Determination of Some Physical Parameters of the Moon with Lunar Laser Ranging Data

1997 ◽  
pp. 221-226
Author(s):  
Jin Wenjing ◽  
Li Jinling
Keyword(s):  
Laser Ranging ◽  
Physical Parameters ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Lunar Laser

scholarly journals Determination of Some Physical Parameters of the Moon with Lunar Laser Ranging Data

1997 ◽  
Vol 165 ◽  
pp. 221-226
Author(s):  
Jin Wenjing ◽  
Li Jinling
Keyword(s):  
Gravitational Field ◽  
Laser Ranging ◽  
Physical Parameters ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Moments Of Inertia ◽  
Lunar Interior ◽  
Lunar Laser

AbstractInformation about the structure of lunar interior and evolution could be obtained from measurements of lunar free librations, gravitational field, dissipation etc. In this paper the precision of determining free librations from Lunar Laser Ranging (LLR) data are estimated. Using the observing data from four telescopes for eighteen years, the amplitudes and phases of free librations, and ratios of the moments of inertia of the Moon were determined.

scholarly journals Benefit of New High-Precision LLR Data for the Determination of Relativistic Parameters

Universe ◽  
2021 ◽  
Vol 7 (2) ◽  
pp. 34
Author(s):  
Liliane Biskupek ◽  
Jürgen Müller ◽  
Jean-Marie Torre
Keyword(s):  
Equivalence Principle ◽  
Gravitational Constant ◽  
Lunar Orbit ◽  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Lunar Laser ◽  
Infra Red ◽  
Ppn Parameters

Since 1969, Lunar Laser Ranging (LLR) data have been collected by various observatories and analysed by different analysis groups. In the recent years, observations with bigger telescopes (APOLLO) and at infra-red wavelength (OCA) are carried out, resulting in a better distribution of precise LLR data over the lunar orbit and the observed retro-reflectors on the Moon. This is a great advantage for various investigations in the LLR analysis. The aim of this study is to evaluate the benefit of the new LLR data for the determination of relativistic parameters. Here, we show current results for relativistic parameters like a possible temporal variation of the gravitational constant G˙/G0=(−5.0±9.6)×10−15yr−1, the equivalence principle with Δmg/miEM=(−2.1±2.4)×10−14, and the PPN parameters β−1=(6.2±7.2)×10−5 and γ−1=(1.7±1.6)×10−4. The results show a significant improvement in the accuracy of the various parameters, mainly due to better coverage of the lunar orbit, better distribution of measurements over the lunar retro-reflectors, and last but not least, higher accuracy of the data. Within the estimated accuracies, no violation of Einstein’s theory is found and the results set improved limits for the different effects.

Effect of non-tidal station loading on Lunar Laser Ranging observatories and on the estimation of Earth orientation parameters

2021 ◽  
Author(s):  
Vishwa Vijay Singh ◽  
Liliane Biskupek ◽  
Jürgen Müller ◽  
Mingyue Zhang
Keyword(s):  
Research Centre ◽  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Earth Orientation Parameters ◽  
Tidal Station ◽  
Earth Orientation ◽  
The Earth ◽  
Lunar Laser ◽  
Orientation Parameters

<p>The distance between the observatories on Earth and the retro-reflectors on the Moon has been regularly observed by the Lunar Laser Ranging (LLR) experiment since 1970. In the recent years, observations with bigger telescopes (APOLLO) and at infra-red wavelength (OCA) are carried out, resulting in a better distribution of precise LLR data over the lunar orbit and the observed retro-reflectors on the Moon, and a higher number of LLR observations in total. Providing the longest time series of any space geodetic technique for studying the Earth-Moon dynamics, LLR can also support the estimation of Earth orientation parameters (EOP), like UT1. The increased number of highly accurate LLR observations enables a more accurate estimation of the EOP. In this study, we add the effect of non-tidal station loading (NTSL) in the analysis of the LLR data, and determine post-fit residuals and EOP. The non-tidal loading datasets provided by the German Research Centre for Geosciences (GFZ), the International Mass Loading Service (IMLS), and the EOST loading service of University of Strasbourg in France are included as corrections to the coordinates of the LLR observatories, in addition to the standard corrections suggested by the International Earth Rotation and Reference Systems Service (IERS) 2010 conventions. The Earth surface deforms up to the centimetre level due to the effect of NTSL. By considering this effect in the Institute of Geodesy (IfE) LLR model (called ‘LUNAR’), we obtain a change in the uncertainties of the estimated station coordinates resulting in an up to 1% improvement, an improvement in the post-fit LLR residuals of up to 9%, and a decrease in the power of the annual signal in the LLR post-fit residuals of up to 57%. In a second part of the study, we investigate whether the modelling of NTSL leads to an improvement in the determination of EOP from LLR data. Recent results will be presented.</p>

scholarly journals MILLIMETRE MOON MEASUREMENT: 50 YEARS OF LUNAR LASER RANGING SINCE APOLLO 11!

2020 ◽  
Vol XLIII-B3-2020 ◽  
pp. 1105-1110
Author(s):  
J. F. Brock
Keyword(s):  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
The Earth ◽  
Space Race ◽  
Lunar Laser ◽  
Space Star ◽  
Gravitational Influence ◽  
Tv Shows ◽  
Set Up

Abstract. Since the dawn of time the Moon has held fascination for the earliest humans who saw it as a natural navigational beacon, a heavenly body to be revered and a poetic inspiration. Ancient art features the Moon as a prominent subject from all epochs and genres. The name “lunatic” infers that it drives men insane. Giant tides and rapid recessions of water are all attributed to its gravitational influence. As a young boy I was thrilled by stories of Moon travel like Jules Verne’s “From the Earth to the Moon” plus TV shows and movies such as “Lost in Space”, “Star Trek” and “Dr. Who.”The Russian-American “Space Race” focussed on the exciting possibility of man landing on the Moon. I cannot forget the live telecast of the Apollo 11 astronauts on the Moon’s surface in 1969 when I was 13 years old. Four years later I decided to be a land boundary surveyor trained in precise measurement for land title creation. My curiosity was alerted to the Apollo 11 laser ranging aspect of the project when the US team set up a bank of retro-reflectors for measurements from powerful devices on the Earth in the same way we Earthly surveyors make our daily measurements using such EDM equipment.In this paper I will describe the techniques and equipment utilised during this accurate Moon positioning project. You will also see the Earth observatories still measuring to five sites on the Moon and some ancient admirable attempts to determine this distance.

scholarly journals Combination of data from different space geodetic systems for the determination of Earth rotation parameters

1988 ◽  
Vol 128 ◽  
pp. 233-239
Author(s):  
Brent A. Archinal
Keyword(s):  
Earth Rotation ◽  
Normal Equation ◽  
Laser Ranging ◽  
Weighted Mean ◽  
Lunar Laser Ranging ◽  
Long Baseline ◽  
Lunar Laser ◽  
Earth Rotation Parameters ◽  
Vlbi Data

Simulation experiments have been performed in order to compare the Earth Rotation Parameter (ERP) results obtained from a) individual observational systems, b) the weighted mean of the results from a), and c) all of the observational data, via the combination of the normal equations obtained in a). These experiments included the use of 15 days of simulated Lunar Laser Ranging (LLR), Satellite Laser Ranging (SLR) to Lageos, and Very Long Baseline Interferometry (VLBI) data using realistic station positions and accuracies. Under the assumptions chosen, the normal equation combination solutions usually provide the best ERP over recovery periods of 6 and 12 hours, and 1, 2, and 5 days. However, solutions by the weighted mean (and even by VLBI alone) provide results that are nearly as good, i.e., within a factor of one to two in accuracy. Complete details are presented in [Archinal, 1987].

The free librations of a dissipative Moon

1981 ◽  
Vol 303 (1477) ◽  
pp. 327-338 ◽  
Keyword(s):  
Rotation Axis ◽  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Fluid Friction ◽  
Tidal Friction ◽  
Fluid Turbulence ◽  
Lunar Laser ◽  
Solid Friction ◽  
Lunar Core

Dissipation in the Moon produces a small offset, ca. 0.23", of the Moon's rotation axis from the plane defined by the ecliptic and lunar orbit normals. Both solid body tidal friction and viscous fluid friction at a core—mantle interface are plausible mechanisms. In this paper, I discuss the merits of each and find that solid friction requires a low lunar tidal Q , ca . 28, while turbulent fluid friction requires a core of radius 330 km to cause the signature observed by lunar laser ranging. Large ( ca . 0.4—8.0") free librations of the lunar figure have also been detected by laser ranging. Both a very recent impact on the Moon and fluid turbulence in the lunar core are plausible mechanisms for generating these free librations.

scholarly journals A review of the lunar laser ranging technique and contribution of timing systems

2016 ◽  
Vol Volume 112 (Number 3/4) ◽  
Author(s):  
Cilence Munghemezulu ◽  
Ludwig Combrinck ◽  
Joel O. Botai ◽  
◽  
◽  
...  
Keyword(s):  
Reference Frames ◽  
Laser Pulses ◽  
Relativity Theory ◽  
Earth Tides ◽  
Laser Ranging ◽  
The Moon ◽  
Lunar Laser Ranging ◽  
Factors Affecting ◽  
Lunar Laser ◽  
Space Geodetic Techniques

Abstract The lunar laser ranging (LLR) technique is based on the two-way time-of-flight of laser pulses from an earth station to the retroreflectors that are located on the surface of the moon. We discuss the ranging technique and contribution of the timing systems and its significance in light of the new LLR station currently under development by the Hartebeesthoek Radio Astronomy Observatory (HartRAO). Firstly, developing the LLR station at HartRAO is an initiative that will improve the current geometrical network of the LLR stations which are presently concentrated in the northern hemisphere. Secondly, data products derived from the LLR experiments – such as accurate lunar orbit, tests of the general relativity theory, earth–moon dynamics, interior structure of the moon, reference frames, and station position and velocities – are important in better understanding the earth–moon system. We highlight factors affecting the measured range bias such as the effect of earth tides on station position and delays induced by timing systems, as these must be taken into account during the development of the LLR analysis software. HartRAO is collocated with other fundamental space geodetic techniques which makes it a true fiducial geodetic site in the southern hemisphere and a central point for further development of space-based techniques in Africa. Furthermore, the new LLR will complement the existing techniques by providing new niche areas of research both in Africa and internationally.

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