[Steely Tom]

I read an article a few years ago that the knowledge to maintain or rebuild some missiles is lost because the people who made them and maintained them retired and died and did not impart that knowledge to a new generation so making a space manned vehicle would mean having to re-learn things known in the 60s and 70s.

Yeah, but they were able to figure it out in the first place in just a few years.

Besides, today's materials were not around back then.

I read a couple of weeks ago where Elon Musk's company is manufacturing rocket engines using 3-D printing. All the other big booster companies are jumping on the same bandwagon. ATK, ULA, etc.

[Trumpinator]

I have used 3D printing. I can’t imagine anything produced from that would be able to stand the rigors of launch and the vacuum of space. What material are they using? Some super epoxy I imagine. Wow if true.

[Trumpinator]

PS: I want to add I don’t think this ancient proto civilization was traveling into space, etc. I think they were an advanced stone age civilization. No bronze or iron has been found earlier than the proposed dated - if they knew how to work iron and bronze the evidence would have long since been gone even by the time Sumeria rose up.