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Mild mannered
2009-Nov-25, 11:14 AM
Hi all,
Re: the flyby anomaly in the latest news letter - I'm sure all the basic suggestions have been tossed around already but I couldn't see anything concerning distribution of mass - I'm sure I saw a Gravity map sometime that showed an interpretation of the Earth's Gravity field and it wasn't uniform - it was skewed off to one side because of course the Earth - whilst a sphere - doesn't have its mass evenly distributed - since the Earth is spinning could it simply be that sometimes the flyby occurs because the craft is passing the stronger gravity section of the Earth and at other times the weaker?
Also - what about the position of the Moon and its Gravity effects? Do these add to the problem from various relative positions?
Mild

Jens
2009-Nov-25, 11:32 AM
I think that's one possibility. Of course, we have to remember that experts are studying this, and have tried hard to rule that out. So the fact that it remains as a problem implies that it seems improbably that those effects would be strong enough to create the anomaly.

Interestingly, the latest Rosetta flyby showed no anomaly.

Mild mannered
2009-Nov-25, 11:59 AM
Sure, I appreciate the experts are unlikely to have missed this option - I was just interested in the article and remembered the earlier one showing the Gravity map.

I thought maybe the reason the effect was sporadic could be explained by this if the effects were relevant (again, I assume they've been all over this, but I couldn't see any info)

borman
2009-Nov-26, 12:29 AM
Systematic or a Preferred Frame?

A good start to study where the conventional explanations come up short is the Lammerzahl paper:

Is the physics within the Solar system really understood?
http://arxiv.org/abs/gr-qc/0604052

I am assuming the null result regarding Rosetta flyby is the Nov 13, 2007 flyby. Whether the 2009 flyby is also null has not been reported, AFAIK. A null result would support the model given by Busack:
Simulation of the flyby anomaly by means of an empirical asymmetric gravitational field with definite spatial orientation
http://arxiv.org/abs/0711.2781

After varying three parameters to find the best fit, he used the model to predict that both Rosetta flyby 2 and 3 would give a null result. They happen at the same date, similar to what happened to Galileo I and II. But the dot product on the November 13 date leads to no anomaly, either plus or minus based on the assumptions of the Busack model. The simulation is fairly consistent with the other flybys where the anomaly does occur. The author notes that the premise is contrary to the main tenants of both Special and General Relativity and states that the presence of a flyby anomaly with Rosetta Earth flyby 3 on Nov 13, 2009 will falsify his model.

He uses the CMB frame as the first candidate frame. As a possible check, I am looking to see if the dates where the DAMA/LIBRA signal zeros out between the reported highs and lows going around the sun might correlate with the null result of Rosetta 2 and perhaps Rosetta 3 if the Busack model is supported by observation. The similarity is a frame determined by a supposed WIMP wind from galactic Dark Matter Halo rather than the CMB frame. The frames may be offset from each other, but the events are based on Earth’s motion relative to a frame that moves relatively little over the time the measurements are made, so there may be possible correlation between dates of DAMA/LIBRA quiescence and low flyby anomaly output of the Busack model.

Should the Busack model be supported, he presents us with two doors to go through: one is a preferred frame which is anathema to Relativity which would require a larger theory where GR becomes a special case and the other, which amounts to about the same thing, that space-time has anisotropy.

It should be remembered that our measurements that expose these freefall anomalies do not measure space-time geodesics and mass separately, but rather the product of the two. Anomalies then do not necessarily invoke a problem with Relativity as regards geodesics, but might rather underscore a problem of understanding inertia. If it were the case of gravity behaving badly on certain days of the year on motions below a certain orbit, this would have been monitored by now and further, it would not distinguish between velocities that were hyperbolic and sub-hyperbolic velocities as seems the case with a difference between orbiting spacecraft and the flybys.

Mild mannered
2009-Nov-27, 10:07 AM
Thanks borman
Excellent response - guess that clears that up!
Mild

Mild mannered
2009-Nov-27, 10:10 AM
This seems pretty final
"calculated by computer simulation using an asymmetric field term in addition to the Newtonian gravitational field."

This is the term I should have used in my question to be clearer "asymmetric field"
But I'm glad you understood what I intended - thanks again for the link
Mild

borman
2009-Nov-28, 01:48 AM
It is not all that clear however. The equations used by Busack and and Anderson et al are not derived from conventional physics but are empirical and phenomonal rather than from consistent theory. A computer simulation is more of the phenomenological type rather than coming from established theory. This is noted by the author.

While both the Busack idea and the DAMA/LIBRA signal are both based on a year period, the DAMA signal is thought to be associated with the galactic WIMP wind where max and min relations occur at Dec 2 and June 2, leaving Sept 2 and March 2 as the presumed dates where the effect is minimum. This is an obvious offset from Nov. 13 minimum effect date for the Rosetta flyby 2 and pending announcement of whether or not there was an anomaly for Rosetta flyby 3.

Recall that the frame used by Busack was not the galactic dark matter frame, but the CMB frame. Using the CMB frame also permits coordination with the quadrupole and octupole anomaly also mentioned in Lammerzahl et al as well as the apparent quite serendipitous alignment of the CMB to the ecliptic from the WMAP data. Interpreting this last as the ACW signal also has a possible explanation of a local field or anisotropy. Lammerzahl does suggest understanding the source of either a real anomaly or the source of an undiscovered systematic may be assisted by trying to connect the various anomalies with a common denominator or cause. It would be indeed odd if they all are independent of each other. The secular increase of the AU also noted by Lammerzahl of .15 m/yr discovered in 2004 when our measuring tools became more accurate has probably not yet reached the same status as the other anomalies as there is yet to be ruled out a prosaic explanation regarding the possible impact of systematic calibration errors as suggested by a recent Arakida paper that returned to the issue that rules out the cosmological constant as a source in more detail but essentially reaches the same conclusion as reached in the Lammerzahl paper that it is too small to be considered a source.

borman
2009-Nov-28, 05:01 PM
I think that's one possibility. Of course, we have to remember that experts are studying this, and have tried hard to rule that out. So the fact that it remains as a problem implies that it seems improbably that those effects would be strong enough to create the anomaly.

Interestingly, the latest Rosetta flyby showed no anomaly.

Checking the Rosetta blog does indeed state on Nov 23 that the third flyby showed no anomaly:

Mystery remains: Rosetta fails to observe swingby anomaly

http://webservices.esa.int/blog/post/5/916

Now I shall have to reread the Busack paper more carefully since he predicted this result 2 years ago.