The Pioneer Anomaly

What is it? What do you think it is.

Personally I think it is a nothing more than the fact that we are pushing the limits of technology.

www.ph.unimelb.edu.au...

physicsweb.org...

en.wikipedia.org...

I think the wikepedia article gives several possible explanations that sould good to me.

# observational errors, including measurement and computational errors, in deriving the acceleration

* Approximation/statistical errors

# a real deceleration:

* by gravitational forces from unidentified sources such as the Kuiper belt or dark matter
* drag from the interplanetary medium, including dust, solar wind and cosmic rays
* gas leaks, including fission-produced helium escaping from in the spacecrafts' radioisotope thermoelectric generators
* radiation pressure of sunlight, the spacecraft's radio transmissions, or thermal radiation pressure from the RTGs
* electromagnetic forces due to an electric charge on the spacecraft
en.wikipedia.org

mod edit to use "ex" instead of "quote"
Posting work written by others. **ALL MEMBERS READ**
Quote Reference.

[edit on 14-1-2006 by sanctum]

* by gravitational forces from unidentified sources such as the Kuiper belt or dark matter

Possible but purely speculation at this point.

* drag from the interplanetary medium, including dust, solar wind and cosmic rays

Unlikely for this scale of the anomoly(this is what I've read before)

* gas leaks, including fission-produced helium escaping from in the spacecrafts' radioisotope thermoelectric generators

This was ruled out I think.

* radiation pressure of sunlight, the spacecraft's radio transmissions, or thermal radiation pressure from the RTGs

I'm having a bit of trouble swallowing this.

* electromagnetic forces due to an electric charge on the spacecraft

Ditto.

All IMHO of course.

Without resorting to the wiki...

I will just shoot this out there... but what if space wasn't a complete vacuum?

what if there were areas (gaseous pockets) that allowed simple gravity or even friction to occur to slow these down?

It has always confused me regarding these gaseous clouds that we see great pics of with Hubble...
but why are they not dispersed as fast as they form, as they would in an absolute vacuum...

space rules seem to allow for such fudge facts..

Nebula, or those dust clouds Hubble takes pictures, are massive. They are typically larger than our entire solar system, often multiple times so.

There's no doubt they'd impact anything traveling through them; they're composed of matter that has mass. The gravitational effects would be negligible to anything traveling through them, but most planetary nebulas have a gravity well, such as a star, at their center which both holds them in place longer than would normally happen without any forces impacting it in space.

Might be modified gravity too! There're lots of ideas floating about. Increasingly papers are commenting on the relevance of the Pioneer anomaly to theories which may produce some departure from Newtonian gravity (where Newtonian gravity would be otherwise expected to be ok).

This sort of thing might be a good candidate:

www.arxiv.org...

arxiv.org...

An actual paper considering a 'modified gravity' explanation for the anomaly:

arxiv.org...

A paper attempting a relativistic formulation of MOND which also has something to say about the anomaly:

arxiv.org...





[edit on 14-1-2006 by Greenglow]

"I will just shoot this out there... but what if space wasn't a complete vacuum? " == LazarusTheLong

I am inclined to agree with you, but add some supporting thoughts. Bear in mind that deriving the
Pioneer Anomaly has some immediately questionable fascets. While interesting, lets look to the measurement itself.
Using
www.answers.com...
Precision
1. The ability of a measurement to be consistently reproduced.
2. The number of significant digits to which a value has been reliably measured.
Accuracy
The ability of a measurement to match the actual value of the quantity being measured.

Accuracy and Precision are not the same thing and should not be confused. The precision of the Pioneer measurement
involves two measurements, 10 and 11. Statistically, even a "Student T" requires a minimum of five samples. I conclude
this is not a precise measurement.
From HowardRoarks references, it would seem that the very small deceleration would be the accuracy of the measurement
compared to the known deceleration of the solar system acting on the vehicles. What is left out is just how accurate this was
expected to be using the measurement techniques in play. Since it is called an anomaly, we must ourselves infer that their
measurement was expected to be far more accurate than it is. Thus the anomaly is that we see deceleration over and above what was
expected from the accuracy of the measurement while the precision of the measurement, although supporting an anomaly conclusion, does no
more than that.

Lets say the error was the other way, that the crafts appeared to be accelerating instead of being in drag. I doubt you would have
heard about it as an examination of computational error sources would be more of a suspect. But this way, it sorta lends support
to some way out concepts like dark matter, etc, so its news just in case we have found a way to measure that stuff. But if it turns
out to be a reliable indicator, far more mundane explanations should be examined first.

The July 2005 issue of Discover presents an interesting article on NASA's new toy, the Spitzer IR Telescope, titled "How to build a Planet".
The article notes that one of the early targets, a star near us called Vega (And very very bright) still has a planetary dust disk, which should
have blown away already, given the intense solar radiation of Vega. It has NOT. Now planetary building theories must be revisited to try
to explain how this can be.

And so, just for you, LazarusTheLong, the short conclusion is that the key statement from Howard's first reference appears to be in doubt
beyond the areas swept out by our inner planetary system.

Possible wrong key statement:
"For example, ordinary gas and dust cannot explain it because there are rather stringent constraints on the density of
ordinary matter in our solar system coming from its interactions with the sun's light. "

(At least until Spitzer opened its eyes that is.)

Originally posted by HowardRoark

Personally I think it is a nothing more than the fact that we are pushing the limits of technology.

Or maybe we're pushing the limits of conventional physics? It's such a slight shift occuring over such vast distances that it's virtually impossible to recreate in the lab and doesn't provide for a lot of observation.

Interestingly enough, Paul Laviolette predicted this type of photon blueshifting to occur and had proposed a test to see if it happens.

The novel physics methodology of subquantum kinetics predicted in 1979 that photons should blueshift their frequency at a rate that varies directly with negative gravitational potential, the rate of blueshifting for photons traveling between Earth and Jupiter having been estimated to average approximately 1.3±0.65 X 10^-18 s^-1, or 1.1±0.6 X 10^-18 s^-1 for signals traveling a roundtrip distance of 65 AU through the outer solar system. A proposal was made in 1980 to test this blueshifting effect by transponding a maser signal over a 10 AU round-trip distance between two spacecraft. This prediction has more recently been corroborated by observations of maser signals transponded to the Pioneer 10 spacecraft.

www.etheric.com/Downloads/pioneer.html

His prediction of it (which was shown to be accurate to within two standard deviations) came from his theory of subquantum kinetics.

Subquantum kinetics is a novel microphysics paradigm that incorporates concepts developed in the fields of system theory and nonequilibrium thermodynamics. One of its distinctive features is that it begins at the subquantum level for its point of departure.

www.etheric.com/

He tried to post it on arxiv.org and got his posting priveleges revoked

The first time that LaViolette contacted scientists at JPL was in 1980. At that time he told them that his theory predicted that a blueshifting effect should be observed in spacecraft maser signal transmissions and told them the amount of blueshifting that could be expected. John Anderson, who spearheaded this work at JPL was part of the same group of researchers with whom LaViolette had spoken. After that Anderson began to notice the effect in the Pioneer 10 data and finally in 1992 he decided to initiate a formal study of the data.

www.etheric.com/physarchive/suppression.html

So, is it a leaky gurnsten valve or does the emporer (conventional physics)
have no clothes?