Forty years ago, I wrote an article for Technology Review titled "Shall We Build the Space Shuttle?" Now, with the 135^th and final flight of the shuttle at hand, and the benefit of hindsight, it seems appropriate to ask a slightly different question—"Should We Have Built the Space Shuttle?"

After the very expensive Apollo effort, a low-cost space transportation system for both humans and cargo was seen as key to the future of the U.S. space program in the 1980s and beyond. So developing some form of new space launch system made sense as the major NASA effort for the 1970s, presuming the United States was committed to continuing space leadership. But it was probably a mistake to develop this particular space shuttle design, and then to build the future U.S. space program around it.

The selection in 1972 of an ambitious and technologically challenging shuttle design resulted in the most complex machine ever built. Rather than lowering the costs of access to space and making it routine, the space shuttle turned out to be an experimental vehicle with multiple inherent risks, requiring extreme care and high costs to operate safely. Other, simpler designs were considered in 1971 in the run-up to President Nixon's final decision; in retrospect, taking a more evolutionary approach by developing one of them instead would probably have been a better choice.

The shuttle does, of course, leave behind a record of significant achievements. It is a remarkably capable vehicle. It has carried a variety of satellites and spacecraft to low-Earth orbit. It serviced satellites in orbit, most notably during the five missions to the Hubble Space Telescope. On a few flights, the shuttle carried in its payload bay a small pressurized laboratory, called Spacelab, which provided research facilities for a variety of experiments. That laboratory was a European contribution to the space shuttle program. With Spacelab and the Canadian-provided robotic arm used to grab and maneuver payloads, the shuttle set the precedent for intimate international cooperation in human spaceflight. The shuttle kept American and allied astronauts flying in space and opened up the spaceflight experience to scientists and engineers, not just test pilots. The space shuttle was a source of considerable pride for the United States; images of a shuttle launch are iconic elements of American accomplishment and technological leadership.