I noted the thread below entitled "Mysterious force holds back Nasa probe in deep space." For those like myself who have been following the work of Anderson et al. (and others) in this area, you may be interested in the latest version (on the LANL preprint server) of:

Study of the anomalous acceleration of Pioneer 10 and 11
John D. Anderson, Philip A. Laing, Eunice L. Lau, Anthony S. Liu, Michael Martin Nieto, Slava G. Turyshev
Abstract:
http://xxx.lanl.gov/abs/gr-qc/0104064

which offers access to a revised version of their lengthier, earlier preprint, and which has been accepted for publication in the journal Physical Review D. Further, the LANL preprint server contains several preprints in various formats (PDF, PostScript, etc.) of others' work on this topic. Just go to the following URL:

http://xxx.lanl.gov/find/physics

Select Archives->Search all; Years-> All years; in the Abstract field type "Pioneer"; Show-> 100 hits per page; and Do Search. This should bring up a list of almost all of the directly related works (and some peripheral papers as well) in chronological order of posting.

Also, the most recent issue of The Planetary Report (Volume XXI, Number 6, November/December 2001) contains an article by Anderson entitled "The Strange Acceleration of Pioneer 10 and 11."

See http://planetary.org/html/news/articlearchive/headlines/2001/tpr11_12_01toc.html

Alex R. Blackwell
University of Hawaii