Transcript Ice Across the Solar System - Lunar and Planetary Institute

Ice At the Moon - How the
Moon Mineralogy Mapper on
Chandrayaan-1 Will Help
Noah E. Petro
NASA Goddard Space Flight
Center
March 4th, 2009
A Bit About Me
• Grew up in southern New York state
• Became interested in Geology as a
student at the Fox Lane High School
• Earned a degree in geology and
education from Bates College (2001)
• PhD from Brown University in 2006
• Post Doctoral researcher at NASA
Goddard
Clementine
Albedo
Topography
Lunar Prospector
FeO
Th
Color
Polar
H
The Moon’s Orientation
1.54º tilt to
the ecliptic
Kaguya View of
Shackleton/South Pole
Earth Based Radar View of the
South Pole
Lunar South Pole
The search for water …
Ice on the Moon
Moon’s inclination to the Sun is only 1.5°, allowing permanently shadowed regions inside
craters
Lunar Prospector Neutron Spectrometer looks for
"slow" (or thermal) and "intermediate" (or
epithermal) neutrons which result from collisions of
normal "fast" neutrons with hydrogen atoms. The
ice was thought to be spread over 10,000 to 50,000
square km and amount to 6 billion metric tons. A
significant amount of hydrogen would indicate the
existence of water - 4.6% over the north polar
region and 3% over the south, at a depth of about 40
centimeters beneath dry regolith.
1) Fluxes of fast and epithermal neutrons from Lunar Prospector:
Evidence for water ice at the lunar poles, Feldman et al., Science, v. 281, p. 1496, 1998
No water (as OH-) was detected from the July 31, 1999 crash of Lunar
Prospector into the Moon.Possible reasons: might have missed the target
area; might have hit a rock; crash had too little energy to separate water
from minerals; plume hidden from telescopes by crater walls; telescopes
mispointed; or hydrogen simply may not be in the form of water ice.
Lunar South Pole
The search for water …
Lunar Prospector data
Map of Hydrogen
(red = greater
abundance of H)
Lunar South Pole
The search for water …
View into Shackleton Crater
View into Shackleton Crater
Polar cold traps
• Scientists use the Kelvin absolute
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temperature scale, where ice melts at
273.16 K.
Dry ice forms at Mars atmospheric pressure
at 145 K, water ice clouds form at ~180-200
K.
Liquid oxygen (1 bar): 90 K
Liquid nitrogen (1 bar): 77 K
Temperatures in Shackleton Crater: 88-86 K
No surface
ices
exposed?
Mission Overview:
M3 on Chandrayaan-1
What We Know From Apollo
What We Learned
• Lunar samples are
all very dry
• Limited
compositional
variability relative to
the Earth
• Small amount of
water in volcanic
glasses
The Electromagnetic
Spectrum &Lunar Mineral
Signatures
Lunar Samples
0.7
Plagioclase
0.6
Reflectance
0.5
Olivine
0.4
Glass
0.3
0.2
Pyroxenes
0.1
Adsorbed
Water
Soils
0
1000
1500
2000
Wavelength nm
2500
3000
M3 Pushbroom Imaging Spectometer
Orbit Path
Continuous
261 Band
Spectrum
40 km Swath
62.3 m Sampling
M3 Pushbroom Imaging Spectometer
Orbit Path
Continuous
261 Band
Spectrum
40 km Swath
62.3 m Sampling
M3 as a mapping spectrometer
0.8
0.7
Reflectance
0.6
0.5
0.4
0.3
0.2
0.1
X
0
400
700
1000
1300
1600
1900
Wavelength (nm)
2200
2500
2800
View into Shackleton Crater
Lunar Mineral Signatures
Lunar Samples
0.7
Plagioclase
0.6
Reflectance
0.5
Olivine
0.4
Glass
0.3
0.2
Pyroxenes
0.1
Adsorbed
Water
Soils
0
1000
1500
2000
Wavelength nm
2500
3000
Lunar Reconnaissance
Orbiter / Chandrayaan-1
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Two most recent (late 2008-2009) spacecraft orbiting Moon
Powerful, modern radar experiments will image PSR’s in detail
Lyman-Alpha Mapping Project (LAMP) will see interiors of PSRs by
galactic far-ultraviolet light (hydrogen emissions)
Lunar Orbiter Laser Altimeter will measure albedo on 5-m footprint
scales, detecting 4% ice
Neutron spectrometer (LEND) will resolve hydrogen atoms
DIVINER will measure surface temperatures and rock environments
Lunar CRater Observation and
Sensing Satellite [LCROSS]
For more information…
• Lunar Photo of the Day
– http://lpod.wikispaces.com/
• Lunar and Planetary Institute Lunar Resources
– http://www.lpi.usra.edu/lunar/
• Apollo Surface Journal
– http://history.nasa.gov/alsj/