An assessment of relativistic effects for low Earth orbiters: the GRACE satellites

Larson, Kristine M.; Ashby, Neil; Hackman, Christine; Bertiger, Willy

doi:10.1088/0026-1394/44/6/007

Cited by 41 publications

(29 citation statements)

References 15 publications

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“…71 The distance is also independently determined by geodetic-quality GPS receivers on the GRACE satellites. 71,72 Viewed from the ECI perspective, the leading satellite moves away from the light signal sent by the lagging satellite, while the lagging satellite moves towards the light signal sent by the leading satellite. Calculating the speed of light based on the instantaneous distance between the satellites and the observed light propagation times produces anisotropic values that are described by the Sagnac correction.…”

Section: Ast Is Compatible With Light Speed Anisotropies Observed In mentioning

confidence: 99%

An approach to directly probe simultaneity

Kipreos

Balachandran

2016

Mod. Phys. Lett. A

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The theory of special relativity derives from the Lorentz transformation. The Lorentz transformation implies differential simultaneity and light speed isotropy. Experiments to probe differential simultaneity should be able to distinguish the Lorentz transformation from a kinematically-similar alternate transformation that predicts absolute simultaneity, the absolute Lorentz transformation. Here, we describe how published optical tests of light speed isotropy/anisotropy cannot distinguish between the two transformations. We show that the shared equations of the two transformations, from the perspective of the "stationary" observer, are sufficient to predict null results in optical resonator experiments and in tests of frequency changes in one-way light paths. In an influential 1910 exposition on differential simultaneity, Comstock described how a "stationary" observer would observe different clock readings for spatially-separated "moving" clocks. The difference in clock readings is an integral aspect of differential simultaneity. We derive the equation for the difference in clock readings and show that it is equivalent to the Sagnac correction that describes light speed anisotropies in satellite communications. We describe an experimental strategy that can measure the differences in spatially-separated clock times to allow a direct probe of the nature of simultaneity.

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Section: Ast Is Compatible With Light Speed Anisotropies Observed In mentioning

confidence: 99%

An approach to directly probe simultaneity

Kipreos

Balachandran

2016

Mod. Phys. Lett. A

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“…For GPS satellite clocks, only a periodic component needs to be corrected based on the Keplerian orbit assumption (Petit et al, 2010). However, LEO satellites, e.g., GRACE satellites, will be more affected by time-varying non-spherical earth gravity, especially by J 2 effects (Larson et al, 2007). Fortunately, the relativistic effects have been corrected in the observations generated in the Level 1B RINEX file of GRACE mission.…”

Section: Grace Flight Data Processingmentioning

confidence: 99%

Enhancing the kinematic precise orbit determination of low earth orbiters using GPS receiver clock modelling

Yang

Yue

Yuan

et al. 2014

Advances in Space Research

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“…It is therefore necessary to use a numerical integration procedure to take J 2 into account. A more general expression for the relativistic effects of LEO satellite clocks is given in [12].…”

Section: Relativistic Clock Effectsmentioning

confidence: 99%

GPS Receiver Clock Modelling for Kinematic-Based Precise Orbit Determination of Low Earth Orbiters

Yang

Yue

et al. 2014

China Satellite Navigation Conference (CSNC) 2014 Proceedings: Volume III

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This paper describes a GPS receiver clock model that can improve the accuracy of kinematic orbit determination for spacecraft in low earth orbit. The receiver clock error is commonly estimated on an epoch-by-epoch basis, along with the satellite's position. However, due to the high correlation between the spacecraft orbit altitude and the receiver clock parameters, estimates of the radial component are degraded in the kinematic-based approach. Using clocks with high stability, e.g., ultra-stable oscillators, the highly predictable frequency behaviour of the receiver oscillator can be fully exploited to improve the positioning accuracy, especially for the radial component. A simple two-state model is used to describe the deterministic and stochastic property of the receiver clock. In particular, the clock parameters are estimated as time offset and frequency offset. Additionally, residual non-deterministic random errors such as frequency white noise, flicker noise and random-walk noise are modelled. The test results of GRACE flight data indicate that the positioning accuracy could be improved significantly. In particular, the radial component error was reduced by over 60 %.

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An assessment of relativistic effects for low Earth orbiters: the GRACE satellites

Cited by 41 publications

References 15 publications

An approach to directly probe simultaneity

An approach to directly probe simultaneity

Enhancing the kinematic precise orbit determination of low earth orbiters using GPS receiver clock modelling

GPS Receiver Clock Modelling for Kinematic-Based Precise Orbit Determination of Low Earth Orbiters

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