Outer space is a place full of mysteries and there's a long way to go before we can claim to know even one-tenth of it. Since we understand so little, many myths and weird conspiracy theories are bound to emerge as a result.
On the internet you need to be a skeptical reader these days. Claims of aliens and UFOs being discovered or the Moon turning green are the kinds of things that should be checked out carefully.
Even though NASA might know more about such space programs and theories, it is not their responsibility to relay information about such programs. However, being the federal agency at the forefront of exploring outer space, NASA ends up being the front door for all types of wild conspiracy theories.
Space is a pretty fascinating place, but maybe there are things that have happened or are happening in our solar system that we're not supposed to know about? Most shy away from such conspiracy theories, but maybe some theories deserve a second glance...