scholarly journals Polyaxial Figures of the Moon

2011 ◽  
Vol 1 (4) ◽  
pp. 348-354 ◽  
Author(s):  
H. İz ◽  
X. Ding ◽  
C. Dai ◽  
C. Shum
Keyword(s):  
Center Of Mass ◽  
The Moon ◽  
Shape Parameters ◽  
Axially Symmetric ◽  
Laser Altimetry ◽  
Additional Information ◽  
All Solutions ◽  
Ellipsoidal Model ◽  
Lunar Topography ◽  
Topography Model

Polyaxial Figures of the MoonThis study investigates various models to represent the gross geometric shape of the Moon. Asymmetric polyaxial geometric models-namely three-, four- and six-axial lunar figure - are compared and contrasted with the axially symmetric three-axis ellipsoidal model derived from Chang'e 1 and SELENE laser altimetry data. All solutions confirm a hydrostatically stable lunar shape shifted with respect to the lunar center of mass by topography. Model solutions with increasing complexity offer additional information about the regional properties of the lunar topography. Solution statistics suggest that axially symmetric lunar figures and their center of figure parameters can be replaced by an equivalent asymmetric lunar shape centered at the center of mass of the Moon. Thus, using only three shape parameters, one can derive an "egg" shape that better accommodates the true geometry of the Moon.

scholarly journals Polyaxial figures of the Moon from the lunar reconnaissance orbiter laser altimetry and multi-mission synthesis of the lunar shape

2012 ◽  
Vol 2 (2) ◽  
pp. 107-112
Author(s):  
H. Iz ◽  
C. Shum ◽  
C. Dai
Keyword(s):  
Center Of Mass ◽  
Geometric Shape ◽  
Model Parameters ◽  
The Moon ◽  
Altimetry Data ◽  
Laser Altimetry ◽  
All Solutions ◽  
Lunar Reconnaissance Orbiter ◽  
Combined Solution

Polyaxial figures of the Moon from the lunar reconnaissance orbiter laser altimetry and multi-mission synthesis of the lunar shapeLast decade witnessed a plethora of missions to the Moon by China (Chang'E-1 and Chang-E-2), Japan (SELenological and ENgineering Explorer, SELENE), India (Chandrayaan-1) and USA (Lunar Reconnaissance Orbiter), all carried out laser altimetry measurements. This study is a follow up to a series of earlier investigations that produced a number of new models to represent the gross geometric shape of the Moon using Unified Lunar Control 2005, Chang'E-1, and SELENE laser altimetry data using the Lunar Reconnaissance Orbiter laser altimetry measurements. The symmetric and asymmetric polyaxial geometric models derived from Lunar Reconnaissance Orbiter laser altimetry data, namely, three, four and six-axial lunar figure parameters, are compared and contrasted with the corresponding model parameters estimated from the Chang'E-1 and SELENE laser altimetry. All solutions produced geometric shape, orientation parameters, and the parameters of the geometric center of lunar figure with respect to the center of mass of the Moon showing remarkable agreement with each other within 100 m. A combined solution by the fusion of uniformly sampled laser altimetry data from all three missions produced the best estimates for the lunar shape, orientation, and lunar center of figure parameters, and their realistic error estimates.

scholarly journals Mass and spin for classical strings in dS3

2021 ◽  
Vol 2021 (5) ◽  
Author(s):  
Klaas Parmentier
Keyword(s):  
Black Hole ◽  
Evolution Equation ◽  
Cosmic Strings ◽  
Center Of Mass ◽  
Open String ◽  
Conserved Quantities ◽  
Numerical Example ◽  
All Solutions

Abstract We demonstrate that all rigidly rotating strings with center of mass at the origin of the dS3 static patch satisfy the Higuchi bound. This extends the observation of Noumi et al. for the open GKP-like string to all solutions of the Larsen-Sanchez class. We argue that strings violating the bound end up expanding towards the horizon and provide a numerical example. Adding point masses to the open string only increases the mass/spin ratio. For segmented strings, we write the conserved quantities, invariant under Gubser’s algebraic evolution equation, in terms of discrete lightcone coordinates describing kink collisions. Randomly generated strings are found to have a tendency to escape through the horizon that is mostly determined by their energy. For rapidly rotating segmented strings with mass/spin < 1, the kink collisions eventually become causally disconnected. Finally we consider the scenario of cosmic strings captured by a black hole in dS and find that horizon friction can make the strings longer.

scholarly journals Editorial for Special Issue “Advances in Satellite Altimetry and Its Application”

2019 ◽  
Vol 11 (24) ◽  
pp. 2913
Author(s):  
Denise Dettmering ◽  
Marcello Passaro ◽  
Alexander Braun
Keyword(s):  
Sea Ice ◽  
Satellite Altimetry ◽  
Method Development ◽  
Review Paper ◽  
The Moon ◽  
Special Issue ◽  
Laser Altimetry ◽  
Coastal Regions ◽  
Research Papers ◽  
Earth Systems

This special issue compiles studies from different disciplines presenting recent advances in the field of radar and laser altimetry including new and future altimetry missions and their applications. It comprises eight research papers as well as one review paper, and covers method development as well as applications, which target diverse Earth systems (oceans, coastal regions, sea-ice, inland) as well as the Moon.

scholarly journals The Influence of Heterogeneity on Lunar Irradiance Based on Multiscale Analysis

2019 ◽  
Vol 11 (22) ◽  
pp. 2696
Author(s):  
Xiangzhao Zeng ◽  
Chuanrong Li
Keyword(s):  
Correction Factor ◽  
Lunar Surface ◽  
Multiscale Analysis ◽  
Radiometric Calibration ◽  
The Moon ◽  
Model Data ◽  
Lunar Topography ◽  
Satellite Sensors ◽  
Observation Geometry ◽  
The Impact

The Moon is a stable light source for the radiometric calibration of satellite sensors. It acts as a diffuse panel that reflects sunlight in all directions, however, the lunar surface is heterogeneous due to its topography and different mineral content and chemical composition at different locations, resulting in different optical properties. In order to perform radiometric calibration using the Moon, a lunar irradiance model using different observation geometry is required. Currently, two lunar irradiance models exist, namely, the Robotic Lunar Observatory (ROLO) and the Miller and Turner 2009 (MT2009). The ROLO lunar irradiance model is widely used as the radiometric standard for on-orbit sensors. The MT2009 lunar irradiance model is popular for remote sensing at night, however, the original version of the MT2009 lunar irradiance model takes less consideration of the heterogeneous lunar surface and lunar topography. Since the heterogeneity embedded in the lunar surface is the key to the improvement of the lunar irradiance model, this study analyzes the influence of the heterogeneous surface on the irradiance of moonlight based on model data at different scales. A heterogeneous correction factor is defined to describe the impact of the heterogeneous lunar surface on lunar irradiance. On the basis of the analysis, the following conclusions can be made. First, the influence of heterogeneity in the waning hemisphere is greater than that in waxing hemisphere under all 32 wavelengths of the ROLO filters. Second, the influence of heterogeneity embedded in the lunar surface exerts less impact on lunar irradiance at lower resolution. Third, the heterogeneous correction factor is scale independent. Finally, the lunar irradiance uncertainty introduced by topography is very small and decreases as the resolution of model data decreases due to the loss of topographic information.

scholarly journals The mean distance to the Moon as determined by radar

1965 ◽  
Vol 21 ◽  
pp. 81-93 ◽  
Author(s):  
B. S. Yaplee ◽  
S. H. Knowles ◽  
A. Shapiro ◽  
K. J. Craig ◽  
D. Brouwer
Keyword(s):  
The Moon ◽  
The Earth ◽  
Lunar Topography ◽  
Radar Measurements ◽  
The Mean

The results of 1959-1960 radar measurements of the distance of the Moon are given. The method of reduction of the data is described The possible effects of lunar topography and errors of other origins are discussed, as well as the effects of different constants such as the radii of the Earth and of the Moon.

scholarly journals High-energy collision of particles in the magnetic field far from black holes

2014 ◽  
Vol 29 (29) ◽  
pp. 1450151
Author(s):  
O. B. Zaslavskii
Keyword(s):  
Magnetic Field ◽  
Black Hole ◽  
Center Of Mass ◽  
High Energy ◽  
Axially Symmetric ◽  
High Energy Collision ◽  
Mass Frame ◽  
Symmetric Black Hole ◽  
Rotating Star ◽  
The Magnetic Field

We consider collision of two particles in the axially symmetric black hole metric in the magnetic field. If the value of the angular momentum |L| of one particles grows unbound (but its Killing energy remains fixed) one can achieve unbound energy in the center-of-mass frame E c.m. In the absence of the magnetic field, collision of this kind is known to happen in the ergoregion. However, if the magnetic field strength B is also large, with the ratio |L|/B being finite, large E c.m. can be achieved even far from a black hole, in the almost flat region. Such an effect also occurs in the metric of a rotating star.

Comment on the center‐of‐mass offset of the moon

1978 ◽  
Vol 46 (7) ◽  
pp. 762-762
Author(s):  
Allan Walstad
Keyword(s):  
Center Of Mass ◽  
The Moon
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