Lunascaping and Zubrin

BTW I looked at Zubrin's _Entering Space_ in the bookstore today. Had some
interesting stuff -- I'm now more confident of an Orion Drive being able to
hit tenth-lightspeed (esp. as he's not a big Orion fan.) He dismisses
O'Neill's ideas cavalierly, though; I didn't read carefully, but it seemed
like he pulled rebuttal cost figures out of his butt, whereas his own ideas
got detailed calculation. That was my take on it too. To see what I have to say on this subject, go to http://members.aol.com/oscarcombs/spacsetl.htm#zubrin I also pick on Zubrin a little here: http://members.aol.com/oscarcombs/case_spc.htm#Robert_Zubrin