Joe Jakarta wrote:
http://www.sciam.com/article.cfm?art...4583414B7F0000

"One of the most intriguing mysteries in physics is the "Pioneer
anomaly," the slowing down of two spacecraft by an unknown force. NASA
launched Pioneer 10 and 11 in 1972 and 1973, respectively, and the
craft returned stunning images of Jupiter and Saturn. But as both
spacecraft continued their voyages at speeds of roughly 27,000 miles
per hour, astronomer John Anderson of the Jet Propulsion Laboratory in
Pasadena, Calif., noticed anomalies in telemetry data dating from as
far back as 1980. With continued analysis, researchers determined that
the spacecraft had been slowing down at a constant rate: each year they
fell 8,000 miles short of their calculated positions. The strange
behavior sparked several theories, but the lack of data made culling
the ideas difficult. Now a proposal to analyze telemetry from the early
years could literally point toward the correct explanation.

"The most obvious theory was that something on the spacecraft
themselves created a braking force--leaking gas or heat radiation,
perhaps. Over the years, however, researchers increasingly viewed this
hypothesis as less likely, and some physicists began to explore
possible flaws in Newton's laws and relativity. Others posited that
dark matter was the culprit: it might exert a gravitational or drag
force. A third theory embraces the idea that a minute acceleration
exists in the velocity of light, which might result in the appearance
that the probes are slowing down: if light travels faster, telemetry
signals arrive faster, and the craft seem to be closer.

"Anderson and theorist Michael M. Nieto of Los Alamos National
Laboratory have proposed a way to filter the ideas, noting the
interesting fact that the direction of the anomalous force would be
different for each theory. If the force points toward the sun, then it
should be a gravitational effect. If it points toward Earth, it should
be an anomaly relating to the velocity of light. If it points in the
direction of motion, it should be a drag force or a modification of
inertia. And finally, if it points along the spin axis of the probes,
it should indicate a force generated by the craft. ..."

(Alexander Hellemans, "A Force to Reckon With: What applied the brakes
on Pioneer 10 and 11? ", Scientific American, 10 October 1995)


Where's *your* money, ladies and gentlemen?


Ill Take an unobserved gravitational influence on the craft for 1000
Alex.....

Ill be honest, my math skills stop with alegbra and I have a feeling
that my skills are no match for the scope of what Im about to
postilate, however, someone with better skills then myself should be
able to crunch the numbers.

Here are the facts as I understand them:

1. Probe traveling at 27,000 miles per hour

2. John Anderson of the Jet Propulsion Laboratory in
Pasadena, Calif., noticed anomalies in telemetry data dating from
as
far back as 1980.

3. Probe falls 8000 miles short as to where it is supposed to be

The only other time Ive seen scientist question there calculations on
this level was when Uranus was not where it was supposed to be. We all
know how that turned out. Is it possible that there could be an
unobeserved planet or maybe even something smaller like a kuiper belt
object that could have "peturbed" its tragectory? Nothing as big as a
Star, not this close to Sol, but something non the less.

The problem is, if it is another planet or moon or whatever, then I
would imagine that the probe would have been more then just slowed
down. I would think a curve, even if its only a slight one would be
applied to its tragectory throwing the probe WAY off its preconcived
course. Even if the probe approched the anomoly "head on" and just
missed it, I would think that it course would still be slightly
deflected.

So what does that leave us with?

Well, one common source for slowing things down is friction. Theres not
a hell of a lot of stuff in the spaces in between planets, but could
the probe have passed through a dust cloud that we cannot detect from
here? Dust could cause friction that could slow it down.

I also thought that perhaps the solar wind itself is deflecting of the
heliosheath and catching the solar panels and acting like an "air
brake", but I would think that the two voyagers would have detected and
experianced the same speed changes. Although, Pioneer 11 is on a more
direct approched to the "bow shock". Perhaps an outside influence
pentrated the bow shock and is slowing it down.


Star