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The Pioneer Anomaly
frankm
post Aug 20 2007, 03:33 PM
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There were several structural problems with the Deen report, three equations did not display and the references were missing. The author has made his report available in pdf form and it includes all of the material.

http://www.glendeen.com/npa2007/Deen_2007_..._10_Anomaly.pdf

The primary reference [1] is available at arxiv.org and it is the 2005 revision. It is a 1.5 mb file.

http://arxiv.org/PS_cache/gr-qc/pdf/0104/0104064v5.pdf
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tfisher
post Nov 22 2007, 03:04 PM
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I just noticed the team working on data recovery put out a new update:
"Pioneer Anomaly: Evaluating Newly Recovered Data".
They still aren't quite to the point of having a calibrated unified dataset -- by the end of the year, they say.
It does sound like their heat modeling project is going pretty well. I'm really hopeful that they will be able
to conclusively answer whether or not thermal forces can explain the anomaly.
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Harder
post Jan 29 2008, 08:45 PM
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Catching up on reading ESO Messenger reports I came across an article in the June 07 edition (#128) in which Newton's law was tested in the low acceleration regime (outer regions-) of globular clusters. The rather astounding conclusion was that globular clusters behave like galaxies in that the velocity pattern in these outer regions flattens off in exactly the same pattern as measured for galaxies.

For this behaviour around galaxies it is widely assumed that large quantities of dark matter (hidden in the galaxies) are responsible. But for globular clusters this explanation is apparently not valid at all. Ergo, it seems that one of the main reasons for "inventing" dark matter in large scale gravity puzzles is no longer valid and that alternatives such as MOND gain a lot of credibility. Especially since it is "unpalatable" as the authors decribe it to assume that dark matter also is a pervasive factor in globular clusters. If someone could explain that to me that would be highly appreciated, but I take the word of the authors until advised otherwise.

A modified Newton law would also go a long way in describing the Pioneer anomaly I believe. This thread will probably remain open for quite some time to come. (Pls support Doug with his new server project smile.gif )

To top it all off, in the Febr08 number of Ciel et Espace there is an article describing a new competitor for MOND, called MOG for Modified Gravity theory. The Pioneer anomaly, which started as a fairly low-key issue, seems on the up again now that Newtons law is shaking, at least in the low acceleration regime. What will be next??

Instead of citing the names of the authors, apologies if I should have done so, here is the link to Messenger #128. Read for yourself!
http://www.eso.org/sci/publications/messen...enger-no128.pdf

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Mongo
post Jan 30 2008, 02:04 AM
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Using globular clusters to test gravity in the weak accelleration regime
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stevesliva
post Mar 31 2011, 05:28 AM
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New work on thermal modeling the affect of IR scattering off of the back of the HGA purports to explain the entirety of the anomaly:
http://www.technologyreview.com/blog/arxiv/26589/
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stevesliva
post Jul 22 2011, 05:39 AM
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And NASA takes another look:
http://www.technologyreview.com/blog/arxiv/27012/

(Links to referenced papers in both this and the last article.)
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Mongo
post Jul 22 2011, 04:23 PM
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From Support for temporally varying behavior of the Pioneer anomaly from the extended Pioneer 10 and 11 Doppler data sets

"The main question is whether or not a statistically significant anomalous acceleration signal still remains in the residuals after the thermal recoil force has been properly accounted for. Results of this meticulous study will be published soon."



Unfortunately, the paper does not appear to give error bars.

Assuming that the error bars are small enough that the above diagram (especially the "Stochastic Acceleration" portion) is reasonably accurate, it looks to me like the acceleration curve flattens out to an asymptotic value of about 7 x 10^-10 ms^-2.

The most obvious cause, in my opinion, would be an exponential decaying acceleration with a half-life of about 3-4 years (declining due to radioactive decay in the RTG?) plus a steady acceleration of unknown origin of about 7 x 10^-10 ms^-2.

Of course I am no expert.
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nprev
post Jul 23 2011, 12:15 AM
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QUOTE (Mongo @ Jul 22 2011, 08:23 AM) *
Of course I am no expert.


rolleyes.gif
smile.gif


--------------------
A few will take this knowledge and use this power of a dream realized as a force for change, an impetus for further discovery to make less ancient dreams real.
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Littlebit
post Oct 5 2011, 03:27 PM
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The name of the game has always been to grow the thermal differentiation to the point that the error bars overlap the known radioactive decay profile; providing a plausible solution.
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gndonald
post May 12 2012, 09:27 AM
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QUOTE (Littlebit @ Oct 5 2011, 11:27 PM) *
The name of the game has always been to grow the thermal differentiation to the point that the error bars overlap the known radioactive decay profile; providing a plausible solution.


Looks like the mystery has been solved...

Pioneer Anomaly Solved: The Planetary Society

I'd also heard that the ESA was considering a mission to probe the effect, but I've not been able to find out much about it.
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Paolo
post May 12 2012, 11:25 AM
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QUOTE (gndonald @ May 12 2012, 11:27 AM) *
I'd also heard that the ESA was considering a mission to probe the effect, but I've not been able to find out much about it.


see for example
A Mission to Explore the Pioneer Anomaly, OSS (Outer Solar System): A fundamental and planetary physics mission to Neptune, Triton and the Kuiper Belt, Odyssey 2 : A mission toward Neptune and Triton to test General Relativity


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I'm one of the most durable and fervent advocates of space exploration, but my take is that we could do it robotically at far less cost and far greater quantity and quality of results.

James Van Allen
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tasp
post May 12 2012, 12:11 PM
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LOL, sounds like UMSFs crack Ice Hunters might get a new gig.

Let's go get 'em a big un !!
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TheAnt
post May 18 2012, 10:03 AM
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Not much reason to send one entire new mission or studies IMO.

The case might be quite closed and filed after JPL have had another look at the matter.

The paper by Francisco, Bertolami and Páramos is found here:
http://arxiv.org/pdf/1103.5222v2
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