Challenger accidentScienceFixing the NASA Piloted Program After Challenger: Views from 1989 and 1993 (plus an alternate history addendum)By David S F PortreeScienceA Stronger, Safer, Better Space Shuttle (1982)By David S F PortreeScienceJPL/JSC Mars Sample Return Study II (1986)By David S F PortreeScienceCollins Task Force Says Aim for Mars (1987)By David S F PortreeScienceShuttle With Aft Cargo Carrier (1982)By David S F Portree
