The Flyby Anomaly in an Extended Whitehead’s Theory

2017

Astrophys Space Sci

The flyby anomaly is a persistent riddle in astrodynamics. Orbital analysis in several flybys of the Earth since the Galileo spacecraft flyby of the Earth in 1990 have shown that the asymptotic post-encounter velocity exhibits a difference with the initial velocity that cannot be attributed to conventional effects. To elucidate its origin, we have developed an orbital program for analyzing the trajectory of the spacecraft in the vicinity of the perigee, including both the Sun and the Moon's tidal perturbations and the geopotential zonal, tesseral and sectorial harmonics provided by the EGM96 model. The magnitude and direction of the anomalous acceleration acting upon the spacecraft can be estimated from the orbital determination program by comparing with the trajectories fitted to telemetry data as provided by the mission teams. This acceleration amounts to a fraction of a mm/s 2 and decays very fast with altitude. The possibility of some new physics of gravity in the altitude range for spacecraft flybys is discussed.

Section: Discussionsupporting

confidence: 86%

Anomalous accelerations in spacecraft flybys of the Earth

2017

Astrophys Space Sci

“…In previous works we have proposed an extended model of Whitehead's and Whitehead‐Synge's models (Coleman, 2005; Whitehead, 2007) with the objective of quantitative a quantitive prediction for the flyby anomaly (Acedo, 2015; Bel, 2007, 2015). Although the predictions of our model agree only in order of magnitude, it must be emphasized that they come from a model without any free parameter.…”

Section: Introductionmentioning

confidence: 99%

On a correlation among azimuthal velocities and the flyby anomaly sign

Bel

2017

Astron Nachr

Data of six flybys, those of Galileo I, Galileo II, NEAR, Cassini, Rosetta and Messenger were reported by Anderson et al \citep{Anderson}. Four of them: Galileo I, NEAR, Rosetta and Messenger gain Newtonian energy during the flyby transfer, while Galileo II and Cassini lose energy. This is, in both cases, a surprising anomaly since Newtonian forces derive from a potential and they are, therefore, conservative. We show here that the gravitational field of a rotating planet as derived from a new model introduces a non conservative force that gives a partial, but in our opinion satisfactory, explanation of these anomalies and suggests a correlation between the sign of the anomaly and the sign of the azimuthal velocity at perigee.Comment: 12 pages, 3 figure

“…where µ, R are the mass constant and radius of the planet, Ω is the angular velocity with respect to the fixed stars and r the distance of the spacecraft to the center. It was shown that this model yields a qualitative agreement with the measured anomalies in several flybys of the Earth [1]. If we apply this expression to the case of Jupiter, by taking into account that r ≃ R = 71492 km at the perijove and that the Jupiter's angular velocity is Ω = 2π/T , T = 9.9259 hours [53], we get δa = 1.0396 mm/s 2 .…”

Section: Sources Of Error and Interpretation Of The Resultsmentioning

confidence: 60%

“…Some models have suggested that the Earth's gravitational field is distorted by an unknown extra term, not taken into account in General Relativity, and that this can be interpreted as a force field with a range of a few hundred kms [5]. In the model by Acedo and Bel [1,6] an anomalous azimuthal component of the gravity acceleration is proposed. The magnitude of this extra acceleration is given by:…”

Section: Sources Of Error and Interpretation Of The Resultsmentioning

confidence: 99%

A possible flyby anomaly for Juno at Jupiter

Advances in Space Research

Piqueras

Moraño

2018

In the last decades there have been an increasing interest in improving the accuracy of spacecraft navigation and trajectory data. In the course of this plan some anomalies have been found that cannot, in principle, be explained in the context of the most accurate orbital models including all known effects from classical dynamics and general relativity. Of particular interest for its puzzling nature, and the lack of any accepted explanation for the moment, is the flyby anomaly discovered in some spacecraft flybys of the Earth over the course of twenty years. This anomaly manifest itself as the impossibility of matching the pre and post-encounter Doppler tracking and ranging data within a single orbit but, on the contrary, a difference of a few mm/s in the asymptotic velocities is required to perform the fitting.Nevertheless, no dedicated missions have been carried out to elucidate the origin of this phenomenon with the objective either of revising our understanding of gravity or to improve the accuracy of spacecraft Doppler tracking by revealing a conventional origin.With the occasion of the Juno mission arrival at Jupiter and the close flybys of this planet, that are currently been performed, we have developed an orbital model suited to the time window close to the * E-mail: luiacrod@imm.upv.es 1 perijove. This model shows that an anomalous acceleration of a few mm/s 2 is also present in this case. The chance for overlooked conventional or possible unconventional explanations is discussed.