It is totally verifiable.
She would have the letter she received in response.
You're right, of course! I've read a couple of articles about this Hillary/NASA thing, and not one of them mentions Hillary producing such a letter.
That in itself doesn't say much. I don't have every letter I received as a kid. But I might have saved something I got from NASA.
As I'm sure you'll agree, it's the pattern here that's important. NASA - Marines - sniper fire, on and on it goes.
Any day now, I expert her to claim that she was a secret adviser to Pope John Paul II.