(Spud) wrote in message ...

Is there enough information to state the acceleration is directly towards the sun ?
What if there is an acceleration towards the earth ?

From the article of John D. Anderson et al
http://www.arxiv.org/abs/gr-qc/0104064
explaining the details of the anomaly observed in the Pioneers 10 and
11, "I understand" that the available information is not enough
precise to discriminate if the supposed acceleration is towards the
Sun or towards the Earth. More precisely, since they also detect
annual and diurnal variations in the effect that they suspect are due
to:

Quotes
"...modeling errors in the Earth's ephemeris, the orientation of the
Earth's spin axis (precession and nutation), or in the station
coordinates (polar motion and length of day variations), the
least-squares process (which determines best-fit values of the three
direction cosines) will leave small diurnal and annual components in
the Doppler residuals..." ...

"...We conclude that for both Pioneer 10 and 11, there are small
periodic errors in solar system modeling that are largely masked by
maneuvers and by the overall plasma noise. But because these sinusoids
are essentially uncorrelated with the constant aP , they do not
present important sources of systematic error. The characteristic
signature of aP is a linear drift in the Doppler, not annual/diurnal
signatures..."
/Quotes

my interpretation is that the authors believe that it is impossible to
elucidate your question under the present circumstances.

Isn't this worth investigating.

It would be interesting to investigate but I don't think the available
data of the Pioneers 10 and 11 are precise enough to extract such
information.

But actually I don't even believe that the observed anomalous
acceleration is real but only apparent as I tried to explain in
another thread some time ago.
Although I am aware that there are many authors that claim to have
explained the anomaly using orthodox Physics I nevertheless ask again
for comments to my non-orthodox explanation that received no comments
when I posted it (except the typical barking from Uncle Al that I
always ignore). This is the URL:

oogle.com

Spud

Best regards
Carlos L.