NASA engineers did not understand the popular enthusiasm aroused by Apollo. They thought the Giant Leap for Mankind was not the lunar landing itself, but the technological prowess it displayed.

This led to the mistaken inference that the way to maintain popular support, and hence generous funding, was to propose megaprojects of great technical complexity, regardless of whether they were intrinsically interesting.

They are surprised and disappointed that the public are unimpressed by the shuttle and ISS, despite their technical virtuosity. The Giant Leap delusion persists today, in the form of proposals for a flags-and-footprints mission to Mars.

In reality, of course, Apollo existed because Jack Kennedy and Nikita Khruschev chose to make space a principal arena for competition between the superpowers. The purposes of the program were to overcome the perceived Soviet lead in space, and to foreclose the possibility that the USSR would reach the Moon first and claim it as Soviet territory. No Congress was willing to spend more than the minimum needed to achieve those objectives.

The Outer Space Treaty of 1967 relieved concerns about Soviet hegemony by banning weapons and territorial claims on the Moon. This allowed Congress to respond to Lyndon Johnson's simultaneous expansion of social programs and the war in VietNam by slashing funding for NASA. As shown in Figure 1, the budget peaked in 1966, and then fell precipitously.

Despite these obvious trends, NASA developed grandiose visions of the post-Apollo program, which culminated in the Space Task Group Report of 1969. (3)

The STG proposed three options. The most ambitious called for

• a reusable Earth-to-orbit shuttle and a small space station by 1975;
• a reusable orbit-to-orbit tug and a lunar orbit station in 1976;
• a nuclear-powered tug and a lunar surface base in 1978;
• a 50-man space base in Earth orbit in 1980;
• a manned Mars mission in 1981;
• and expansion of the Earth orbit space base to 100 people by 1985.

The other options retained all these objectives, but reduced the cash flow by delaying some of them for up to five years.

Figure 1 also shows the funding profiles required by the STG proposals (in 2003 dollars). Richard Nixon responded immediately, making it perfectly clear that the whole STG Report was sheer fantasy, and that NASA should expect less money, not more.

Given this fiscal reality, NASA could have adopted an incremental approach to space development. The obvious plan was to launch the second Skylab, with minor modifications to permit a long life on orbit, and to support it initially with a simple ballistic capsule (such as a proposed stretch of the Gemini capsule, called the Big G, which could carry seven to nine people) atop an expendable booster.

In time, a small reusable orbiter would replace the capsule, and the booster could eventually become reusable too. Beyond that, the scope of the program would depend on funding, but might include a permanent lunar base.

This plan was unacceptable because it had two dreadful defects. First, it involved a series of small, affordable steps, instead of the Giant Leaps that many in NASA thought essential to public support.

The second and much worse problem was that Skylab was a project run by Marshall Spaceflight Center in Huntsville, Alabama, and not by JSC. As JSC Deputy Director Chris Kraft said, people in Houston believed that "being in charge of manned spaceflight was their birthright," and they resented Marshall's intrusion.

Kraft once told me that a space station was unnecessary, because the shuttle would be so cheap that astronauts could commute to orbit, returning home every evening.

The claim that the shuttle would be cheap was based on an economic model that was totally divorced from reality. It assumed that the shuttle would fly 60 times per year, so that fixed costs could be amortized over many missions, and that the direct operating cost would amount to less than $250/pound (2003 dollars). If these estimates had proven correct, we would have flown the shuttle 1500 times by now (and presumably would have killed about 200 astronauts).

The worst mistake made by NASA managers was that they allowed disputes over who would be in charge to influence the direction of the program. Their preoccupation with intercenter turf wars obscured the writing on the wall.

The real lesson of the STG debacle was that a healthy program was not sustainable if funded only by taxpayers. NASA could retain exclusive control of an insignificant, moribund program, or it could accept a supporting role in a growing program, funded by investors and controlled by entrepreneurs.

Given these options, NASA chose the first - but instead of doing the best it could with limited funds, it dissipated its resources in the care and feeding of the white elephants called shuttle and ISS.