Medicine? The software that was developed to do image-sharpening on the Hubble pictures turned out to make MRI machines significantly more useful without requiring a change to the hardware.
Social net? NASA has produced a crazy amount of research that would be useful to disaster victims, people in shelters , and assisted living. A couple of examples from the top of my head: safe, stable, long-term storage for high-nutrition meals; long-term emotional impact of environmental factors (colors, scents, etc).
Police: Most forms of wireless communication (including police radios) use SOMETHING that was developed by NASA -- extended-life batteries, transmission protocols, etc.
Even leaving aside the benefits to be head, "$10 billion for NASA" is NOT real money. It's an unnoticeable fraction of the waste in our budgets.
Even if it's as high as 20% that can be re-used, you could get 100% of that value by researching image-sharpening, disaster shelters, food storage, wireless comms and all the other things you mention, directly. So you still have to justify the remaining 80% in other ways, the side-effects already accounted-for.
By the way, in 1997 most Americans thought NASA took about 25% of the budget. Not 0.5%-ish. So when arriving at the decision of what a "lot of money" is, compare it not to what you think but to what most people think and you'll find that NASA is vastly cheaper than the average person's expectations.
As for the 1997 figure, I guess the .5% argument would be useful for the people so horribly uninformed, and you are right that this probably explains why I keep hearing this argument. Fair point.
(Electrical Engineer at NASA)
No, and I advocate against a lot of that spending too. But observing that some other money is spent unwisely doesn't justify spending even more money unwisely on something else. When talking about spending more on NASA, it's pretty much necessary to justify those marginal dollars on their own, not in the context of other government waste.
The other approach can be used to justify essentially any spending, considering how bad the size of our military is for this country. Almost any possible alternate project, including piling up a bunch of money and burning it, would be better than the marginal dollars that get spent on the military.
I do agree that it's worthwhile to correct people's perception of the size of NASA's budget. To be honest, I was quite surprised that it was even 0.5% though.
You seem to be speaking from the vantage of ideology rather than an actual, rational view of reality. Cutting taxes is yet another action (i.e. change from the status quo, like defunding NASA) that you'll need to argue in favor of and outline a plan for. It won't just magically happen even if you cut some budget item.
Looking at the OP, it seems like he was making the former argument, which I buy, so good on him.