celestia and JPL license
Some time ago I adopted the celestia package. The package contains textures
which seem not to be DFSG free. (see bug #174456).
It looks like the main problem is the NASA's JPL license. I have two
options now: Either I replace those textures by DFSG-free ones, or I move
the package to non-free. I'm trying to find suitable textures for the first
option, but unfortunately, I don't understand what makes the JPL policy
I have to know this because I don't want to replace non-free textures with
new textures which are non-free as well.