But the fact that the total NASA investment of $55 billion yielded a paltry $5 billion in true spinoffs, creating entirely new products or industries, suggests a very poor return of ten cents on the dollar. Again, this should not be surprising, given the highly specialized nature of much of the engineering and development work conducted by NASA.

So rather than being an unusually good investment paying 7:1 or 22:1 for each dollar invested, NASA has an astoundingly bad 1:10 payoff -- about a factor of 100 worse than the commercial economy as a whole. (Federation of American Scientists)

Here's a counter-point:

A survey of forty-one companies that reported prior commercial success in transforming NASA R&D investments in the life sciences into marketable goods and services was conducted in late 1997 by the Space Policy Institute, George Washington University. Fifteen of these firms provided useful data for this study. These firms alone have cumulatively contributed over $1.5 billion in value added to the economy over the past twenty-five years. The cumulative NASA R&D investment in the technologies represented by the products of these firms was approximately $64 million. An additional $200 million in private R&D from those companies was stimulated by the NASA investment. This additional R&D was necessary for the production, development, and marketing of the com-mercial products and represents the positive leverage of NASA life sciences investments.

...

NASA's life sciences total expenditures over the past 40 years has amounted to approximately $3.7 billion (which includes many mission related projects that have made it possible for NASA to engage in manned space flight and for which there have been with no expected commercial benefits).

On the basis of these conservative estimates taken with mission success of the life sciences effort and ample evidence of other social benefits from the descriptions provided by the users of many specific life sciences spinoff applications, it can be concluded that NASA Life Sciences investments have more than "paid for themselves." (Space Policy Institute, George Washington University)

Note, though, that this report summary only claims that fifteen companies, which produced a total of $1.5 billion of wealth, received $64 million from NASA. It doesn't say that all $1.5 billion was generated from directly from the $64M, and in fact is does say that doesn't actually say that the $64 million NASA spent during the period studied resulted in the $1.5 billion. It actually implies that $264M in investment led to $1.5B, for a roughly 6:1 return.

Bottom line: after 15 minutes of Googling, I found plenty of NASA bragging and contradictory partial answers (though FAS, which had the negative report, is more neutral and plausible than a space program at a university). To learn more, I would actually have to read stuff and think, which I don't have time for today.