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More Spacecraft Velocity Anomalies
ZonkerWilliam recommends a bulletin from the American Institute of Physics, which discusses a study noting that recent spacecraft, such as NEAR, appear to display velocity anomalies much like those seen in Pioneer 10 (which were observed beginning ten years ago). The anomalies amount to up to 13 mm/sec., with a measurement accuracy of 0.1 mm/sec. Quoting: "A new look at the trajectories for various spacecraft as they fly past the Earth finds in each case a tiny amount of surplus velocity. For craft that pursue a path mostly symmetrical with respect to the equator, the effect is minimal. For craft that pursue a more unsymmetrical path, the effect is larger."
Occasionally this is also quoted as ending with 'Hmm, that's funny'.
According to this, the acceleration anomaly can't be accounted for by dark matter.
Equine Mammals Are Considerably Smaller
The precision of the measurements is 0.1 mm/sec, not the accuracy. Those are different things.
The range isn't an issue, it's how accurately they can measure doppler. The standard technique is to transmit a special signal to the spacecraft, which retransmits it to the Earth, like an RF mirror. This allows them to use extremely stable ground-based oscillators, like Hydrogen masers. This signal can also be modulated with a PN code to allow precise range measurements.
Mea navis aericumbens anguillis abundat
The Earth does indeed gain mass continuously from in-falling space dust, captured solar wind, etc., and as a consequence of GR, our clocks should be getting slower over time relative to distant satellites. However, I would think that the effect is not sufficient to account for the observed velocity discrepancy. I am just a lowly programmer, but I would be very surprised if those physicists have not taken this into account or discounted this accordingly.
Life's a tale told by an idiot, full of sound and fury, signifying nothing.
The Pioneer 10 and 11 speed-position anomalies, unaccounted drift, were noticed by the late 70's. NASA and the peole involved just didn't discuss it with the public until much later, after many potential sources of error and theoretical possiblities had been analyzed. That is when I first heard it mentioned, in Houston, ca 1977-78.
I can't speak to this specific case, but someone did a study several years ago of the Voyager anomaly and whether it could be a gravitational effect. The gist of the analysis was the if it were gravitational, it would also affect the distribution of long-period comets, especially the "new" ones from the Oort cloud. They calculated the effect you'd expect and it's much too large relative to what we see in the comets, so whatever is affecting Voyager pretty much cannot be gravitational in nature.
It's also worth noting that even in the mega-analysis by Anderson et al. concluded that although they couldn't determine a source for the anomaly, they still generally felt that it was more likely to be endogenic than exogenic.