Gravity Probe B: Countdown to Launch

Everitt, C. W. F.; Buchman, Saps; DeBra, D.; Keiser, G. M.; Lockhart, J. M.; Muhlfelder, B.; Parkinson, Bradford W.; Turneaure, J. P.; team, Gravity Probe B

doi:10.1007/3-540-40988-2_4

Cited by 67 publications

(32 citation statements)

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“…In April 2004 the GP-B mission (Everitt et al 2001) has been launched. Its aim is the measurement of another gravitomagnetic effect, i.e.…”

Section: Introductionmentioning

confidence: 99%

The impact of the new Earth gravity models on the measurement of the Lense–Thirring effect with a new satellite

Iorio¹

2005

New Astronomy

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In this paper we investigate the opportunities offered by the new Earth gravity models from the dedicated CHAMP and, especially, GRACE missions to the project of measuring the general relativistic Lense-Thirring effect with a new Earth's artificial satellite. It turns out that it would be possible to abandon the stringent, and expensive, requirements on the orbital geometry of the originally prosed LARES mission (same semimajor axis a = 12270 km of the existing LAGEOS and inclination i = 70 deg) by inserting the new spacecraft in a relatively low, and cheaper, orbit (a = 7500 − 8000 km, i ∼ 70 deg) and suitably combining its node Ω with those of LAGEOS and LAGEOS II in order to cancel out the first even zonal harmonic coefficients of the multipolar expansion of the terrestrial gravitational potential J 2 , J 4 along with their temporal variations. The total systematic error due to the mismodelling in the remaining even zonal harmonics would amount to ∼ 1% and would be insensitive to departures of the inclination from the originally proposed value of many degrees. No semisecular long-period perturbations would be introduced because the period of the node, which is also the period of the solar K 1 tidal perturbation, would amount to ∼ 10 2 days. Since the coefficient of the node of the new satellite would be smaller than 0.1 for such low altitudes, the impact of the non-gravitational perturbations of it on the proposed combination would be negligible. Then, a particular financial and technological effort for suitably building the satellite in order to minimize the non-conservative accelerations would be unnecessary.

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“…In April 2004 the GP-B mission (Everitt et al 2001) has been launched. Its aim is the measurement of another gravitomagnetic effect, i.e.…”

Section: Introductionmentioning

confidence: 99%

The impact of the new Earth gravity models on the measurement of the Lense–Thirring effect with a new satellite

Iorio¹

2005

New Astronomy

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“…In recent years, there have been some attempts to measure these effects (see e.g. Ciufolini and Pavlis [13], Iorio [14] and references therein); in April 2004 Gravity Probe B was launched to accurately measure the frame dragging (and the geodetic precession) of an orbiting gyroscope: the final results are going to be published [15].…”

Section: Introductionmentioning

confidence: 99%

Gravitomagnetic gyroscope precession in Palatinif(R)gravity

Ruggiero

2009

Phys. Rev. D

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We study gravito-magnetic effects in the Palatini formalism of f (R) gravity. On using the Kerr-de Sitter metric, which is a solution of f (R) field equations, we calculate the impact of f (R) gravity on the gravito-magnetic precession of an orbiting gyroscope. We show that, even though an f (R) contribution is present in principle, its magnitude is negligibly small and far to be detectable in the present (like GP-B) and foreseeable space missions or observational tests around the Earth.

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“…Furthermore, detection of the extrinsic gravitomagnetic field probes the Lorentz invariance of the gravitational field which determines its causal nature, that is whether the fundamental speed limit c g for gravitational field (= the speed of gravity) is the same as the fundamental speed limit c for electromagentic field (= the speed of light). Experimental measurement of the intrinsic gravitomagnetic field of the rotating Earth is currently under way by the Gravity Probe B mission 9 with the expected accuracy of 1% or better 10 . Laser ranging of LAGEOS and other geodetic satellites verify its existence as predicted by Einstein's general relativity 11,12 although the claimed accuracy is rather controversial The goal of the present paper is to show that the extrinsic gravitomagnetic field can be measured in high-precision relativistic time-delay experiments where light (radio wave) interacts with the gravitational field of a moving massive body (gravitational lens) c .…”

Section: Introductionmentioning

confidence: 99%

Gravitomagnetism and the Speed of Gravity

Kopeikin

2006

Int. J. Mod. Phys. D

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Experimental discovery of the gravitomagnetic fields generated by translational and/or rotational currents of matter is one of primary goals of modern gravitational physics. The rotational (intrinsic) gravitomagnetic field of the Earth is currently measured by the Gravity Probe B. The present paper makes use of a parametrized post-Newtonian (PN) expansion of the Einstein equations to demonstrate how the extrinsic gravitomagnetic field generated by the translational current of matter can be measured by observing the relativistic time delay caused by a moving gravitational lens. We prove that measuring the extrinsic gravitomagnetic field is equivalent to testing relativistic effect of the aberration of gravity caused by the Lorentz transformation of the gravitational field. We unfold that the recent Jovian deflection experiment is a null-type experiment testing the Lorentz invariance of the gravitational field (aberration of gravity), thus, confirming existence of the extrinsic gravitomagnetic field associated with orbital motion of Jupiter with accuracy 20%. We comment on erroneous interpretations of the Jovian deflection experiment given by a number of researchers who are not familiar with modern VLBI technique and subtleties of JPL ephemeris. We propose to measure the aberration of gravity effect more accurately by observing gravitational deflection of light by the Sun and processing VLBI observations in the geocentric frame with respect to which the Sun is moving with velocity ∼ 30 km/s.

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Gravity Probe B: Countdown to Launch

Cited by 67 publications

References 0 publications

The impact of the new Earth gravity models on the measurement of the Lense–Thirring effect with a new satellite

The impact of the new Earth gravity models on the measurement of the Lense–Thirring effect with a new satellite

Gravitomagnetic gyroscope precession in Palatinif(R)gravity

Gravitomagnetism and the Speed of Gravity

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