Images of Mars-fall:
If we were to cut our defense budget by, say, a third, and instead of using that money for tax cuts we were to put every penny of it into our budget for space exploration, I think it would be better for us, maybe later rather than sooner…but not so much later as we might believe.
If we cut our defense budget by a third, that would barely – just barely – cover the interest on this year's deficit:
2012 defense: $709 billion (1/3 = 236)
2012 deficit: $1,102 billion (without interest)
2012 interest on annual deficit: $225 billion
To put that in perspective? That awesome, awesome Mars rover cost only 2.5 billion, or about 1/100 of just the interest on the deficit.
Data tables from the White House:
http://www.whitehouse.gov/sites/default/files/omb/budget/fy2013/assets/budget.pdf You're looking for "summary tables" S-1 and S-5 for the data above.
I wouldn't be cutting the defense budget solely for reducing the deficit right now. I'd be doing it in order to reinvest the money into something much more likely to bear positive fruit for our future. (And I believe that massive investment in science and technology, as well as our national infrastructure and creating a truly universal health care system, are probably the only ways to guarantee longterm fiscal and economic stability for our nation.)
Just explaining the actual relative size of these things.