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Andrew D
2010-Mar-13, 06:23 PM
Could the pioneer anomaly be a small scale example of the effect that causes higher-than-expected angular velocities of stars in the outer regions of galaxies (dark matter, if you wish)? Both seem to suggest an unnacounted gravitational attraction to the center of the system in question. Are the unaccounted forces proportional?

Also, the wiki article on the anomoly states that the additional acceleration is very close to the product of the speed of light and the hubble constant. Is this significant?

DrRocket
2010-Mar-13, 07:53 PM
Could the pioneer anomaly be a small scale example of the effect that causes higher-than-expected angular velocities of stars in the outer regions of galaxies (dark matter, if you wish)? Both seem to suggest an unnacounted gravitational attraction to the center of the system in question. Are the unaccounted forces proportional?

Also, the wiki article on the anomoly states that the additional acceleration is very close to the product of the speed of light and the hubble constant. Is this significant?


Why not actually read the Wiki article, the whole thing ?


http://en.wikipedia.org/wiki/Pioneer_anomaly

It could be lots or things, or nothing at all.

Andrew D
2010-Mar-13, 08:01 PM
Why not actually read the Wiki article, the whole thing ?


http://en.wikipedia.org/wiki/Pioneer_anomaly

It could be lots or things, or nothing at all.

Yeah... I jumped the gun and asked the question before I read the whole article. After all the suspense and intrigue, the end of the article says "The effect is so small that it could be a statistical anomaly caused by differences in the way data were collected over the lifetime of the probes. Numerous changes were made over this period, including changes in the receiving instruments, reception sites, data recording systems and recording formats."

Oh well.

juggler
2011-Sep-05, 09:55 PM
Roobydo, your original suspicion that there may be a connection between the Pioneer anomaly and the angular velocity of stars in the outer reaches of spiral galaxies may in fact be correct. The following paper that was recently published in Astrophysics and Space Science establishes a connection between the apsidal motion observed in two binary star systems and the Pioneer anomaly. The same effect may also be responsible for the unexplained behavior of stars in the disk regions of spiral galaxies:

http://www.springerlink.com/content/l2328n7528w26202/

I posted this link in another thread regarding the Pioneer anomaly as well.

juggler

Tensor
2011-Sep-06, 01:28 AM
Roobydo, your original suspicion that there may be a connection between the Pioneer anomaly and the angular velocity of stars in the outer reaches of spiral galaxies may in fact be correct. The following paper that was recently published in Astrophysics and Space Science establishes a connection between the apsidal motion observed in two binary star systems and the Pioneer anomaly. The same effect may also be responsible for the unexplained behavior of stars in the disk regions of spiral galaxies:

http://www.springerlink.com/content/l2328n7528w26202/

I posted this link in another thread regarding the Pioneer anomaly as well.

juggler

Do you have a link to the actual paper, without having to go through the process of buying a subscription?

juggler
2011-Sep-06, 02:54 PM
Tensor, I don't. But if you have a local College or University, they will often allow you to use their library facilities as a visitor. Chances are good that they will have an agreement with Springer for access to their papers. If they do, you can simply download the paper by using the Web of Science database, or a similar database through the library.

juggler
2011-Nov-19, 04:14 AM
Tensor, if you still have an interest in reading this paper, I have found a way that you can access it. Enter the following into your Google search bar:

10.1007/s10509-011-0789-4

Click on the first item that is listed. After you click on this link scroll all the way down to the bottom of the page, and click on the DOI link in the lower left hand corner of the page. This should bring you to the journal website.

On the journal webpage scroll down a little until you see the paper, and click on the floppy disk icon that you see near the upper left hand corner of the paper. This will allow you to save the paper to your desktop. If you have any questions, feel free to post them here.

juggler

CJSF
2011-Nov-22, 12:27 PM
http://www.planetary.org/programs/projects/innovative_technologies/pioneer_anomaly/20110722.html


Their work strengthens the case that the source of the anomaly lies in the spacecraft themselves, not in any mysterious outside force acting on them. The most likely cause is heat generated by spacecraft systems, producing a recoil force.

CJSF

AndreH
2011-Nov-24, 01:58 PM
I remember in the German version of the SciAm (called Spektrum der Wissenschaft) someone had an article. I checked the web, but the article itself is not accesible. I only founfd the confirmation that it was in the July issue. As far as I remeber the authors made a simulation of the thermal behaviour of the vehicle and say the recoil force is produced by that (ETA see previous post by CJSF). Only some hand waving here, I try to find the original article. If I can find the journal at home (yes I am still reading printed things;)) I will come back and post what the basic results were.

ETA: I have found the abstract:


17.06.11 | Die altgedienten Raumsonden Pioneer 10 und 11 werden von einer Kraft verlangsamt, über die Wissenschaftler lange gerätselt haben. Nun hat das Spekulieren über eine mögliche "Neue Physik" ein Ende: Die Raumsonden strahlen lediglich ihre Wärme ungleichmäßig ab. »

Translatioin: The old space probe veterans Pioneer 10 and 11 are decalerated by a mysterious force. Scientists have been speculating about the nature of this force for a long time. finally an end has been pt to all speculations about any "New Physics": The space probes radiate the heat generated in an "ungleichmäßig"* way.

*ungleichmäßig can mean: nonuniform (spatial) or not constant (time).

As I said if I find the journal, I will give more details

AndreH
2011-Nov-24, 04:18 PM
Ok, I found another source here: http://wissenschaft.de/wissenschaft/news/313590.html warning it is in German. It is the web page of a more popular German science journal. The guys who did the numerical simulation in May of this year are Benny Rievers and Claus Lämmerzahl. The link says they made a very detailed numerical analysis with a very detailed model of the probe. Getting precise and better results as the simulation from another group in April this year.

Looks as if there are a bunch of people competing to get the best results. I wonder who was the first who had the idea.

ETA: The guys are working at ZARM University of Bremen. I found the project sketch under this link (in English). It is not the final results. http://www.zarm.uni-bremen.de/space-science/fundamental-physics/projects/pioneer/article/cospar-2010-1.html