NASA spent around $25 billion a calendar year in the early 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 US Department of Defense (DOD), collaborated on thousands of research projects during this period. NASA's research did not focus on the military in all areas. The two agencies instead exchanged information in areas mutually beneficial. NASA's primary focus was on aeronautics, robotics, and other related research. In some cases, NASA subsidized the costs of military research, reimbursing the Air Force only for unique requirements for the flight project.
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. In the last few years, NASA's budget has never exceeded two percent of the federal budget.
The US also has $600 billion in military budget. This budget is almost double the amount of any other country. NASA's budget only represents 4 percent of the total military budget. NASA therefore has only a tiny fraction of the funds available for space exploration.
NASA may not have the resources to build a Mars base. NASA estimates that to place humans on Mars by 2030, it will cost $450 Billion. NASA would be able afford to send a crewed mission to the moon if it had the military budget.