Manned mission to Mars?

I think the evidence is inconclusive. There is no way to know for sure how many spin-off technologies would have come along later, regardless of NASA's impact, as a result of someone else's R&D. We also don't have any way of knowing what the product timeframes would have been in a world without NASA. There are too many variables for us to know how much real benefit we got directly from the space program. Program proponents and detractors are going to use different assumptions to back up their conclusions.