Near the end of the Apollo 15 mission, David Scott and fellow moonwalker James Irwin conducted a secret ceremony unsanctioned by NASA: they placed on the lunar soil a small tin figurine called ''The Fallen Astronaut,'' along with a plaque bearing a list of names. This book enriches the saga of mankind's greatest scientific undertaking, Project Apollo, and conveys the human cost of the space race - by telling the stories of those sixteen astronauts and cosmonauts who died reaching for the moon.Many people are aware of the Apollo launch pad disaster in which three men lost their lives, but few know of the other five fallen astronauts whose stories this book tells as well: among them, Ted Freeman and C.C. Williams, who died in the crashes of their 38 jets; the ''Gemini Twins,'' Charlie Bassett and Elliot See, killed when their jet slammed into the building where their Gemini capsule was undergoing final construction; and Ed Givens, whose fatal car crash has until now been obscured by rumors.The extraordinary lives and accomplishments of these and other fallen astronauts - including eight Russian cosmonauts who lost their lives during training - unfold here in intimate and compelling detail, supported by extensive interviews and archival material.Their stories return us to a stirring time in the history of our nation and remind us of the cost of fulfilling our dreams. Colin Burgess is the author of books on space flight, including ''Teacher in Space: Christa McAuliffe'' and the ''Challenger Legacy'' (Nebraska 2000). Kate Doolan was a co-author for ''Australia Post's 1992 International Space Year Book, Mission to Planet Earth''. Bert Vis is a Dutch space analyst who conducts research on the Soviet/CIS Space program. Captain Eugene A. Cernan lives and works in Texas, and is the author of the ''The Last Man on the Moon''.