In sci.astro Yousuf Khan wrote:
Sounds like he's talking about the Aether Theory without actually
mentioning the Aether here.

Technology Review: Blogs: arXiv blog: The Clue That Could Explain The
Fly-By Anomalies
"Last year, we looked at an idea from Stephen Adler at Princeton
University, that suggested the change in velocity could caused by
collisions between the spacecraft and particles of dark matter. Adler
even calculated the kind of distribution of dark matter particles that
would explain the observed changes in velocity--a kind of halo of them
around Earth. "

No. Adler's papers investigate the possibility that the flyby anomalies
might be caused by drag as spacecraft pass through a cloud of dark
matter gravitationally bound to the Earth. In his most recent preprint
he suggests a specific experimental signature (collisions with dark
matter should slightly heat the spacecraft).

The relevant preprints are arXiv:0903.4879, arXiv:0908.2414, and
arXiv:0910.1564.

Steve Carlip