It's hard to believe that it's been over 50 years since humans have been outside of low earth orbit. It's like we sprinted forward so fast, going from horse drawn carriage to space flight in a generation, only to get frightened and recede back from the highest point, never to go back.<p>Granted there has been an enormous amount of innovation in the last 50 years, but by some accounts we've been going backwards. Humans are no longer capable of mach 3 flight, or making Roman concrete.<p>I think we assume that technology will keep progressing. We assume Moore's law will continue into the future and we forget that there are people behind the progress. The technology that produced those pictures are gone, we might be able to take ones like them again, but never with the same rockets and never with the same photo-chemical processes. Progress is fragile, not inevitable and everything we have can be lost in a generation just as easily as it was made.