Orbit determination by solving for gravity parameters with multiple arc data

Wu, Jiun-Tsong

doi:10.2514/3.20838

Cited by 5 publications

(5 citation statements)

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“…This is equivalent to modeling clocks as white noise processes, a procedure that produces independent clock solutions at each time step. The estimation algorithm then combines multiple-arc data and proceeds in three steps [Wu, 1985]. First, the Householder transformation is applied (again) to each arc to eliminate the arc-dependent parameters and to obtain derived data for the arc-common parameters, for example, the bin parameters.…”

Section: Analysis Proceduresmentioning

confidence: 99%

“…The bin technique allows two methods to convert the bin parameters to a gravity model in the form of a spherical expansion. The positional adjustments can be differentiated with respect to time to give the local gravity field, as shown in equation (3), and the field can be further transformed into the expansion coefficients [Wu, 1985]. Alternatively, the bin parameters can be converted directly into the coefficients through a least squares estimation .…”

Section: Units In Milligalsmentioning

confidence: 99%

“…proach, proposed in 1985 and the subject of this paper, takes advantage of repeat orbit characteristics [Wu, 1985;]. This technique introduces an ad hoc set of positional parameters and exploits two properties of the TOPEX orbit: (1) that over a single orbit, gravity is the only significant source of dynamic modeling error and (2) that the ground track is designed to repeat every 10 days.…”

mentioning

confidence: 99%

“…The mathematical details are given by Wu [1985]. With additional effort the bin technique can be extended to convert the pertubations in position from all ground tracks in the 10-day repeat cycle into the gravity field at the satellite altitude, which can further be transformed into a standard model in terms of a spherical harmonic expansion [Wu, 1985;Wu et al, 1990]. Here we present results of covariance analysis for orbit and gravity field determination with this technique.…”

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confidence: 99%

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TOPEX orbit determination and gravity recovery using global positioning system data from repeat orbits

Wu¹,

Yunck²

1992

J. Geophys. Res.

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A covariance analysis is presented for satellite tracking and gravity recovery with a differential Global Positioning System-based technique to be demonstrated on TOPEX in the early 1990s. The technique employs data from an ensemble of repeat ground tracks to recover a unique satellite epoch state for each track and a set of invariant positional parameters common to all tracks. The positional parameters represent the effect of mismodeled gravitational field on the satellite orbit. At an altitude of 1336 km, where gravity modeling is the dominant systematic error, averaging of random error over many arcs and adjustment of the gravity model reduce the final satellite position error. The positional parameters can then be used to produce a refined global gravity model. The analysis indicates that errors ranging from 5 to 8 cm in TOPEX altitude and 0.05 to 0.2 mGal for the gravity field can be achieved, depending on the number of repeat arcs used. INTRODUCTIONNASA's Ocean Topography Experiment (TOPEX) will carry an orbiting radar altimeter to measure sea surface height, with the primary goal of charting global ocean circulation [Born et al., , 1985. TOPEX will fly in a 1336-km circular orbit inclined at 66.1 ø. The altimeter measurements, averaged over a several kilometer footprint, will be precise to about 2.5 cm. In order to make maximum use of the precise altimetry it is necessary to independently track the satellite geocentric altitude with comparably high precision. The baseline tracking system for TOPEX is a global network of laser-ranging systems which is expected to deliver about 13-cm altitude accuracy for TOPEX [Born et al., , 1985. In addition, an experimental tracking system employing the Global Positioning System (GPS) will be used in a special demonstration. The experimental system will make use of an on-board GPS receiver operating in concert with a network of six ground receivers distributed around the globe [Lichten et al., 1985]. A number of estimation techniques have been proposed to determine the TOPEX orbit using the GPS data [Yunck et al., 1990; Melbourne et al., 1986]. The most thoroughly studied techniques are variations on the traditional dynamic technique which requires the use of accurate force models. Systematic errors in the force models lead directly to systematic errors in the orbit solution. At the 1336-km TOPEX altitude, which is well above the regime of significant atmospheric drag, errors in the model for the Earth's gravity field are the major source of dynamic orbit error [Lichten et al., 1985; Wu et al., 1986].Because it provides continuous coverage with accurate measurements, the GPS system allows alternative tracking techniques which are less dependent on the nominal dynamic models. Two recently proposed alternatives to dynamic orbit estimation, the kinematic and reduced dynamic techniques Wu et al., 1991], make use of geometric information in GPS observations to greatly reduce the sensitivity to force model errors. A third ap-

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Section: Analysis Proceduresmentioning

confidence: 99%

Section: Units In Milligalsmentioning

confidence: 99%

mentioning

confidence: 99%

mentioning

confidence: 99%

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TOPEX orbit determination and gravity recovery using global positioning system data from repeat orbits

Wu¹,

Yunck²

1992

J. Geophys. Res.

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“…For the first time, high-precision tracking data will be acquired continuously over the entire globe, including the vast ocean basins and extensive land masses in eastern Europe and Asia that are now inaccessible to western ground-based tracking systems. To quantify the information contained in the TOPEX/ Poseidon GPS data set, we have developed new processing techniques which we call the "gravity bin algorithm" [Wu, 1992;Wu and Wu, 1992 TOPEX/Poseidon will carry a dual-frequency microwave altimeter accurate to a few centimeters for measuring ocean topography. The scientific potential of this precise altimetry can be fully realized only if the TOPEX/Poseidon geocentric altitude can be independently determined to a few centimeters [Born et al, 1985].…”

Section: Introductionmentioning

confidence: 99%

Gravity field improvement using global positioning system data from TOPEX/Poseidon: A covariance analysis

Bertiger¹,

Wu²,

Wu³

1992

J. Geophys. Res.

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The TOPEX/Poseidon satellite (inclination 65 ø, period 113 min) is scheduled for launch in 1992 to study the world's ocean topography through precise altimetric measurements. It will also carry an experimental Global Positioning System (GPS) receiver to demonstrate precise orbit determination with GPS. Data for the GPS experiment will be collected by the on-board receiver and a worldwide network of ground receivers. These data may also be used to improve the knowledge of the Earth's gravitational field. The GPS data are especially useful for improving the gravity field over the world's oceans, where the current tracking data are sparse. Using a realistic scenario for processing 10 days of GPS data, we perform a covariance analysis to obtain the expected improvement to the GEM-T2 gravity field. The large amount of GPS data and the large number of parameters (1979 parameters for the gravity field, plus carrier phase biases, etc.) require special filtering techniques for efficient solution. We have used the gravity bin technique introduced earlier to compute the covariance matrix associated with the spherical harmonic gravity field. The covariance analysis shows that the GPS data from one 10-day arc of TOPEX/Poseidon with no a priori constraints can resolve medium degree and order (3-26) parameters with sigmas (standard deviations) that are an order of magnitude smaller than the corresponding sigmas of GEM-T2. When the information from GEM-T2 is combined with the TOPEX/Poseidon GPS measurements, an order of magnitude improvement is observed in low-and medium-degree terms with significant improvements spread over a wide range of degree and order.

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The Multi-Stage-Lambert Scheme for steering a satellite-launch vehicle (SLV)

Kamal

2008

2008 IEEE International Multitopic Conference

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Orbit determination by solving for gravity parameters with multiple arc data

Cited by 5 publications

References 10 publications

TOPEX orbit determination and gravity recovery using global positioning system data from repeat orbits

TOPEX orbit determination and gravity recovery using global positioning system data from repeat orbits

Gravity field improvement using global positioning system data from TOPEX/Poseidon: A covariance analysis

The Multi-Stage-Lambert Scheme for steering a satellite-launch vehicle (SLV)

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