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B Anomalous accelerations in spacecraft flybys of the Earth

  1. Nov 9, 2017 #1

    wolram

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    The suggestion is a fifth force to counter these anomalies is this generally excepted?

    arXiv:1711.02875 [pdf, ps, other]
    Anomalous accelerations in spacecraft flybys of the Earth
    L. Acedo
    Comments: 41 pages, 11 figures (Accepted for publication in Astrophysics and Space Science)
    Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

    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/s2 and decays very fast with altitude. The possibility of some new physics of gravity in the altitude range for spacecraft flybys is discussed.
     
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  3. Nov 9, 2017 #2

    Drakkith

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    I think the possibility of this being the result of a fifth fundamental force is extremely remote.
     
  4. Nov 9, 2017 #3

    sophiecentaur

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    Yep. You can only introduce an idea like that when absolutely all other mundane cause have been eliminated - and I don't think they have been.
     
  5. Nov 9, 2017 #4

    phyzguy

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    This is reminiscent of the Pioneer Anomaly. There were similar tiny deviations of the path of the Pioneer spacecraft from what was predicted. Dozens (maybe hundreds?) of papers were written speculating that it was due to modifications of gravity, MOND, and whatever else you might want to invent. In the end, careful thermal modeling of the spacecraft showed that the effect was due to radiation pressure from the asymmetric radiation of the heat from the Radioisotope Thermal Generator. I'm with Drakkith and sophiecentaur. I strongly doubt that there is any new physics here.
     
  6. Nov 10, 2017 #5

    wolram

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    IMHO, They have considered all possible scenarios , May be some one can come up with another one?
     
  7. Nov 10, 2017 #6

    phyzguy

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    Everyone thought all possible explanations had been considered for the Pioneer anomaly until someone came up with the right one. I'll give you a couple of possibilities:

    (1) The model of the Earth's gravitational field that they are using was developed at a point in time. There is no reason to expect the Earth's mass distribution to be static. Water movements, ice movements, magma movements inside the Earth all would cause changes over time.

    (2) How about impacts from small particles of orbital debris in low Earth orbit? We know it's a mess up there.

    (3) Do they really know the atmospheric drag that well? They admit that atmospheric drag can account for about half of the Galileo anomaly. Maybe the atmospheric drag is really twice what they think. I know there are cases of satellites in low Earth orbit coming down sooner than expected because the orbit decayed more rapidly than expected.
     
  8. Nov 11, 2017 #7
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