Hi Glenn,
OOOps!!
You are quite right, it was Pioneer. There is a mention of this in New
Scientist (www.newscientist.com and click on 'GRAVITY IS BACK').
There is also a reader's letter (Magnetic brake) in the letters section
which has a link back to tht 'This Week' section of 12th september.
(Sorry if you get this twice; it hasn't appeared in my mailbox yet
so I'm not sure if I actuallt sent it or not).
/Gary