NACA, the predecessor to NASA, began under the auspices of the U.S. Navy, which is Constitutional.
At the time the NACA was eliminated and its assets transferred into the newly created NASA, the Cold War was at a fever pitch. A year earlier in 1957, the Soviets launched Sputnik. And they subsequently reached many, if not most, of the early milestones in space exploration. And had the U.S. continued Apollo to its logical conclusion, any Moon base would most surely be a military installation at some level.
NASA is a quasi-military civilian agency. But even with civilian status, it is an agency dedicated to National Security because outer space can become weaponized (if it has not already). A civilian space agency is not as threatening to other nations as a military space program would be. And because of it's civilian status, not all of its focus need be on discoveries and technologies specific to military applications.
The Constitution is a timeless document. The framers did not need to foresee space travel any more than they had to understand a Boeing 747 as a means of transportation.
I believe an argument could be made that NASA is Constitutional. And if I am wrong, it should be folded into the Pentagon's space program. Most people don't realize the U.S. has two.
private companies are the ones that build weapons, missiles, planes, aircraft carriers, guns, etc. etc.
other nations could care less if the US wastes all of it's money sending rockets into space... if you didn't notice, they are HERE on EARTH, not in space. so if the US wants to launch it's most sophisticated, most expensive, most destructive warhead into space.... all the nations on earth will sit by and watch with glee....
and you're mistaken. most of the research that happens in space will end up having a military application at one point or another...
there is nothing wrong with a civilian space agency. i have no problems with it....
some argue that safety is an issue... the companies aren't going to spend 1 billion dollars building a rocket just so it can explode and kill the astronauts... so that argument is bullshit.... some cite the profit motive as a problem, NASA outsources building of components in space vehicles anyways, so those companies are making a profit, regardless of who's covering the bill, it's 30-40% of costs as profit....
i think making space exploration a civilian thing is going to be very hard not because of the government giving up anything, or safety, or costs, or any of the other bullshit arguments....
it's going to be hard because the US prohibits launching of any rocket with a guidance system, unless it's done by NASA, or other government agencies. a rocket with a guidance system, and the ability to steer is in all essence a missile. space exploration was never about discovering space. it's never been about the 'final frontier', no matter how beautiful Kennedy's speech was.
it's always been about who can launch the biggest missile the farthest, carrying the biggest payload, and getting that where you want it to go, whether it's in space, or here on earth.... the US hasn't been launching scientists into space for the hell of it, it hasn't been for the science. it's a flex of the muscles, to show how we can repeatedly launch big rockets, carrying big payloads, reliably and efficiently..... and the space shuttle is just a front.... that type of vehicle, one that can be launched into space, leave it for a week, then have it return in one piece, and have it land wherever you want it to is one hell of a weapon. it's not a taxi or a 'shuttle' into space....
there's also the national security issue. how would the international community react to there being a sudden increase in launching pads, tests, and overall investment in what's basically a way to launch ICBMs?? i don't think our neighbors will be too happy to see this new arms race begin...