Is it possible for amateurs/other space agencies with a big enough dish to capture the raw Dawn data themselves as it comes in, or is that stuff encrypted these days?
(I assume outgoing command signals use some sort of authentication scheme, but that seems unnecessary for incoming data.)
Hams have received probe signals before (see the amateur-dsn group on Yahoo) but I'm pretty sure no one has decoded data from any modern probe. They apparently have their reasons for encrypting it through obscurity if nothing else.
Some of our most advanced modulation formats were originally developed for DSN work, in fact. They represent a space-program spinoff that doesn't get the attention it deserves.
(I assume outgoing command signals use some sort of authentication scheme, but that seems unnecessary for incoming data.)