I think that "Alien" thing is a cover up. I read that the real secret is that with all those exotic fuel mixtures they use in tests, the inevitable spillage poisoned acres of land. Some wag said the EPA would have a conniption fit if they knew about it.
Some years back the Las Vegas Review Journal had a series about workers out there coming to their docs with all these mysterious ailments. The docs were raising Hell because the government refused to say what those people were exposed to, and many of them died ahead of their time because of it.
Shades of far too many of my brothers dying of crap the feral gov denied for years.
Now Gulf vets are going through the same crap.
I vaguely remember something about the burn pits causing health problems in area 51