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| Titel |
Revealing lunar crustal density stratification with GRAIL data |
| VerfasserIn |
Jonathan Besserer, Francis Nimmo, Mark A. Wieczorek, Renee C. Weber, Walter S. Kiefer, Patrick J. McGovern, David E. Smith, Maria T. Zuber |
| Konferenz |
EGU General Assembly 2014
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 16 (2014) |
| Datensatznummer |
250090385
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| Publikation (Nr.) |
 EGU/EGU2014-4619.pdf |
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| Zusammenfassung |
| The bulk density of the porous lunar crust has recently been mapped using high-resolution
gravity provided by the Gravity Recovery and Interior Laboratory (GRAIL) mission.
However, the vertical structure of the crust, which is key to understanding its thermal and
seismic characteristics, and its origin and subsequent modification, is currently poorly
known.
Here, we analyze GRAIL data using a localized, multitaper admittance approach to
determine the vertical density structure of the lunar crust. We used spherical harmonic
coefficients of the Moon’s gravity, topography, and topography-induced gravity fields up
to spherical harmonic degree - = 550. The gravity data were derived from the
GRAIL nominal and extended missions’ tracking data; the topography data were
derived from the principal axis referenced Lunar Orbiter Laser Altimeter (LOLA)
data.
We find that mare regions are characterized by a distinct decrease in density with
depth, while the farside is characterized by an increase in density with depth at
an average rate of ~30kgm-3km-1 and typical surface porosities of 20%.
Such high inferred surface porosity values are compatible with Apollo samples and
lunar meteorites. The Apollo 12 & 14 landing site region has a similar density
structure to the farside, permitting a comparison with seismic velocity profiles. The
South Pole-Aitken (SP-A) impact basin region appears distinct with a near-surface
low-density (porous) layer 2-3 times shallower than the rest of the farside. This result
suggests that redistribution of material during the large SP-A impact likely played a
major role in sculpting the lunar crust. Mapping the spatial distribution of shallow
porosity, as we have attempted here, will allow comparison with other data sets. |
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