Probing the Earth’s gravity field by means of satellite-to-satellite tracking

1977 ◽  
Vol 284 (1326) ◽  
pp. 475-483 ◽  
Keyword(s):  
Gravity Field ◽  
Signal To Noise Ratio ◽  
Gravity Anomalies ◽  
Small Variation ◽  
Satellite Tracking ◽  
Practical Advantage ◽  
Earth’S Gravity Field ◽  
Ground Station ◽  
Local Gravity ◽  
Range Rate

The idea of tracking one spacecraft from another grew out of some tracking studies performed early in the Apollo programme (1962-3). The main practical advantage of such a technique is that ( a ) contact time with a low orbiting spacecraft can be increased considerably (approximately 50 min v . 5 min for a single ground station); ( b ) the number of ground stations can be reduced; ( c ) the dependency on stations on foreign soil can almost be eliminated; and ( d ) detailed studies of spacecraft motions due to small variations in the Earth’s gravity field (anomalies) may be detectable. This paper describes specifically two satellite-to-satellite tracking (s. s. t.) tests, namely ( a ) the ATS-6/Geos-3 and ( b ) the ATS-6/Apollo-Soyuz experiment and some of the results obtained. The main purpose of these two experiments was first to track via ATS-6 the Geos-3 as well as the Apollo-Soyuz and to use these tracking data to determine ( a ) both orbits, that is, ATS-6, Geos-3 and/or the Apollo-Soyuz orbits at the same time; ( b ) each of these orbits alone, and ( c ) test the ATS-6/Geos-3 and /or Apollo-Soyuz s. s. t. link to study local gravity anomalies; and, second, to test communications, command and data transmission from the ground via ATS-6 to these spacecraft and back again to the ground (Rosman, N. G.). Most of the interesting data obtained to date originate from the Apollo-Soyuz geodynamics experiment. Thus, it will be discussed in some detail. Gravity anomalies of say 3-5 mGal (3-5 × 10 -5 m s -2 ) or larger having wavelength of 500-1000 km on the Earth’s surface are important for studies of the upper layers of the earth. Such anomalies were actually ‘seen’ for the first time from space as signatures in the form of very small variation (order of ~ 1 to 2 cm/s) in the range rate between ATS-6, Geos-3 and Apollo-Soyuz. Since the measured range noise turned out to be only 0.03- 0.05 cm/s on the average, these signatures were detected with an excellent signal-to-noise ratio. Orbit determination examples using s. s. t. data from ATS-6 and Geos-3 are also discussed in detail together with errors associated with the orbits of Geos-3. Further, signature studies and gravity anomaly detections with s. s. t. data will be shown and discussed in detail.

Using the Digital Models of Gravity Anomalies for Zoning of the Earth’s Gravity Field

2018 ◽  
Vol 54 (6) ◽  
pp. 964-970
Author(s):  
V. N. Koneshov ◽  
S. A. Krylov ◽  
D. S. Loginov ◽  
V. B. Nepoklonov
Keyword(s):  
Gravity Field ◽  
Gravity Anomalies ◽  
Digital Models ◽  
Earth’S Gravity Field ◽  
Models Of Gravity

Earth's Gravity Field Derived from Grace Satellite Tracking Data

2006 ◽  
Vol 49 (3) ◽  
pp. 651-656 ◽  
Author(s):  
Xu-Hua ZHOU ◽  
Houtse HSU ◽  
Bin WU ◽  
Bi-Bo PENG ◽  
Yang LU
Keyword(s):  
Gravity Field ◽  
Satellite Tracking ◽  
Tracking Data ◽  
Earth’S Gravity Field ◽  
Grace Satellite

Processing of GRACE FO satellite to satellite tracking data using the GRACE SIGMA software

2020 ◽  
Author(s):  
Mathias Duwe ◽  
Igor Koch ◽  
Jakob Flury ◽  
Akbar Shabanloui
Keyword(s):  
Gravity Field ◽  
Satellite Tracking ◽  
Background Modeling ◽  
Gravity Potential ◽  
Laser Ranging ◽  
Tracking Data ◽  
Variational Equations ◽  
Range Rate ◽  
Orbit Types ◽  
Computing Approach

<p>At our Institute we compute monthly gravity potential solutions from GRACE/GRACE-FO level 1B data by using the variational equations approach. The gravity field is recovered with our own MATLAB software "GRACE-SIGMA" that was recently updated in order to reduce the calculation time with parallel computing approach by approx. 80%. Also the processing chain has changed to update the background modeling and we made tests with different orbit types and different parametrizations. We discuss progress to include laser ranging interferometer data in gravity field solutions. We present validation results and analyze the properties of postfit range-rate residuals.</p>

scholarly journals GRAVITY ANOMALY ASSESSMENT USING GGMS AND AIRBORNE GRAVITY DATA TOWARDS BATHYMETRY ESTIMATION

2016 ◽  
Vol XLII-4/W1 ◽  
pp. 287-297
Author(s):  
A. Tugi ◽  
A. H. M. Din ◽  
K. M. Omar ◽  
A. S. Mardi ◽  
Z. A. M. Som ◽  
...  
Keyword(s):  
Gravity Anomaly ◽  
Gravity Field ◽  
Ocean Circulation ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Airborne Gravity ◽  
Satellite Gravity ◽  
Earth’S Gravity Field ◽  
Explorer Mission ◽  
Satellite Gravity Missions

The Earth’s potential information is important for exploration of the Earth’s gravity field. The techniques of measuring the Earth’s gravity using the terrestrial and ship borne technique are time consuming and have limitation on the vast area. With the space-based measuring technique, these limitations can be overcome. The satellite gravity missions such as Challenging Mini-satellite Payload (CHAMP), Gravity Recovery and Climate Experiment (GRACE), and Gravity-Field and Steady-State Ocean Circulation Explorer Mission (GOCE) has introduced a better way in providing the information on the Earth’s gravity field. From these satellite gravity missions, the Global Geopotential Models (GGMs) has been produced from the spherical harmonics coefficient data type. The information of the gravity anomaly can be used to predict the bathymetry because the gravity anomaly and bathymetry have relationships between each other. There are many GGMs that have been published and each of the models gives a different value of the Earth’s gravity field information. Therefore, this study is conducted to assess the most reliable GGM for the Malaysian Seas. This study covered the area of the marine area on the South China Sea at Sabah extent. Seven GGMs have been selected from the three satellite gravity missions. The gravity anomalies derived from the GGMs are compared with the airborne gravity anomaly, in order to figure out the correlation (R<sup>2</sup>) and the root mean square error (RMSE) of the data. From these assessments, the most suitable GGMs for the study area is GOCE model, GO_CONS_GCF_2_TIMR4 with the R<sup>2</sup> and RMSE value of 0.7899 and 9.886 mGal, respectively. This selected model will be used in the estimating the bathymetry for Malaysian Seas in future.

scholarly journals An Analysis of Choosing Gravity Anomalies for Solving Problems in Geodesy, Geophysics and Environmental Engineering

2020 ◽  
Author(s):  
Vytautas Puškorius ◽  
Eimuntas Paršeliūnas ◽  
Petras Petroškevičius ◽  
Romuald Obuchovski
Keyword(s):  
Gravity Field ◽  
Gravity Anomalies ◽  
Environmental Engineering ◽  
Correct Selection ◽  
Earth’S Gravity Field ◽  
The Earth ◽  
Pure Gravity ◽  
Geodynamic Processes ◽  
Selection Of

Gravity anomalies provide valuable information about the Earth‘s gravity field. They are used for solving various geophysical and geodetic tasks, mineral and oil exploration, geoid and quasi-geoid determination, geodynamic processes of Earth, determination of the orbits of various objects, moving in space around the Earth etc. The increasing accuracy of solving the above mentioned problems poses new requirements for the accuracy of the gravity anomalies. Increasing the accuracy of gravity anomalies can be achieved by gaining the accuracy of the gravimetric and geodetic measurements, and by improving the methodology of the anomalies detection. The modern gravimetric devices allow to measure the gravity with an accuracy of several microgals. Space geodetic systems allow to define the geodetic coordinates and ellipsoidal heights of gravimetric points within a centimeter accuracy. This opens up the new opportunities to calculate in practice both hybrid and pure gravity anomalies and to improve their accuracy. In this context, it is important to analyse the possibilities of detecting various gravity anomalies and to improve the methodology for detecting gravity anomalies. Also it is important the correct selection of the gravity anomalies for different geodetic, geophysical and environmental engineering tasks. The modern gravity field data of the territory of Lithuania are used for the research.

scholarly journals Application of Radial Basis Functions for Height Datum Unification

Geosciences ◽  
2018 ◽  
Vol 8 (10) ◽  
pp. 369 ◽  
Author(s):  
Ismael Foroughi ◽  
Abdolreza Safari ◽  
Pavel Novák ◽  
Marcelo Santos
Keyword(s):  
Gravity Field ◽  
Satellite Altimetry ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Basis Functions ◽  
Gravity Potential ◽  
Field Modelling ◽  
Marine Gravity ◽  
Local Gravity ◽  
Local Gravity Field Modelling

Local gravity field modelling demands high-quality gravity data as well as an appropriate mathematical model. Particularly in coastal areas, there may be different types of gravity observations available, for instance, terrestrial, aerial, marine gravity, and satellite altimetry data. Thus, it is important to develop a proper tool to merge the different data types for local gravity field modelling and determination of the geoid. In this study, radial basis functions, as a commonly useful tool for gravity data integration, are employed to model the gravity potential field of the southern part of Iran using terrestrial gravity anomalies, gravity anomalies derived from re-tracked satellite altimetry, marine gravity anomalies, and gravity anomalies synthesized from an Earth gravity model. Reference GNSS/levelling (geometric) geoidal heights are used to evaluate the accuracy of the estimated local gravity field model. The gravimetric geoidal heights are in acceptable agreement with the geometric ones in terms of the standard deviation and the mean value which are 4.1 and 12 cm, respectively. Besides, the reference benchmark of the national first-order levelling network of Iran is located in the study area. The derived gravity model was used to compute the gravity potential difference at this point and then transformed into a height difference which results in the value of the shift of this benchmark with respect to the geoid. The estimated shift shows a good agreement with previously published studies.

scholarly journals COMPUTATION OF GRAVITY FIELD FUNCTIONALS WITH A LOCALIZED LEVEL ELLIPSOID

2021 ◽  
Vol 6 (24) ◽  
pp. 226-242
Author(s):  
Chivatsi Jonathan Nyoka ◽  
Ami Hassan Md Din ◽  
Muhammad Faiz Pa’suya
Keyword(s):  
Gravity Field ◽  
Spherical Harmonic ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Earth’S Gravity Field ◽  
Geopotential Models ◽  
Gravity Disturbances ◽  
Zero Degree ◽  
Equipotential Surfaces ◽  
Best Fit

The description of the earth’s gravity field is usually expressed in terms of spherical harmonic coefficients, derived from global geopotential models. These coefficients may be used to evaluate such quantities as geoid undulations, gravity anomalies, gravity disturbances, deflection of the vertical, etc. To accomplish this, a global reference normal ellipsoid, such as WGS84 and GRS80, is required to provide the computing reference surface. These global ellipsoids, however, may not always provide the best fit of the local geoid and may provide results that are aliased. In this study, a regional or localized geocentric level ellipsoid is used alongside the EGM2008 to compute gravity field functionals in the state of Johor. Residual gravity field quantities are then computed using GNSS-levelled and raw gravity data, and the results are compared with both the WGS84 and the GRS80 equipotential surfaces. It is demonstrated that regional level ellipsoids may be used to compute gravity field functionals with a better fit, provided the zero-degree spherical harmonic is considered. The resulting residual quantities are smaller when compared with those obtained with global ellipsoids. It is expected that when the remove-compute-restore method is employed with such residuals, the numerical quadrature of the Stoke’s integral may be evaluated on reduced gravity anomalies that are smoother compared to when global equipotential surfaces are used

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