scholarly journals Drift of the Earth’s Principal Axes of Inertia from GRACE and Satellite Laser Ranging Data

2020 ◽  
Vol 12 (2) ◽  
pp. 314
Author(s):  
José M. Ferrándiz ◽  
Sadegh Modiri ◽  
Santiago Belda ◽  
Mikhail Barkin ◽  
Mathis Bloßfeld ◽  
...  
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
Navigation Systems ◽  
Time Varying ◽  
Stationary Case ◽  
Principal Axes ◽  
Initial Location ◽  
Gravity Recovery

The location of the Earth’s principal axes of inertia is a foundation for all the theories and solutions of its rotation, and thus has a broad effect on many fields, including astronomy, geodesy, and satellite-based positioning and navigation systems. That location is determined by the second-degree Stokes coefficients of the geopotential. Accurate solutions for those coefficients were limited to the stationary case for many years, but the situation improved with the accomplishment of Gravity Recovery and Climate Experiment (GRACE), and nowadays several solutions for the time-varying geopotential have been derived based on gravity and satellite laser ranging data, with time resolutions reaching one month or one week. Although those solutions are already accurate enough to compute the evolution of the Earth’s axes of inertia along more than a decade, such an analysis has never been performed. In this paper, we present the first analysis of this problem, taking advantage of previous analytical derivations to simplify the computations and the estimation of the uncertainty of solutions. The results are rather striking, since the axes of inertia do not move around some mean position fixed to a given terrestrial reference frame in this period, but drift away from their initial location in a slow but clear and not negligible manner.

scholarly journals Geocentric Terrestrial Reference Frame Accuracy: DSN Spacecraft Tracking and VLBI/Lunar Laser Ranging

1988 ◽  
Vol 128 ◽  
pp. 115-120 ◽  
Author(s):  
A. E. Niell
Keyword(s):  
Reference Frame ◽  
Terrestrial Reference Frame ◽  
Spin Axis ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Deep Space Network ◽  
Long Baseline ◽  
Lunar Laser ◽  
Spacecraft Tracking ◽  
Geocentric Coordinates

From a combination of 1) the location of McDonald Observatory from Lunar Laser Ranging, 2) relative station locations obtained from Very Long Baseline Interferometry (VLBI) measurements, and 3) a short tie by traditional geodesy, the geocentric coordinates of the 64 m antennas of the NASA/JPL Deep Space Network are obtained with an orientation which is related to the planetary ephemerides and to the celestial radio reference frame. Comparison with the geocentric positions of the same antennas obtained from tracking of interplanetary spacecraft shows that the two methods agree to 20 cm in distance off the spin axis and in relative longitude. The orientation difference of a 1 meter rotation about the spin axis is consistent with the error introduced into the tracking station locations due to an error in the ephemeris of Jupiter.

scholarly journals Impact of network constraining on the terrestrial reference frame realization based on SLR observations to LAGEOS

2019 ◽  
Vol 93 (11) ◽  
pp. 2293-2313 ◽  
Author(s):  
R. Zajdel ◽  
K. Sośnica ◽  
M. Drożdżewski ◽  
G. Bury ◽  
D. Strugarek
Keyword(s):  
Reference Frame ◽  
A Priori ◽  
Terrestrial Reference Frame ◽  
Laser Ranging ◽  
Potential Core ◽  
North East ◽  
The North ◽  
Station Coordinates ◽  
Earth Rotation Parameters ◽  
Variable List

Abstract The Satellite Laser Ranging (SLR) network struggles with some major limitations including an inhomogeneous global station distribution and uneven performance of SLR sites. The International Laser Ranging Service (ILRS) prepares the time-variable list of the most well-performing stations denoted as ‘core sites’ and recommends using them for the terrestrial reference frame (TRF) datum realization in SLR processing. Here, we check how different approaches of the TRF datum realization using minimum constraint conditions (MCs) and the selection of datum-defining stations affect the estimated SLR station coordinates, the terrestrial scale, Earth rotation parameters (ERPs), and geocenter coordinates (GCC). The analyses are based on the processing of the SLR observations to LAGEOS-1/-2 collected between 2010 and 2018. We show that it is essential to reject outlying stations from the reference frame realization to maintain a high quality of SLR-based products. We test station selection criteria based on the Helmert transformation of the network w.r.t. the a priori SLRF2014 coordinates to reject misbehaving stations from the list of datum-defining stations. The 25 mm threshold is optimal to eliminate the epoch-wise temporal deviations and to provide a proper number of datum-defining stations. According to the station selection algorithm, we found that some of the stations that are not included in the list of ILRS core sites could be taken into account as potential core stations in the TRF datum realization. When using a robust station selection for the datum definition, we can improve the station coordinate repeatability by 8%, 4%, and 6%, for the North, East and Up components, respectively. The global distribution of datum-defining stations is also crucial for the estimation of ERPs and GCC. When excluding just two core stations from the SLR network, the amplitude of the annual signal in the GCC estimates is changed by up to 2.2 mm, and the noise of the estimated pole coordinates is substantially increased.

scholarly journals 100 kHz satellite laser ranging demonstration at Matera Laser Ranging Observatory

2021 ◽  
Vol 95 (2) ◽  
Author(s):  
Daniele Dequal ◽  
Costantino Agnesi ◽  
David Sarrocco ◽  
Luca Calderaro ◽  
Luigi Santamaria Amato ◽  
...  
Keyword(s):  
Repetition Rate ◽  
Attitude Determination ◽  
Terrestrial Reference Frame ◽  
High Repetition Rate ◽  
Low Earth Orbit ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
Single Shot ◽  
Time Jitter ◽  
Main Instrument

AbstractThe new challenges related to the monitoring of Earth’s shape and motion have led the global geodetic observing system to set more stringent requirements on the precision and stability of the terrestrial reference frame (TRF). The achievement of this ambitious goal depends on the improvement of space geodesy techniques, satellite laser ranging (SLR) in particular, being the main instrument for TRF realization. In this work, we study the potential of very high repetition rate SLR by performing a data acquisition campaign with an Ekspla “Atlantic 60” 100 kHz repetition rate laser at the Matera Laser Ranging Observatory (MLRO). This system constitutes an increase of two orders of magnitude in repetition rate with respect to the current SLR stations, while maintaining a good single-shot timing performance. The system has been active for 4 consecutive nights, consistently tracking several low Earth orbit satellites as well as LAGEOS 1 and 2. The results have shown a single-shot time jitter close to other stations, but with unprecedented statistics for $$\approx 10$$ ≈ 10 ps single-shot precision. The analysis of the residuals of LAGEOS satellites allowed us to identify multiple peaks, due to the retroflection from different corner cubes. This opens up the possibility of attitude determination of retroreflector arrays, as well as a new method for spin rate measurement.

Local tie survey of the SLR and GNSS stations at the Shimosato Hydrographic Observatory

2021 ◽  
Author(s):  
Shun-ichi Watanabe ◽  
Yuto Nakamura ◽  
Yusuke Yokota ◽  
Akira Suzuki ◽  
Haruka Ueshiba ◽  
...  
Keyword(s):  
New Zealand ◽  
Reference Frame ◽  
Rotation Angle ◽  
Terrestrial Reference Frame ◽  
Coast Guard ◽  
Laser Ranging ◽  
Geospatial Information ◽  
Rotation Axes ◽  
Local Tie ◽  
Observation Results

<p>The Japan Coast Guard (JCG) operates Satellite Laser Ranging (SLR) and GNSS observation at the Shimosato Hydrographic Observatory (SHO) in Wakayama Prefecture, Japan. The SLR and GNSS observation results obtained at the SHO are submitted to the ILRS and the IGS, respectively, and have contributed to the development of the International Terrestrial Reference Frame (ITRF). The SHO, operating two types of global geodetic observation, is now one of the sites of the Global Geodetic Observing System (GGOS).</p><p>Observation sites such as the SHO that operate multiple geodetic techniques function as co-location sites, where the different geodetic techniques can be linked together by precisely determining the local tie between these techniques. In November 2020, the JCG and the Geospatial Information Authority of Japan (GSI) have performed a local tie survey at the SHO to determine the local tie between the SLR telescope and the GNSS station. In our survey, we mounted several targets on the SLR telescope, which we observed from four survey sites that were temporarily set in the SHO. During the survey, we rotated the telescope along the azimuth and the elevation axes at fixed intervals, observing the target positions for each rotation angle. The measured target positions form arcs, from which we can estimate the rotation axes of the telescope; the origin of the axes was determined as the center of the SLR telescope. For the calculation of the local tie, we used the software pyaxis, developed by Land Information New Zealand (LINZ).</p><p>In our presentation, we will show the methods of our survey and calculation described above, and the estimated local tie vector. As of January 2021, we are preparing to submit the co-location SINEX file to the IERS, to contribute to the construction of the upcoming ITRF2020.</p>

scholarly journals The mobile laser-ranging system as a comparative tool for monitoring the terrestrial reference frame

1988 ◽  
Vol 128 ◽  
pp. 147-151
Author(s):  
Peter Wilson
Keyword(s):  
Reference Frame ◽  
Earth Rotation ◽  
Systematic Errors ◽  
Terrestrial Reference Frame ◽  
Laser Ranging ◽  
Computational Techniques ◽  
The Status

The proposed earth rotation service and the related efforts to monitor the terrestral reference frame will employ instrumental and computational techniques of widely different kinds. It has already been demonstrated that the results produced by these techniques are sensitive to systematic errors occurring at the level of a few millimeters. As a result it will be extremely important to verify the performance of the different systems by making comparative observations at the same sites. Only mobile laser-ranging systems are currently in a position to perform this kind of service. To demonstrate the status of laser ranging during co-location, this paper presents a proposal for a controlled collocation experiment involving U.S. and European stations of the IRIS network.

scholarly journals Tropospheric and range biases in Satellite Laser Ranging

2021 ◽  
Vol 95 (9) ◽  
Author(s):  
Mateusz Drożdżewski ◽  
Krzysztof Sośnica
Keyword(s):  
Reference Frame ◽  
Measurement Errors ◽  
Single Photon ◽  
Global Scale ◽  
Satellite Laser Ranging ◽  
Laser Ranging ◽  
Bias Effect ◽  
Distance Measurements ◽  
Station Coordinates ◽  
Geocenter Motion

AbstractThe Satellite Laser Ranging (SLR) technique provides very accurate distance measurements to artificial Earth satellites. SLR is employed for the realization of the origin and the scale of the terrestrial reference frame. Despite the high precision, SLR observations can be affected by various systematic errors. So far, range biases were used to account for systematic measurement errors and mismodeling effects in SLR. Range biases are constant for all elevation angles and independent of the measured distance to a satellite. Recently, intensity-dependent biases for single-photon SLR detectors and offsets of barometer readings and meteorological devices were reported for some SLR stations. In this paper, we study the possibility of the direct estimation of tropospheric biases from SLR observations to LAGEOS satellites. We discuss the correlations between the station heights, range biases, tropospheric biases, and their impact on the repeatability of station coordinates, geocenter motion, and the global scale of the reference frame. We found that the solution with the estimation of tropospheric biases provides more stable station coordinates than the solution with the estimation of range biases. From the common estimation of range and tropospheric biases, we found that most of the systematic effects at SLR stations are better absorbed by elevation-dependent tropospheric biases than range biases which overestimate the total bias effect. The estimation of tropospheric biases changes the SLR-derived global scale by 0.3 mm and the geocenter coordinates by 1 mm for the Z component, causing thus an offset in the realization of the reference frame origin. Estimation of range biases introduces an offset in some SLR-derived low-degree spherical harmonics of the Earth’s gravity field. Therefore, considering elevation-dependent tropospheric and intensity biases is essential for deriving high-accuracy geodetic parameters.

scholarly journals Using satellite laser ranging to measure ice mass change in Greenland and Antarctica

2018 ◽  
Vol 12 (1) ◽  
pp. 71-79 ◽  
Author(s):  
Jennifer A. Bonin ◽  
Don P. Chambers ◽  
Minkang Cheng
Keyword(s):  
Time Series ◽  
Mass Loss ◽  
Time Frame ◽  
Satellite Laser Ranging ◽  
Mass Change ◽  
Laser Ranging ◽  
Data Types ◽  
Gravity Recovery ◽  
Loss Estimate

Abstract. A least squares inversion of satellite laser ranging (SLR) data over Greenland and Antarctica could extend gravimetry-based estimates of mass loss back to the early 1990s and fill any future gap between the current Gravity Recovery and Climate Experiment (GRACE) and the future GRACE Follow-On mission. The results of a simulation suggest that, while separating the mass change between Greenland and Antarctica is not possible at the limited spatial resolution of the SLR data, estimating the total combined mass change of the two areas is feasible. When the method is applied to real SLR and GRACE gravity series, we find significantly different estimates of inverted mass loss. There are large, unpredictable, interannual differences between the two inverted data types, making us conclude that the current 5×5 spherical harmonic SLR series cannot be used to stand in for GRACE. However, a comparison with the longer IMBIE time series suggests that on a 20-year time frame, the inverted SLR series' interannual excursions may average out, and the long-term mass loss estimate may be reasonable.

Where - A Software for geodetic Analysis

2020 ◽  
Author(s):  
Ingrid Fausk ◽  
Michael Dähnn ◽  
Ann-Silje Kirkvik
Keyword(s):  
Reference Frame ◽  
Software Package ◽  
Very Long Baseline Interferometry ◽  
Terrestrial Reference Frame ◽  
Test Phase ◽  
Laser Ranging ◽  
Operational Analysis ◽  
Long Baseline ◽  
Analysis Center ◽  
To Receive

<p><em>Where</em> is a software package developed by the Norwegian Mapping Authority (NMA). The software will provide a useful contribution to the International Terrestrial Reference Frame, by analysis of data from Very-long-baseline Interferometry (VLBI) and Satellite Laser Ranging (SLR).</p><div><em>Where</em> is written in Python, and is taking advantage of well-tested code like the SOFA and IERS libraries. The architecture is easily maintainable and extendable. Python makes it easy to write, and utilizes external libraries written in faster languages.</div><div> </div><div>Both the NMA and the Instituto Geografico Nacional, Spain, are in a test phase of deliveries of VLBI analysis results to the IVS with the <em>Where</em> software. After some improvements of the software, we will also deliver analysis results to the ILRS. Our goal is to receive full status as operational analysis center for both VLBI and SLR, and to contribute to ITRF2020.</div><div> </div><div>Sharing and cooperating with other institutions is made possible by making <em>Where</em> an open source project on GitHub.</div>

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