PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Marco Polo Sample Analysis
An overview & priorities
Ian Franchi
Planetary & Space Sciences Research Institute
The Open University, Milton Keynes, MK7 6AA, UK
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Sample Science
•  Pre‐solar
events
and
processes
–  e.g.
nature
of
stellar
condensate
grains
and
ISM
organics
•  AccreCon
disk
processes
and
environment
–  e.g.
Cmescales
of
key
phases,
gas‐dust
interacCon
–
where/when/how
•  Asteroid
formaCon
and
evoluCon
–  e.g.
accreCon
history,
alteraCon
processes,
impact
events,
regolith
6th June 2008
Marco Polo Workshop, Cannes
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Early Solar System Science
•  Pre‐solar
grains
Nguyen
&
Zinner
2004
–  populaCons
not
found
in
meteorites?
•  AccreCon
disk
components
–  recording
earliest
stages
of
Solar
System
•  Requires
the
most
primiCve
materials
available
–  Least
modified
by
asteroidal
formaCon
processes
–  RelaCvely
insensiCve
to
space
weathering
•  Sample
size
requirements
small
(if
prisCne?)
–  Processes
reflected
in
large
variaCons
•  Requires
–
many
grains
from
mixed
regolith
–  Increased
probability
of
most
primiCve
materials
–  Grain
size?
‐
≥
100
microns
to
mms
6th
June
2008
Marco
Polo
Workshop,
Cannes
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Organics in Asteroidal Materials
•  Discrete
organic
phases
–
formaCon?
–  Survivors
of
asteroidal
processes?
What
didn’t
survive?
–  Products
of
asteroidal
processes?
Precursors?
Garvie
and
Buseck
2004
•  FormaCon
process(es)
of
amino
acids
•  Origin
of
enantomeric
excesses?
–  Parent
body
–
Strecker‐synthesis?
–  CPL
irradiaCon
during
formaCon?
•  Isotope
analysis
=
gram(s)
samples
•  Range
in
alteraCon
–  Require
mulCple
gram(s)
sized
parCcles
6th
June
2008
Marco
Polo
Workshop,
Cannes
Pizzarello
et
al
2006
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Organics - Thermal Effects
•  Thermal
maturaCon
of
organic
material
–  Macromolecule
modified
by
metamorphism
•  MaturaCon
of
kerogen
well
studied
–  Oil
generaCon
starts
≈370K
•  Surface
heaCng
major
concern
–  Life
Cme
of
NEO
≈
oil
formaCon
•  Ideally
target
not
significantly
heated
Tagish
Lake
Globules
–  How
constrained
orbit
evoluCon?
•  Larger
surface
parCcles
offer
lille
protecCon
–  How
gardened
are
micro‐g
regoliths
–  uniform
processing
with
depth?
6th
June
2008
Marco
Polo
Workshop,
Cannes
Nakamura‐Messenger
et
al
2006
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Organic Chemistry – Space Weathering
•  Astrobiological
significance
–  contaminaCon
control
required
at
all
stages
•  Materials
sensiCve
to
space
weathering
–  Degraded
by
UV,
solar
wind,
cosmogenic
nuclide
irradiaCon
&
micrometeorite
impact
–  SensiCve
to
mild
thermal
processing
•  Return
samples
“away”
from
the
surface
–  Any
depth
variaCon
in
a
gardened
regolith?
–  Larger
parCcles
(few
cm)
–
interior
protected
from
worst
exposure,
larger
aliquots
for
isotope
analyses 6th
June
2008
Marco
Polo
Workshop,
Cannes
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Asteroid Science – Surface Properties
•  Effects
of
space
weathering:
253 Mathilde = circles
–  Micrometeorite
impact
–  UV,
solar
wind
and
cosmogenic
irradiaCon
–  Thermal
processing
•  Links
remote
observaCon
with
the
detailed
knowledge
from
meteorites
•  Requires
a
representaCve
surface
sample
–  Components
or
samples
with
variable
exposure
to
invesCgate
processes
•  Regolith
formaCon
processes
–  Impact
processes,
solar
wind
composiCon,
etc
6th
June
2008
Marco
Polo
Workshop,
Cannes
Binzel et al 1996
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Asteroid Science – Alteration History
Grossman
et
al
2000
•  Thermal
heaCng
of
interior
during
formaCon
–  Heat
sources,
chronology,
cooling
rates,
etc.
•  Aqueous
alteraCon
–
effects
of
fluid
–  Water‐rock
interacCon
–
Cming,
temperature,
etc
–  Source
or
water
and
other
volaCles
–  Mobility
of
fluids
and
redistribuCon
of
material
•  Can
require
macro‐specimens
–  Textural
relaConship
of
components
–  e.g.
veins,
chemical
equilibraCon,
etc
•  Requires
large
samples
–
≥
mms
–  Range
of
degree
of
alteraCon
6th
June
2008
Marco
Polo
Workshop,
Cannes
Young
et
al
1999
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Samples – Contrasting Requirements
•  Early
&
pre‐solar
system
‐
prisiCne
primiCve
material
–  Free
from
the
effects
of
asteroidal
processes/water
(D
type
asteroid?)
•  Asteroid
formaCon
&
history
‐
range
of
processed
material
–  Showing
the
effects
of
asteroid
processes
•  Organics
–
prisCne
to
processed
–
but
minimal
surface
effects
(D
type?)
•  Meteorite‐asteroid
link
–
representaCve
space
weathered
material
•  Can
this
range
of
sample
types
be
found
on
a
single
asteroid?
–  Impact
processing
of
surface?
DisrupCon
&
re‐assembly?
–  MulCple
sample
sites
=
ability
to
exploit
any
surface
variaCon
•  Aim
for
regolith
of
a
primiCve
target
–
processed
material
also
present
Bland
et
al
Croat
et
al
2003
6th
June
2008
Marco
Polo
Workshop,
Cannes
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Collection from Regolith
•  Single
rock
sample?
Might
bring
back
a
meteorite.
•  Regolith
offers
best
opportunity
to
sample
wide
range
of
rocks
–  Regolith
heavily
processed?
Mix
of
materials
from
near
surface?
–  Most
prisitne
material
diluted
in
range
of
components
•  Need
to
collect
sample
material
protected
from
solar
wind
–  ParCcle
size
at
least
10s
microns
–
ideally
much
larger
•  Ideally
minimise
thermal
processing
–  Sub‐surface?
–
but
limited
variaCon
in
a
gardened
regolith
•  Maximise
sample
size
to
improve
probability
of
best
sample
•  Ideal
sample
–
large,
cored
sample
–  If
gardened
regolith
–
increase
odds
of
good
sample
–  If
regolith
not
gardened
–
sample
from
depth
6th
June
2008
Marco
Polo
Workshop,
Cannes
PLANETARY
AND
SPACE
SCIENCES
RESEARCH
INSTITUTE
Sample Requirement Summary
Science
area
Par*cle
size
Primi*ve‐ness
Pre‐solar
≥100s
microns
Most
prisCne
AccreCon
disk
≥100s
microns
Most
prisCne
Organics
cms
PrisCne
(to
altered)
Spectral
classificaCon
<micron
to
cms
RepresentaCve
of
surface
Asteroid
modificaCon
≥mms
Range
of
alteraCon
•  Smaller
samples
–
not
a
major
driver
on
total
mass
•  Organics
–
key
driver
on
mass:
≈2cm
parCcles
≈6
gram
each
•  Require
prisCne
material
or
range
of
alteraCon
–
mulCple
large
parCcles
•  Requires
10s
(ideally
100s)
grams
collected
–
cored?
•  Can
we
derive
constraint
from
thermal/orbit
model
and
regolith
turnover?
•  Need
to
be
able
to
select
areas
with
known
parCcle
size
6th
June
2008
Marco
Polo
Workshop,
Cannes