That's what I thought. I can't imagine that
NASA would consign
mission data to the dumpster, particularly given the (comparatively)
small number of missions.
40 years ago, when I was working at the National Space Sciences Data
Center (building 26, Goddard Space Flight Center), tapes, decks of cards,
and Fortran source were going missing on a regular basis, and some of the
people managing the tape collections felt that only the most recent data
was worth keeping. On a few occasions, I was handed "scratch" tapes to
use for output and transfer to plotters that had important sounding prior
labels on them. "I'm sure that there must be a few more copies of that
data around somewhere."