My Max Persistent Debris is set to unlimited and it had a PPD12 Cupola Module. Is that sufficient for command pod or probe core? I would assume so, but I could be wrong! Then again, I launched the same rover prior and had it crash on landing. It's still there! So I think that at least answers that question. Some of the boosters I used to launch the thing still appear in my debris, but the rover is not there. Not that I really care, it was my first rover and drove like junk. It would likely have been replaced with a more functional vehicle in the near future. I would just like to know that future items will not vanish after time designing, launching, landing and so on…