyumov.
What might have been a difficult linguistic problem was solved by the NEXT mission which was approved for an extension. df
t i
Th N t NEXT
The Next‐NEXT will now retrieve the impactor from Tempel 1 and use it to hit Churyvich‐Churyumov‐
Gerasimienko‐Churyumov‐Harasimenko‐
Churyumov. “Our calculations show that the impactor will split the C‐C‐G‐C‐H‐C into 6 equal chunks, one for each part of the name,” said the Next‐NEXT project manager
Next‐NEXT project manager.
Solar System Formation
interstellar cloud
4.6 Billion years ago ‐‐
solar nebula
& proto‐sun
Key Questions:
1.
Whether interstellar ices survived
the accretion shock and were
directly incorporated into comets?
2.
Whether any chem. rxn were
important in the part of the accretion
disk in which comets formed?
3.
Whether or not the details of the
abundances of ice in comets are
good constraints on the solar
system?
painting by Kazuaki Iwasaki
flattens into a
into a rotating disk
dust +gas dust
+gas
sticks to form planets, asteroids
& comets
HOT
COLD
early solar nebula
FROST LINE
FROST LINE
young sun
rocky bodies
rock‐ice bodies
comets
Comets = Frozen Time Capsules
Key Questions with which to unravel some of these mysteries to be addressed by
mysteries to be addressed by Rosetta
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D/H ratio
17O
Amorphous/crystalline ice
Homogeneity/inhomogeneity of the surface
New solar system H2O
δ17O
Along this line, geochemistry – the relationship with rocks determines the variation
within the solar disc
Prior H2O
Along this line, mass
Determines variation
within the solar disc
The Sun (Genesis)
δ18O
Modern Era of Comet Science
Modern Era of Comet Science
Lyttleton’’s Model
Lyttleton
s Model
Sandbank Model
– Swarm of ice and dust particles
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– Based on limited observations
• Meteor shower distributions
• Eclipsing the sun
Eclipsing the sun‐‐ no shadow
Whipple’
Whipple
’s model
s model
Icy Conglomerate Model
– Consist mostly of ice with sublimating layers
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– Based on indirect observation
– Non
Non‐‐gravitational forces
– Meteor storm ejection speeds and angles
speeds and angles
After Halley Comet 1986
After Halley Comet 1986
• Confirmed solid body ….R.I.P Sandbank Model
• But…
– Low AlbedoÆ darker than soot, no ice
,
– Low Bulk densityÆ
porous??
– JetsÆ
J t Æ not uniform t if
sublimation
– Not spherical‐‐> irregular shape body
Halley s comet taken by Giotto spacecraft on Halley’s
comet taken by Giotto spacecraft on
March 13th, 1986. Solid nucleus was confirmed.
Model Adaptations
Rubble Pile Model
• Fragments
F
t are more
tightly packed, and
welded together by
collision-induced
evaporation and
subsequent freezing of
ice.
• Shoemaker-Levy
S
event
supports model : tensile
strength
Fluffy Aggregate Model
Icy Glue Model
• Small
S ll particles
ti l weakly
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bound to each other,
forming a porous, open
structure with large
g
internal void spaces
•Shoemaker-Levy event
supports model : strength
• consist
i t off large
l
b
boulders
ld
fasten by icy dust grain
mix called the Whipple
glue
g
• Could explain the jets
found on Halley
•Failed to support the
Shoemaker Levy event
•No such reservoir of
boulders exist as of now
Data Results ‐ Inhomogeneities ?
T
Tempel 1
l1
Wild 2
Wild 2
≠
≠
•Smooth surface areas, craters, layered
•Several mini‐outbursts
•High porosity and low density‐
loose aggregates?
‐>> loose aggregates?
•Particle size = 1‐10 μm vs. 10 ‐
100 μm pre‐impact
•Homogenous albedo
• Sunlit surface T above sublimation T
•Similar to solar and CI chondritic material (A&C)
B ll
Borelly
•More Spherical
•Bowling Pin shaped
•Steep slopes, overhang, preserved craters
•Pre‐solar grains
•Brighter smooth terrain in the middle, rugged ends, mottled terrain
•Jets, outgassing‐‐> disintegrating
•Prominent collimated and fan ( like Halley) jets
•Large cohesive strength: icy dirt ball
•Hot dry surface
•Low albedo w/ bright spots
• No craters‐ weak surface?
• Crystalline silicate and other high T materials???
•Low albedo w/ bright spots
Comets from Afar:
Shoemaker-Levy 9 (SL9)
SL9 broke into pieces
during a close encounter
with Jupiter in 1992 and
collided with Jupiter
p
in
July 1994.
Impacts by disrupted
objects can make crater
chains like this one on
Ganymede
New Issues: Do we have comet ‘geology’ such as
cryo-volcanism
y
or p
planation?
DI: Ve
everka et al (2012)
Stardust-NExT: Veverka et al (2012)
DI: Belton & Melosh (2009)
2/6/2012
US Rosetta Experimenter Workshop,
Dana Point, CA
14
1965 Caltech Black Student Union
Claudia Alexander graduation from UCLA: 1985
from UCLA: 1985
Windows to Adventure!
Will be adding Rheasilvia
into Book 1 (Mountains)
Where to find me today! (May, 2013)
1.
2.
Astronomy Wise
Pasadena Now
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3.
Literary Network for the Baltimore Urban Book Festival
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4.
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Thelitearynetwork.com/2013/
Thelitearynetwork
com/2013/
04/30/claudia‐alexander‐
interview‐baltimore‐urban‐
bookfestival‐featured‐author
African‐American Author Expo
Amazon Author Page
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pasadenanow.com/main/red‐
phoenix‐rising‐at‐litfest
Amazon.com/clauda‐
alexander/e/B008GN871M
And catch me in June at the Liemert Park Village Book Festival
Sources of Inspiration
Sources of Inspiration
• Ray T. Reynolds & Pat Cassen (Ames Research) –
Jupiter Orbiter Probe (Io volcanic paper)
• Yvonne Pendleton (Ames Research/NASA HQ) having a family will cause a hit on your career, but its OK!
family will cause a hit on your career, but its OK!
• CTR – Published & Published but Perished just the Same! (cartoon on his office wall! – interested in just about everything)
about everything)
• TIG – a vision about comet exploration & the future of finite differencing methods • Chris Jones (JPL – how to manage)
• Roberta Johnson (UCLA, UM, UCAR – it’s OK to do both education and science!)
education and science!)
Total Solar Eclipse (France, 2000?)
[ h
[Chris was there!]
h
]
Ray
F kC
Frank C.
Krishan
Linda S.