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| Titel |
Estimation of Comet 67P Surface Properties from CONSERT Data Obtained during Descent of Philae |
| VerfasserIn |
Dirk Plettemeier, Christoph Statz, Sebastian Hegler, Ronny Hahnel, Alain Herique, Wlodek Kofman |
| 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 |
250099746
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| Publikation (Nr.) |
 EGU/EGU2014-15563.pdf |
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| Zusammenfassung |
| The Comet Nucleus Sounding Experiment by Radiowave Transmission (CONSERT) is an
experiment aboard the ESA spacecraft "Rosetta". After a detailed observation of the
comet 67P/Churyumov–Gerasimenko, the landing unit "Philae" will descend to
the cometary nucleus in November 2014. The CONSERT instrument will then
perform a sounding of 67P’s core using radiowaves. From these data an estimation
of several properties of the comet 67P shall be derived. These include the mean
permittivity, the mean absorption and volume scattering of the comet nucleus, the
size of irregularities and/or small structures inside the comet, the size of potential
cometesimals forming the nucleus as well as the re?ection coef?cient at internal
interfaces.
In addition to the nominal operation, i.e. the bi-static sounding through the cometary
nucleus, the CONSERT instrument will operate during the descent of lander "Philae" where
the direct path between orbiter and lander as well as reflections from the surface of the
comet will be measured. From this data, scientific as well as operational information
can be derived. The direct path is determined by lander and orbiter positions and
attitudes.
In addition to theses properties the reflected path is influenced by the comet’s surface
permittivity distribution and roughness as well as by the stratigraphy close to the surface. The
data obtained during the descent will provide initial values for CONSERT’s main
objective.
In this presentation we will introduce a methodology to obtain the surface permittivity
distribution using a regularized least-squares approach and gradient based optimization as
well as performance estimates for the proposed algorithm depending on instrument
constraints, orbitography and surface roughness. |
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