Re: The problem probably wasn't the software...
"Almost certainly not the software although the software migration could be non trivial if the code relied on long deprecated low level run time functions."
Yes, that's why experienced programmers see any kind of dependency as a potential problem. Perhaps it can be hoped for that NASA only employed experienced ones.
"The other factor to consider with the hardware is not just reading the stuff but being able to write it to something your more modern hardware can handle."
Well in that case, that's probably not a problem. VAXes have serial interfaces and even have power of 2 word sizes. Since it can't possibly be a lot of data (probes have very slow links) it should be trivial to just convert it to text, set your terminal program to log the incoming text and just pipe it over that way. It might take a couple of hours, but then again that data obviously was worth that.