Coordinate Time On and Near the Earth

1985 ◽  
Vol 54 (3) ◽  
pp. 254-254 ◽  
Author(s):  
Neil Ashby ◽  
David W. Allan
Keyword(s):  
Coordinate Time ◽  
The Earth

scholarly journals Coordinate time in the vicinity of the Earth

1986 ◽  
Vol 114 ◽  
pp. 299-313 ◽  
Author(s):  
D. W. Allan ◽  
N. Ashby
Keyword(s):  
General Relativity ◽  
Atomic Clock ◽  
Space Vehicles ◽  
Atomic Clocks ◽  
Coordinate Time ◽  
The Earth ◽  
Frequency Comparison ◽  
New Applications ◽  
Frequency Metrology

Atomic clock accuracies continue to improve rapidly, requiring the inclusion of general relativity for unambiguous time and frequency clock comparisons. Atomic clocks are now placed on space vehicles and there are many new applications of time and frequency metrology. This paper addresses theoretical and practical limitations in the accuracy of atomic clock comparisons arising from relativity, and demonstrates that accuracies of time and frequency comparison can approach a few picoseconds and a few parts in 1016, respectively.

Coordinate Time On and Near the Earth

1984 ◽  
Vol 53 (19) ◽  
pp. 1858-1858 ◽  
Author(s):  
Neil Ashby ◽  
David W. Allan
Keyword(s):  
Coordinate Time ◽  
The Earth

The modification of the singular spectral analysis basic method for improving the accuracy of forecasting the irregularity of the Earth rotation

2020 ◽  
pp. 54-65
Author(s):  
Александр Кузьмич Гречкосеев ◽  
Александр Сергеевич Толстиков ◽  
Виктор Мартынович Тиссен ◽  
Виталий Сергеевич Карманов ◽  
Анна Игоревна Ваганова
Keyword(s):  
Spectral Analysis ◽  
Earth Rotation ◽  
Forecast Accuracy ◽  
Basic Method ◽  
Earth’S Rotation ◽  
Earth's Rotation ◽  
Coordinate Time ◽  
Singular Spectral Analysis ◽  
The Earth ◽  
Rotation Parameters

Растущие потребности в точности координатно-временных определений со стороны многих прикладных наук о Земле и практических задач приводят к необходимости постоянного совершенствования средств и методов определения и прогнозирования параметров вращения Земли. Параметр “всемирное время”, характеризующий фазу вращения Земли, в наибольшей степени среди других влияет на точность координатно-временных определений. В данной статье приводится описание применения метода сингулярного спектрального анализа к прогнозированию временных рядов параметров вращения Земли. Предлагается модификация базового метода, направленная на повышение точности прогноза. Выполнены сравнительные оценки точности прогнозов всемирного времени, рассчитанных методом сингулярного спектрального анализа, с аналогичными прогнозами Международной службы вращения Земли. Показана целесообразность применения метода сингулярного спектрального анализа для прогнозирования на интервалы более 50 дней Growing demand for accuracy of coordinate-time determinations from both many applied Earth sciences and practical problems requires the continuous improvement of means and methods for determining and predicting the parameters of the Earth rotation. Parameter “World time” characterizes phase of the Earth’s rotation and mostly affects the accuracy of coordinate-time determinations. This article describes application of method of singular spectral analysis for forecasting the time series of the Earth’s rotation parameters. We propose modification of basic method, which aims at increasing forecast accuracy. We made comparative estimates for accuracy of world time forecasts calculated by the method of singular spectral analysis with similar forecasts by the International Earth Rotation Service. The expediency of using the method of singular spectral analysis for predicting intervals of more than 50 days is shown

The motion of a lunar orbiter

1966 ◽  
Vol 25 ◽  
pp. 373
Author(s):  
Y. Kozai
Keyword(s):  
Degrees Of Freedom ◽  
Dimensional Space ◽  
Artificial Satellite ◽  
Equations Of Motion ◽  
Triaxial Ellipsoid ◽  
The Moon ◽  
Secular Motion ◽  
The Earth ◽  
Close Satellite ◽  
The Mean

The motion of an artificial satellite around the Moon is much more complicated than that around the Earth, since the shape of the Moon is a triaxial ellipsoid and the effect of the Earth on the motion is very important even for a very close satellite.The differential equations of motion of the satellite are written in canonical form of three degrees of freedom with time depending Hamiltonian. By eliminating short-periodic terms depending on the mean longitude of the satellite and by assuming that the Earth is moving on the lunar equator, however, the equations are reduced to those of two degrees of freedom with an energy integral.Since the mean motion of the Earth around the Moon is more rapid than the secular motion of the argument of pericentre of the satellite by a factor of one order, the terms depending on the longitude of the Earth can be eliminated, and the degree of freedom is reduced to one.Then the motion can be discussed by drawing equi-energy curves in two-dimensional space. According to these figures satellites with high inclination have large possibilities of falling down to the lunar surface even if the initial eccentricities are very small.The principal properties of the motion are not changed even if plausible values ofJ3andJ4of the Moon are included.This paper has been published in Publ. astr. Soc.Japan15, 301, 1963.

Formation of Lunar Craters and Bright Rays as a Result of Meteorite Impacts

1962 ◽  
Vol 14 ◽  
pp. 415-418
Author(s):  
K. P. Stanyukovich ◽  
V. A. Bronshten
Keyword(s):  
Explosive Charge ◽  
The Moon ◽  
Meteorite Impacts ◽  
The Earth ◽  
Lunar Craters ◽  
The Impact

The phenomena accompanying the impact of large meteorites on the surface of the Moon or of the Earth can be examined on the basis of the theory of explosive phenomena if we assume that, instead of an exploding meteorite moving inside the rock, we have an explosive charge (equivalent in energy), situated at a certain distance under the surface.

The Origin of the Moon

1962 ◽  
Vol 14 ◽  
pp. 149-155 ◽  
Author(s):  
E. L. Ruskol
Keyword(s):  
Chemical Composition ◽  
Solar System ◽  
The Moon ◽  
The Earth ◽  
The Difference ◽  
Origin Of The Moon

The difference between average densities of the Moon and Earth was interpreted in the preceding report by Professor H. Urey as indicating a difference in their chemical composition. Therefore, Urey assumes the Moon's formation to have taken place far away from the Earth, under conditions differing substantially from the conditions of Earth's formation. In such a case, the Earth should have captured the Moon. As is admitted by Professor Urey himself, such a capture is a very improbable event. In addition, an assumption that the “lunar” dimensions were representative of protoplanetary bodies in the entire solar system encounters great difficulties.

The Origin of the Moon and its Relationship to the Origin of the Solar System

1962 ◽  
Vol 14 ◽  
pp. 133-148 ◽  
Author(s):  
Harold C. Urey
Keyword(s):  
Solar System ◽  
The Moon ◽  
The Past ◽  
The Earth ◽  
Short Period ◽  
Origin Of The Moon

During the last 10 years, the writer has presented evidence indicating that the Moon was captured by the Earth and that the large collisions with its surface occurred within a surprisingly short period of time. These observations have been a continuous preoccupation during the past years and some explanation that seemed physically possible and reasonably probable has been sought.

Probable Structure and Nature of the Formations on the Reverse Side of the Moon According to Photometric Measurements of Lunar Photographs

1962 ◽  
Vol 14 ◽  
pp. 39-44
Author(s):  
A. V. Markov
Keyword(s):  
The Moon ◽  
Probable Structure ◽  
The Earth ◽  
Interplanetary Station ◽  
Photometric Measurements ◽  
Automatic Interplanetary Station

Notwithstanding the fact that a number of defects and distortions, introduced in transmission of the images of the latter to the Earth, mar the negatives of the reverse side of the Moon, indirectly obtained on 7 October 1959 by the automatic interplanetary station (AIS), it was possible to use the photometric measurements of the secondary (terrestrial) positives of the reverse side of the Moon in the experiment of the first comparison of the characteristics of the surfaces of the visible and invisible hemispheres of the Moon.

Seti Space Missions

1997 ◽  
Vol 161 ◽  
pp. 761-776 ◽  
Author(s):  
Claudio Maccone
Keyword(s):  
Electromagnetic Waves ◽  
Space Missions ◽  
Gravitational Lens ◽  
The Sun ◽  
Space Antenna ◽  
Focal Distance ◽  
Large Space ◽  
The Earth ◽  
Space Antennas ◽  
New Space

AbstractSETI from space is currently envisaged in three ways: i) by large space antennas orbiting the Earth that could be used for both VLBI and SETI (VSOP and RadioAstron missions), ii) by a radiotelescope inside the Saha far side Moon crater and an Earth-link antenna on the Mare Smythii near side plain. Such SETIMOON mission would require no astronaut work since a Tether, deployed in Moon orbit until the two antennas landed softly, would also be the cable connecting them. Alternatively, a data relay satellite orbiting the Earth-Moon Lagrangian pointL2would avoid the Earthlink antenna, iii) by a large space antenna put at the foci of the Sun gravitational lens: 1) for electromagnetic waves, the minimal focal distance is 550 Astronomical Units (AU) or 14 times beyond Pluto. One could use the huge radio magnifications of sources aligned to the Sun and spacecraft; 2) for gravitational waves and neutrinos, the focus lies between 22.45 and 29.59 AU (Uranus and Neptune orbits), with a flight time of less than 30 years. Two new space missions, of SETI interest if ET’s use neutrinos for communications, are proposed.

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