Originally Posted by
pasta
........why would another program from the same era, that was also retired due to cost/obsolescence, and who's successor is very much in the public domain, still be under wraps?
You have made several references to the X-37 being a "successor" to some type of Aurora program, but perhaps it is not. A just in time air launch for transonic/suborbital recce or strike is a different profile to a spacecraft that spends months or years in orbit. As for the "very much in the public domain", I note that many specifics of the X-37 flights are quite vague, only citing "spectacular success", without saying what they actually did.
As for some programs being declassified and in museums and others not, there can be a whole variety of reasons for that. I do not believe we know all about every past program, whether they were successful or not, nor should we.