NASA spent approximately $25 billion per year in the 1970s. This was roughly $170 trillion today. NASA's percentage of the federal government budget dropped from 4.5 percent down to less that one percent between 1969-1986.
NASA and the US Department of Defense (DOD), performed thousands of joint research tasks during that time. NASA's research wasn't always military-focused in some areas. The two agencies instead exchanged information in areas mutually beneficial. NASA was mainly focused on aeronautics and robotics research. NASA funded military research sometimes, but only for certain requirements of the flight project, and reimbursed the Air Force.
NASA's contribution to the federal budget increased slightly in 1990s. Under the Bush administration, however that percentage decreased. After that, NASA's portion of the federal budget has steadily declined. NASA's budget is now less than 2 percent of federal budget.
The US has a $600 billion military budget. This is more than any other country's budget for military operations. NASA's budget only represents 4 percent of the total military budget. This leaves NASA with only a fraction of the money that is available for space exploration.
The question is whether NASA will be able to raise the necessary funds to establish a base on Mars. NASA estimates that to place humans on Mars by 2030, it will cost $450 Billion. NASA could afford a crewed trip to the planet if it had the necessary military budget.