I was listening to a NASA podcast today - a NASA team has repaired a tape drive that's been sitting in a barn for 16 years, and used it to restore / digitise tapes from luner orbiters. They talked how originally some of the footage of earth (from the moon) was so blurry you couldn't make out practically any detail, but with modern processing techniques they can now clean them up to reveal detail larger than 5km. I guess that this wouldn't be of interest to photographers though, who seem to need in excess (literally!) of TWO HUNDRED potential tone changes in every single square MILLIMETER to be happy. From 250,000 km, I bet even 5km "artifacts" look sharp.