At 04:26 PM 9/29/1999 -0400, you wrote:
>Apparently, some believe this is caused by a planetoid's gravity:
>
>
><http://news.bbc.co.uk/hi/english/sci/tech/newsid_460000/460095.stm>http://
>news.bbc.co.uk/hi/english/sci/tech/newsid_460000/460095.stm
>
>Don't know whether there is a consensus about this.
That doesn't make sense to me at all. The paper cited, http://xxx.lanl.gov/ps/gr-qc/9808081 , describes the acceleration as constant in time and directed toward the sun, for three different spacecraft (Pioneer 10,11 & Ulysses) in very different directions. Ulysses was at 1-5 Au and the Pioneers at 20-40 Au. Even if the Ulysses data is a mistake, didn't the Pioneers go off in substantially different directions? And wouldn't a planet's attraction vector vary as a craft moved from 20 to 40 Au?
Robin Hanson rhanson@gmu.edu http://hanson.gmu.edu
Asst. Prof. Economics, George Mason University
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