There is another major misconception that NASA has more actively spread, perhaps because many in the agency have convinced themselves that it is really true. Here it is: the primary goal of the Space Shuttle is the advancement of scientific knowledge. Most scientists roll their eyes when they hear this claim.

Don't misinterpret what I say: there is good, even great science launched into space on the Shuttle. Results from the Hubble Space Telescope excite physicists and astronomers as much as the general public.  But a case can be made that Hubble could have been launched at a lower cost by non-reusable rockets. The United States military prefer to launch their spy satellites-close cousins of the space telescopes-with unmanned vehicles. Such satellites don't have to be man-qualified, that is, they don't require the extra engineering costs to make them absolutely safe to be in space alongside humans.

True, Hubble was defective, and required repair by Shuttle astronauts. But the military loses its spy telescopes too, and its response is to launch a replacement. Launching two completely new Hubble telescopes--the original and a replacement, with neither qualified for human servicing (and therefore cheaper)-- would arguably have been less expensive in the long run.

When it comes to the science itself, the Space Shuttle is a poor choice of platforms. Humans are a source of noise-vibrational, infrared, gravitational. Sensitive experiments must get away from this. Just flying an experiment on a manned mission automatically raises the experiment's costs. Many scientists moan privately about scientific missions that were delayed and made more costly because they were moved off unmanned launch vehicles and forced to become part of NASA's scientific justification for the Shuttle.

Hubble aside, what would you name as the really glorious achievements of NASA in the last 20 years? My favorite: the discovery that every moon of every planet is significantly different from every other moon, a result completely unanticipated and still not understood. One might also pick the amazing success of weather satellites. Or the remarkable pictures you get from your satellite TV system. Those in the know might pick our space spy systems. Then there's GPS-the Global Positioning System, used to guide airplanes, boats, hikers, automobiles as well as soldiers and smart weapons. These projects have one thing in common: they were all unmanned.