While nothing to do with emulation, I came across this ftp server with all kinds of data from NASA probes.
It’s got all kinds of readings, and even some programs to interpret the data.. (FORTRAN from what I saw). It’s got to be one of the better clearing houses of space probe data available… I suppose later on I’ll see what’s involved in running some of these programs.. But I wouldn’t hold your breath…!
Even for the less inclined, there is jpeg & tiff data!
For example here is a picture from the viking project on Mars:
Stunning to say the least.