During the early 1970s, NASA spent about $25 billion a year. This was equivalent to roughly $170billion today. NASA's contribution to the federal budget decreased from about 4.5 percent to under one percent between 1969-86.
NASA and US Department of Defense (DOD), collaborated on thousands of research projects during this period. However, in some areas, NASA's research was not particularly military-focused. Instead, the two agencies exchanged information in areas of mutual interest. NASA primarily focused on robotic and aeronautics research. NASA sometimes subsidized military research and reimbursed the Air Force for special requirements specific to the flight project.
NASA's part of the federal budget rose slightly during the 1990s. This amount fell again under the Bush administration. After that, NASA's portion of the federal budget has steadily declined. NASA's budget was less than 2% of the federal government budget for the past few years.
The US has a $600 billion military budget. This is nearly twice as much as any other country's military budget. NASA's budget, however, is just 4 percent of that of the military budget. NASA therefore has only a tiny fraction of the funds available for space exploration.
The question is whether NASA will be able to raise the necessary funds to establish a base on Mars. NASA currently estimates that it will cost $450 million to land humans on Mars by 2030. If NASA had the military budget, it would be able to afford a crewed mission to the planet.