As time and habit take the bloom off the rose of space exploration, the messy financial aspects become more and more prominent. When Kennedy announced 40 years ago that the United States would put men on the moon, nobody asked why or how much it would cost. Now those questions are being asked, especially about manned space flight, which is much more difficult and expensive than the unmanned variety and has (arguably, at least-these things, like safety, are hard to measure) yielded proportionately fewer benefits to the earthbound citizens of this world. In the past few decades, a number of ambitious technological initiatives-the American SST, the National AeroSpace Plane, VentureStar-have been shelved in the face of runaway costs, unanticipated technical difficulties and doubts about their real value. Against that background, the Space Shuttle and Concorde are triumphal twin peaks of technological daring and of national pride for their creators; both, however, are discouragingly costly to operate.