Gravity Probe B orbit determination

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The Gravity Probe B mission provided two new quantitative tests of Einstein’s theory of gravity, general relativity (GR), by cryogenic gyroscopes in Earth’s orbit. Data from four gyroscopes gave a geodetic drift-rate of −6601.8 ± 18.3 marc-s yr−1 and a frame-dragging of −37.2 ± 7.2 marc-s yr−1, to be compared with GR predictions of −6606.1 and −39.2 marc-s yr−1 (1 marc-s = 4.848 × 10−9 radians). The present paper introduces the science, engineering, data analysis, and heritage of Gravity Probe B, detailed in the accompanying 20 CQG papers.

“…GPS receiver. Every 10 s a GPS receiver provided GPS time and the position and velocity of the Spacecraft for the exact orbit determination described in paper 17 [31].…”

Section: Science Datamentioning

confidence: 99%

The Gravity Probe B test of general relativity

Everitt

Muhlfelder

DeBra

et al. 2015

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“…were used to calculate the instantaneous values of g Ω ⃗ and fd Ω ⃗ (in fact, the J 2 correction to the frame-dragging was negligible). These were computed for every orbit from the precise GPS orbit data [21] using each available valid data point. The averages found differed slightly from orbit to orbit due its small classical variation, so we Ω 〈 〉and ns Ω 〈 〉 were additionally averaged over all orbits, and relativistic drift rate predictions were determined from the result given by the formulas (11).…”

Section: ≡ ×mentioning

confidence: 99%

“…( ) μ⃗ being the misalignment vector (21). Here we used expression (27) for ψ , took ψ equal to μ according to equation (26), and introduced the torque coefficient ( ) ( ) taking into account that H l0 is real.…”

Section: C2 Pe Torques On the Spinning Rotor Inside Rolling Housing: ...mentioning

confidence: 99%

Gravity Probe B data analysis: I. Coordinate frames and analysis models

Silbergleit

Turneaure

Conklin

et al. 2015

Gravity Probe B (GP-B) was a cryogenic, space-based experiment testing the geodetic and frame-dragging predictions of Einstein's theory of general relativity (GR) by means of gyroscopes in Earth orbit. This first of three data analysis papers reviews the GR predictions and details the models that provide the framework for the relativity analysis. In the second paper we describe the flight data and their preprocessing. The third paper covers the algorithms and software tools that fit the preprocessed flight data to the models to give the experimental results published in Everitt et al (2011 Phys. Rev. Lett. 106 221101–4).

“…The uncertainties in the predicted drift rates for the GP-B gyroscopes are dominated by the uncertainty in the S/C orbit. S/C position and velocity were determined using on-board GPS [24]. The data were fit in 30 h-long batches.…”

Section: 43mentioning

confidence: 99%

“…Figure24. Relativistic drift rate estimates for gyroscope 3 using only data from individual segments (colored ellipses) and using all segments (black ellipse).…”

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confidence: 99%

Gravity Probe B data analysis: III. Estimation tools and analysis results

Conklin¹,

Heifetz²,

Holmes³

et al. 2015

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This paper provides detailed descriptions of the numerical estimation algorithms used to fit physics-based models to the data from the Gravity Probe B spacecraft, as well as the scientific results of the experiment, and the statistical and systematic uncertainties. The first paper in this series of three data analysis papers derives the mathematical expressions for the signals to be analyzed, and the second paper deals with science data acquisition and their preparation for the relativistic drift rate estimation. The data from each of the four gyroscopes are partitioned into six segments, each spanning several weeks to several months. These segments are first analyzed individually to check the validity of the mathematical models and the accuracy of the estimation routine by examining the consistency of the relativistic drift rate estimates from each of these 24 gyro-segments. Then, the drift rate estimates and uncertainties are calculated for each individual gyroscope and for the four gyroscopes combined. These results are presented and compared with each other and with the prediction of general relativity.