JAMES OBERG and BUZZ ALDRIN have been collaborating on orbital strategies for Mars exploration since they met at the first "Case for Mars" conference in Boulder, Colo., in 1981. Oberg, an aerospace writer and consultant, was an engineer at the NASA Johnson Space Center in Houston from 1975 to 1997. Aldrin, who was the second man to walk on the moon, retired from NASA's astronaut corps in 1970 to return to the U.S. Air Force, where he commanded the test-pilot school at Edwards Air Force Base. He is now an aerospace consultant based in Laguna Beach, Calif.
