http://www.newtonphysics.on.ca/Anoma...eleration.html
This says it's due to dust in the Kuiper belt. Whaddaya think of that?

I say the next probe should bring some Pledge and a dusting rag along to clean up the belt.

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I found this near the end interesting.

So if in a million years Pioneer 11 passes near an alien civilization, they may not know it is artificial and think it is just another pile of rock and dust? So much for worrying about whether some alien will understand the plaque or not.

Kizarvexis

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Uh oh -- how many small comets and asteroids in our solar system are really dust-caked space probes sent out from other star systems?

Yeah It seems that the authors haven't spotted their own little logic problem. If this dust is so adhesive, why is it still there? - we consider that there are possibly billions of bodies in the Kuiper belt, most of them much much larger than the Pioneers. They should all be sweeping up and accreting this magic dust, so there would be precious little left over by now for the probes to undergo this snowball process and turn themselves into interstellar asteroids.

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How was this acceleration detected? I thought Pioneer 10 was no longer functional...

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Heh. Can you imagine if that's what killed off the dinosaurs? A giant asteroid that started life off as an alien probe, and then fell to Earth killing the dinos off. Bummer that.

Nice nod down there at the bottom, John: "The author acknowledges the collaboration of John Kierein for bringing up the IRAS information"

But, I am concerned about the titles on the FAQ page. "Series #8 Why Quantum Mechanics is Non-sense? " for instance, or "Series #14 They burn heretics, don't they?".

I looked into the Series #10: Energy Required to Move a Mass from the Pole to the Equator. Although I didn't wade through the math, it looks like the conclusions were OK. I was concerned because of the blurb on the main page: " It requires external (Earth) energy to move from the equator to the pole..." That is wrong, as Paul's writeup goes to great lengths to show. The surface at the pole and the surface at the equator are in an equilibrium, as the main body of the article states. The entire surface (geoid, or "sealevel") of the Earth is an equipotential surface, in other words.

That's why the water is "flat".

It also neatly explains the relativity phenomenon.

I pointed out the IRAS picture to Paul. It's interesting that the Pioneer drag data may be the only direct measurement of the dust density. I was a little surprised that it hadn't been considered before.

The IRAS picture has always been interesting to me because it dramatically shows that the projection of the plane of the ecliptic crosses the galactic plane right at the center of the galaxy. I've always wondered if there's a gravitational reason for this and if it is true for other planetary systems. Unfortunately, so far as I have been able to find out, there is not yet a way to determine the orbital planes of extrasolar planets.

We also studied the zodiacal light and gegenschein from Skylab. I collected the pictures for this chapter:
http://history.nasa.gov/SP-404/ch3.htm

So does that mean instead of V-ger we will be revisited by P-neer? :P

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I'm not impressed. As far as I can tell, once you remove the "filler", they just assume a density and size of "sand" grains which then magically accounts for the acceleration and then they claim their assumptions as the result!

The "study" makes no reference to changes in acceleration over different time frames. If this idea was correct, there should be no anomalous acceleration except while traversing the Kuniper belt. This is not what has been observed.

The level of analysis here is pretty laughable when compared to the 2002 study (54 pages worth) by Anderson, et. al. And note that the authors still think there is a systematic reason for the acceleration, so they are not arguing for "farfetched hypotheses". http://xxx.lanl.gov/abs/gr-qc/0104064

Here's another interesting article about the anomalous deceleration of the Pioneers.

This article submitted to a journal for review finds the following:

Use asteroids to investigate

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Nope. They will launch a HUGE copper ingot 'bullet' to smash it to bits to see what it is made of.

Nick :wink:

But we do have orbit planes for some binary stars (the Hipparcos catalogues have a doubles and multiples annex with orbital information); I just checked a bunch of them at random and a disproportionate number seem to intersect the plane of the galaxy within 20-30° of the galactic center - Sirius B in particular is almost right-on despite its orbit being tilted on its side with respect to the plane of the galaxy.

Not to hijack the thread or anything ops: but I'd say you may be on to something.

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(I wasn't paying attention and didn't notice at first that you were the OP. #-o )

But having completed a survey of binary stars with known orbit planes, I did find something interesting. I measured the apparent declination of the galactic center (GC) as seen from each star, referenced to the plane of its companion's orbit. I also took into account the obliquity of the orbit to the galactic plane.

If my math is correct (and please do correct me if I've made any errors) then in a perfectly random distribution one would expect a mean obliquity of 90° / sqrt(2), and a mean declination equal to the mean obliquity / sqrt(2).

In fact, I found a mean obliquity of 57.46° which is a little over 90% of the expected figure. So there's a slight tendency for stellar orbits to want to lay flat against the galactic plane. The mean declination of the GC is only 71% of the expected figure, meaning the orbits have a considerably greater tendency to line up to the GC as you describe. Furthermore, when each individual star system's apparent GC declination is divided by its obliquity, the resulting mean is higher - closer to 74%.

The difference between the 71% and 74% figures can be explained if stars whose orbit planes lie closer to the plane of the galaxy have less tendency to line up with the GC than stars whose planes have a high obliquity.

Here is a complete MS Excel spreadsheet of the stars I surveyed and resulting figures.

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Bump.

Questions? Comments? Point out some major error on my part? Anyone?

That survey took me almost 3 weeks. :wink: (Satisfied my own curiosity, at the very least, so it was worth it.)

Planetary Society coverage of the
2005 Pioneer Anomaly Conference
November 6-11, 2005

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