Polar motion and earth tides from laser tracking

1977 ◽  
Vol 284 (1326) ◽  
pp. 485-494 ◽  
Keyword(s):  
Earth Tides ◽  
Length Of Day ◽  
Laser Tracking ◽  
The Earth ◽  
New Information ◽  
Single Station ◽  
Laser Systems ◽  
Rotation Of The Earth ◽  
Better Than

The tracking of near-Earth satellites with laser systems permits the determination of the variation of latitude of the tracking station and the variation in the rotation of the Earth. The present-day capability of a single station is approximately 75 cm in latitude averaged over 6h and 0.8 ms in the length of day. When the Laser Geodynamics Satellite (Lageos) is launched, a network of laser stations is projected to be able to achieve better than 10 cm in each coordinate from less than one day of tracking. The perturba­tions of near-Earth satellites by solid Earth and ocean tides are now measurable and can provide new information about the Earth and oceans. The orbit perturbations have long periods (days, months) and the analysis of orbital changes are providing estimates of the amplitudes and phases of the major tidal components.

scholarly journals Rotation of the Solar System Bodies

1992 ◽  
Vol 9 ◽  
pp. 508-536
Author(s):  
B. Kolaczek
Keyword(s):  
Solar System ◽  
Solid Body ◽  
Artificial Satellites ◽  
The Moon ◽  
The Earth ◽  
Photometric Observations ◽  
Solar System Bodies ◽  
Rotation Of The Earth ◽  
Better Than

Solar System bodies are different. They have different sizes, from large planets to small asteroids, and shapes. They have different structure, from solid body to solid body with fluid atmosphere or core, to gaseous bodies, but all of them rotate. The Solar System is a big laboratory for studying rotation of solid and fluid bodies.Different observational methods are applied to determine the rotation of the Solar system bodies. They depend on the position of the observer and on the structure of the bodies. The most accurate methods, laser ranging to the Moon and artificial satellites and Very Long Base radio Interferometry have been applied to the determination of the rotation of the Earth and the Moon. Their accuracy is better than 0.001”, which on the surface of the Earth corresponds to about 3 cm. Radiotracking of artifical satellites have been used for Earth, Moon, Venus, Mars. In the case of Jupiter, Saturn, Uranus, Neptune and Pluto-Charon magnetic and photometric observations have been used respectively. Their accuracy is of the order of one tenth of a degree.

scholarly journals Contribution Apportée par les Marées Terrestres Dans L'étude de la Rotation de la Terre

1968 ◽  
Vol 32 ◽  
pp. 71-76
Author(s):  
P. Melchior
Keyword(s):  
Experimental Study ◽  
Experimental Determination ◽  
Principal Axis ◽  
Liquid Core ◽  
Earth Tides ◽  
The Earth ◽  
Love Numbers ◽  
Rotation Of The Earth

Three aspects of the experimental study of earth-tides present a direct interest for the study of the rotation of the earth. These are (1) the experimental determination of the Love numbers and the dynamical effects of the liquid core on nutations of the principal axis of inertia; (2) the delay of earth-tides; and (3) the drift of horizontal pendulums.

Addendum 2020 to ‘Measurement of the Earth’s rotation: 720 BC to AD 2015’

2021 ◽  
Vol 477 (2246) ◽  
pp. 20200776
Author(s):  
L. V. Morrison ◽  
F. R. Stephenson ◽  
C. Y. Hohenkerk ◽  
M. Zawilski
Keyword(s):  
Angular Momentum ◽  
Earth’S Rotation ◽  
The Sun ◽  
Earth's Rotation ◽  
Moon System ◽  
Link Type ◽  
The Earth ◽  
Solar Eclipses ◽  
Rotation Of The Earth

Historical reports of solar eclipses are added to our previous dataset (Stephenson et al. 2016 Proc. R. Soc. A 472 , 20160404 ( doi:10.1098/rspa.2016.0404 )) in order to refine our determination of centennial and longer-term changes since 720 BC in the rate of rotation of the Earth. The revised observed deceleration is −4.59 ± 0.08 × 10 −22  rad s −2 . By comparison the predicted tidal deceleration based on the conservation of angular momentum in the Sun–Earth–Moon system is −6.39 ± 0.03 × 10 −22  rad s −2 . These signify a mean accelerative component of +1.8 ± 0.1 × 10 −22  rad s −2 . There is also evidence of an oscillatory variation in the rate with a period of about 14 centuries.

scholarly journals Commission 19: Rotation of the Earth

1985 ◽  
Vol 19 (1) ◽  
pp. 193-205 ◽  
Author(s):  
Ya. S. Yatskiv ◽  
W. J. Klepczynski ◽  
F. Barlier ◽  
H. Enslin ◽  
C. Kakuta ◽  
...  
Keyword(s):  
Time Frame ◽  
Laser Ranging ◽  
Earth’S Rotation ◽  
The Moon ◽  
Earth's Rotation ◽  
The Earth ◽  
Long Time ◽  
Terrestrial Reference System ◽  
Rotation Of The Earth

During the period, work on the problem of the Earth’s rotation has continued to expand and increase its scope. The total number of institutions engaged in the determination of the Earth’s rotation parameters (ERP) by different techniques has been increased significantly. The rotation of the Earth is currently measured by classical astrometry, Doppler and laser satellite tracking, laser ranging of the Moon, and radio interferometry. Several long time series of the ERP are available from most of these techniques, in particular, those made during the Main Campaign of the MERIT project. The various series have been intercompared and their stability, in the time frame of years to days, has been estimated for the purposes of establishing a new conventional terrestrial reference system (COTES). On the other hand, the difficulties of maintaining a regular operation for laser ranging to the Moon (LLR) have been recognized. It resulted in the proposal to organize an one-month campaign of observations in 1985 in order to complement the COTES collocation program and to allow additional intercomparisons with other techniques.

scholarly journals New Determination of the “Decade” Fluctuations in the Rotation of the Earth 1860–1978

1979 ◽  
Vol 82 ◽  
pp. 55-57
Author(s):  
L. V. Morrison
Keyword(s):  
Angular Momentum ◽  
Electromagnetic Coupling ◽  
Viscous Stress ◽  
Mantle Boundary ◽  
Core Mantle Boundary ◽  
Topographic Features ◽  
The Core ◽  
The Earth ◽  
Rotation Of The Earth

Observations of the Earth's rotation have shown irregular variations of rate which have characteristic times of decades. These have been attributed to transfer of angular momentum between core and mantle by some mechanism such as inertial coupling, viscous stress, electromagnetic coupling or stresses produced by topographic features on the core mantle boundary.

Causes of fluctuations in the rotation of the Earth

1984 ◽  
Vol 313 (1524) ◽  
pp. 95-105 ◽  
Keyword(s):  
Pole Position ◽  
Length Of Day ◽  
Tidal Effects ◽  
Short Term ◽  
The Earth ◽  
Closing The Gap ◽  
Rotation Of The Earth ◽  
Observational Techniques ◽  
Made In ◽  
Structure Properties

Over the last decade considerable progress has been made in closing the gap between geophysical theory and the observed changes in the Earth's spin rate and polar motion, which are affected by the Earth’s internal structure, properties and processes. New observational techniques and data have had a marked impact on understanding the short-term variations in the length of day and pole position, but we can expect between another 5 and 30 years to pass before they permit improved explanations of longer-term phenomena (18.6 year tidal effects, the Markowitz wobble, decade fluctuations in the length of day, etc.) This review summarizes recent advances, problems newly illuminated by recent Earth rotation data (for example mantle anelasticity, core-mantle coupling) and problems still unresolved.

scholarly journals In-Orbit Attitude Determination of the UVSQ-SAT CubeSat Using TRIAD and MEKF Methods

Sensors ◽  
2021 ◽  
Vol 21 (21) ◽  
pp. 7361
Author(s):  
Adrien Finance ◽  
Christophe Dufour ◽  
Thomas Boutéraon ◽  
Alain Sarkissian ◽  
Antoine Mangin ◽  
...  
Keyword(s):  
Attitude Determination ◽  
Spacecraft Attitude ◽  
Small Satellite ◽  
Infrared Sensors ◽  
High Quantum Efficiency ◽  
Small Satellites ◽  
The Earth ◽  
Spatio Temporal ◽  
Better Than

Ultraviolet and infrared sensors at high quantum efficiency on-board a small satellite (UVSQ-SAT) is a CubeSat dedicated to the observation of the Earth and the Sun. This satellite has been in orbit since January 2021. It measures the Earth’s outgoing shortwave and longwave radiations. The satellite does not have an active pointing system. To improve the accuracy of the Earth’s radiative measurements and to resolve spatio-temporal fluctuations as much as possible, it is necessary to have a good knowledge of the attitude of the UVSQ-SAT CubeSat. The attitude determination of small satellites remains a challenge, and UVSQ-SAT represents a real and unique example to date for testing and validating different methods to improve the in-orbit attitude determination of a CubeSat. This paper presents the flight results of the UVSQ-SAT’s attitude determination. The Tri-Axial Attitude Determination (TRIAD) method was used, which represents one of the simplest solutions to the spacecraft attitude determination problem. Another method based on the Multiplicative Extended Kalman Filter (MEKF) was used to improve the results obtained with the TRIAD method. In sunlight, the CubeSat attitude is determined at an accuracy better than 3° (at one σ) for both methods. During eclipses, the accuracy of the TRIAD method is 14°, while it reaches 10° (at one σ) for the recursive MEKF method. Many future satellites could benefit from these studies in order to validate methods and configurations before launch.

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