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Titel |
Development of analytical theory of the physical libration for a two-layer Moon |
VerfasserIn |
Natalia Petrova, Yurii Barkin, Alexander Gusev, Tamara Ivanova |
Konferenz |
EGU General Assembly 2010
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Medientyp |
Artikel
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Sprache |
Englisch
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Digitales Dokument |
PDF |
Erschienen |
In: GRA - Volume 12 (2010) |
Datensatznummer |
250042737
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Zusammenfassung |
Investigation is being carried out in the frame of Russian-Japanese grant and directed onto
providing of the future observations in the frame of the ILOM-project which is planned
onto the end of the second decade. The analytical theory presents both scientific
interest in its own right and can be useful as a base for the lunar annual in a future,
as a clue to lunar interiors and to processes inside the lunar body. A comparison
of the libration’s analytical theory with new observations will allow to refine the
parameters of lunar interiors: an existence or absence of a core, its size, composition
and state of aggregation, Love numbers, qualitative parameter Q, etc. Contrary to
the usual application of numerical libration models for analyses of observations,
the analytical model is able to predict the new harmonics, early unknown and not
observed (owing to the insufficient accuracy of observations) in libration’s series of
observations.
As part of the investigation the following results were achieved.
Development of the analytical theory of the Lunar Physical Libration (LPhL) were
performed using the Poisson Series Processor (PSP). The base solution is realized for the
“main problem” of the LPhL in view of 4-th harmonic of selenopotential. Data on a
dynamical figure of the Moon are incorporated in the theory on the basis of new observations
of the Lunar gravitational field, received in a frame of space projects Clementine (1994,
NASA), Lunar Prospector (1999, NASA) and the SELENE (2007 – 2009, Japan). On the
basis of the constructed theory the following actions were done: 1) analyses of the present
dynamical models; 2) modeling of stars trajectories in the field of view of the future optical
telescope, which is planned to be placed on one of the Lunar poles in the second stage of the
Japanese project SELENE-B - ILOM. Results of modeling have shown opportunities of
determination of LPhL-parameters with the desirable accuracy 0.001 arc seconds
planned in the ILOM-project. Prognosis recommendations are made for the future
experiment.
The model of free rotation of the two-layer Moon is constructed, the periods of the free
modes and of the librational motion of a pole are received, effects of influence of a
lunar core on behavior of LPhL-harmonics caused by the solid-state rotation of
the Moon are deduced. Computer simulating has revealed the sensitivity of the
free libration periods to core’s ellipticity and to core-mantle boundary dissipation
parameters. Geometrical interpretation of the pole motion owing to the free libration is
given.
For the first time the theoretical model of tidal potential of the Moon is developed, on the
basis of the model the analytical formulae for variations of the Stockes coefficients of the
2-nd order and of the speed of the Lunar rotation is received in dependence on
time.
For a two-layer structure of the Moon and the Mercury Cassini’s law were stated at the
first time: 1. a two-layer Moon keeps its own stationary rotation; 2. there is a splitting
of Cassini nodes and angular momentums of Lunar mantle and core; 3. the same
phenomenon will be observed for any two-layer planet (Mercury); 4. the differential
rotation of a core and mantle is inherent to a planet as result of a generalized Cassini’s
Laws.
Theoretical and practical methods of construction of the theory of rotation of the Earth
have been successfully applied in the development of the theory of rotation of the Moon, in |
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