59 research outputs found
The flyby anomaly: A case for strong gravitomagnetism?
In the last two decades an anomalous variation in the asymptotic velocity of spacecraft performing a flyby manoeuvre around
Earth has been discovered through careful Doppler tracking and orbital analysis. No viable hypothesis for a conventional explanation
of this effect has been proposed and its origin remains unexplained. In this paper we discuss a strong transversal component of the
gravitomagnetic field as a possible source of the flyby anomaly. We show that the perturbations induced by such a field could fit the
anomalies both in sign and order of magnitude. But, although the secular contributions to the Gravity Probe B experimental results
and the Lense Thirring effect in geodynamics satellites can be made null, the detailed orbital evolution is easily in conflict with such
an enhanced gravitomagnetic effect.Acedo RodrĂguez, L. (2014). The flyby anomaly: A case for strong gravitomagnetism?. Advances in Space Research. 54(4):788-796. doi:10.1016/j.asr.2014.04.014S78879654
Phenomenology of the Lense-Thirring effect in the Solar System
Recent years have seen increasing efforts to directly measure some aspects of
the general relativistic gravitomagnetic interaction in several astronomical
scenarios in the solar system. After briefly overviewing the concept of
gravitomagnetism from a theoretical point of view, we review the performed or
proposed attempts to detect the Lense-Thirring effect affecting the orbital
motions of natural and artificial bodies in the gravitational fields of the
Sun, Earth, Mars and Jupiter. In particular, we will focus on the evaluation of
the impact of several sources of systematic uncertainties of dynamical origin
to realistically elucidate the present and future perspectives in directly
measuring such an elusive relativistic effect.Comment: LaTex, 51 pages, 14 figures, 22 tables. Invited review, to appear in
Astrophysics and Space Science (ApSS). Some uncited references in the text
now correctly quoted. One reference added. A footnote adde
Gravity Probe B: Final Results of a Space Experiment to Test General Relativity
Gravity Probe B, launched 20 April 2004, is a space experiment testing two
fundamental predictions of Einstein's theory of General Relativity (GR), the
geodetic and frame-dragging effects, by means of cryogenic gyroscopes in Earth
orbit. Data collection started 28 August 2004 and ended 14 August 2005.
Analysis of the data from all four gyroscopes results in a geodetic drift rate
of -6,601.8+/- 18.3 mas/yr and a frame-dragging drift rate of -37.2 +/- 7.2
mas/yr, to be compared with the GR predictions of -6,606.1 mas/yr and -39.2
mas/yr, respectively (`mas' is milliarc-second; 1mas = 4.848 x 10-9 rad)
The Attitude Determination and Control Subsystem of the STC (Satellite Television Corporation) Direct Broadcast Satellite
GLucocorticoids inhibit the generation of leukocyte procoagulant (tissue factor) activity
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