Henry Spencer wrote:

In article ,
Derek Lyons wrote:


... (There are a couple of unanswered questions about design
principles and details IIRC. No showstoppers, but contrary to the
handwaving of bombardmentfarce, we can't build one from a standing
start - a non trivial amount of development must be done first.)



No question about that. Outside reviewers consistently thought the Orion
enthusiasts were being seriously optimistic about schedule and budget,
with a lot of optimism about incompletely-solved problems.


Here's something _very_ interesting from that Orion .pdf that Rusty found:
http://ntrs.nasa.gov/archive/nasa/ca...1977085619.pdf
If you go over to page 134 of the report (pdf page 146) you will run
into LENS (Low Energy Nuclear Source); a very low yield nuclear device
that will is to be detonated near the pusher plate to check out how it
behaves...nothing unusual in that...except that LENS is a....ready for
this? "the LENS system, which is a very-low-yield "gun-type" plutonium
assembly (see Fig. 7. 10)."
You heard it here first- a gun assembly nuclear device employing
plutonium, not uranium, as its fissile material.
That was supposed to be impossible due to a unstable isotope of
plutonium (Pu-240) that would cause it to pre-react if gun assembly was
used, and which was supposed to not be separable from the Pu-239.
Well, either the Orion team made a major slip in their report, or by
1964 we knew how to separate Pu-239 and Pu-240.

Pat