During the early 1970s, NASA spent about $25 billion a year. This is roughly equivalent to $170 billion today. NASA's percentage of the federal government budget dropped from 4.5 percent down to less that one percent between 1969-1986.
During that period, NASA and the US Department of Defense (DOD) performed thousands of research tasks together. NASA's research is not always focused on military issues in certain areas. Instead, the agencies shared information in areas of mutual concern. NASA was focused mainly on aeronautics-related research. NASA paid for military research costs in some cases. The Air Force was only reimbursed for specific requirements.
During the 1990s, NASA's portion of the federal budget increased slightly. This amount fell again under the Bush administration. NASA's percentage of the federal budget steadily decreased after that. NASA's budget is now less than 2 percent of federal budget.
The US also has $600 billion in military budget. This budget is nearly double that of any other country. NASA's budget, however, is just 4 percent of that of the military budget. NASA is left with only a fraction the money available to space exploration.
It is not clear whether NASA will have enough money to build a Mars base. NASA estimates that to place humans on Mars by 2030, it will cost $450 Billion. NASA could pay for a crewed space mission to the planet if they had the military budget.