Why doesn't the government give more money to NASA?

I mean think about it, the Army gets about 700 billion dollars a year, NASA gets about 7 billion, if you took 200 billion dollars away from the Army, we would still have the best equipped army, and if you give that to NASA, we would also have the best space exploration system! Also, space exploration could help our economy, if we could mine a nearby asteroid of medium size, there would be enough money to give every body in America, 500 dollars! Think about that, you politicians.