Pioneer Anomaly Caused by Earth's Rotation?

Thomas, I don't understand the details of your observation posted above-have you asked JPL about this? They have the best equipment to investigate the anomanly and will comment sometimes on stuff like this.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Jim</i>
<br />Thomas, I don't understand the details of your observation posted above-have you asked JPL about this? They have the best equipment to investigate the anomanly and will comment sometimes on stuff like this.
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I am considering to ask JPL about this, but before I bother them, I wanted to check whether there are any obvious flaws with my suggestion. Tom for instance is quite familiar with this topic and could point out any if present.

Thomas

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Thomas</i>
<br />Tom for instance is quite familiar with this topic and could point out any if present.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">I've had my say on this and consider it a waste of time to pursue unless you are especially interested in spacecraft waste heat dumping. See metaresearch.org/home/viewpoint/meta-in-news.asp#Pioneer

Your Earth rotation proposal made no sense to me. Earth's rotation produces a signal modulation with a 24-hour signature, which is already fully taken into account, and in any case cannot emulate a uniform spacecraft acceleration. And your thinking does not even attempt to explain why all spacecraft with power generators on board, but no other spacecraft and no other solar system bodies, are affected. -|Tom|-

No other bodies are effected because they are not excaping from the solar system. Is there any data on other excaping objects? The heat explaination is not all that good. JPL is the way to go.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
I've had my say on this and consider it a waste of time to pursue unless you are especially interested in spacecraft waste heat dumping. See metaresearch.org/home/viewpoint/meta-in-news.asp#Pioneer

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Anderson et al. in their 2002 paper ( arxiv.org/abs/gr-qc/0104064 , p.32) respond actually to the source you are quoting on your page, and they conclude that, taking the actual geometry of the power generators and the spacecraft into account, this would lead to an acceleration of less than 10% of the observed value. Also, one would expect the resultant spin rate change to be strongly correlated with the anomalous acceleration, which it isn't.
From a theoretical point of view, I would anyway not expect that a radiative emission would lead to a resultant force (see the 'Radiation Pressure' entry on my website www.physicsmyths.org.uk/#radpress ).

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
Your Earth rotation proposal made no sense to me. Earth's rotation produces a signal modulation with a 24-hour signature, which is already fully taken into account, and in any case cannot emulate a uniform spacecraft acceleration.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

It can not possibly be fully taken into account as the corresponding physical constants are only known to within a relative error of about 10^-8.
There are in fact unexplained residuals in the data both with an annual and diurnal period (see Figs.17 and 18 in the paper (p.40/41)), but nobody cares about these as it is obvious that they must be due to errors related to the earth's orbit and rotation/orientation. Basically all sinusoidal residuals are being ignored. The point is here that the acceleration due to the earth's rotation will not appear as fully sinusoidal as the data will only show the parts of the cycle where the acceleration is directed away from the space craft (during the other half, the ground station is on the reverse side of the earth). So if averaged over many positions, there will be an apparent net force towards the earth if the mentioned inaccuracy of 3*10^-8 is such that the model value is too small by this amount.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
And your thinking does not even attempt to explain why all spacecraft with power generators on board, but no other spacecraft and no other solar system bodies, are affected.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

The points I mentioned above besides, the data from other space craft like Voyager for instance are simply not accurate enough to show the effect (due to the lack of spin stabilization; see www.planetary.org/programs/projects/inno...ly/anomaly_data.html ).
On the other hand, for objects within 10 AU or so, modelling errors due to other physical effects can be expected to mask such a relatively small anomaly.

Thomas

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by Thomas</i>
<br />Anderson et al. in their 2002 paper ( arxiv.org/abs/gr-qc/0104064 , p.32) respond actually to the source you are quoting on your page, and they conclude that, taking the actual geometry of the power generators and the spacecraft into account, this would lead to an acceleration of less than 10% of the observed value.

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This article is considered somewhat of a classic "save-the-hypothesis" and "wipe-egg-off-face" paper. It infuriated other knowledgable people at JPL. Miles Standish (JPL's leading celestial mechanician), for example, won't even speak to Anderson anymore because he is so disgusted with John's incessant efforts to keep this topic alive and funded. At this point, the matter is still of interest to anomaly hunters, those who know little or no dynamics, and those who have a pet theory that can "easily explain" the anomaly; but almost everyone else has closed the book on the "Pioneer anomaly".

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Also, one would expect the resultant spin rate change to be strongly correlated with the anomalous acceleration, which it isn't.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">That is a false claim, one of many intended to cast doubt on the obvious explanation for the anomaly. The spacecraft spin is around the Pioneer-Sun line, so it doesn't matter how fast or slow the spacecraft is spinning. The waste heat excess directed along the Sun line will be unchanged by spin or non-spin around that axis. Only a spin that could interrupt the communications to Earth could interrupt the waste heat dump in the same direction.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">the data from other space craft like Voyager for instance are simply not accurate enough to show the effect (due to the lack of spin stabilization)<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">Another false claim. Spin stabilization is irrelevant unless the anomaly is generated within the spacecraft. Then (as for Voyagers, also on escape trajectories) the anomaly should vanish. And it does. Now there are numerous non-escaping spacecraft, and only the one with a similar heat generator on board (Ulysses, near Jupiter) shows roughly the same anomaly.

We all have to judge which anomalies to spend our time on, and which "experts" to trust when we can't check things out for ourselves. I've made my choices. Good luck with yours. -|Tom|-