Possibilities are a recruiter
something you put in for some time ago that just happens to match the job listing you found here
??
This position title of Sr-Mbr-Eng-Staff-Java matches longstanding positions... This could be a year or even more before they closed out the position, which then resulted in a letter going out to every applicant over a period of time.
But then why would I be unable to log into my account?
The most likely possibility I've thought of is that somebody setup a fake Lockheed profile on brassring (as far as I can tell, Lockheed does not use brassring), copied a Lockheed job posting, and applied to it with my email so that I would try to log into my account and answer security questions.
Thinking outside the box a little, have you made critical remarks about the military industrial complex, working under security clearances or the stupidity of the F-35 in front of a friend that might think it was funny to create or sign you up for a "job offer" from Lockheed Martin?
Coincidences happen as well... I once had to make sales calls to a firm which turned out to be run by the only living person I'm aware of that shares my name. I get sporadic emails informing me that my takeaway order will be delivered soon to somebody living in the same area and having similar tastes in takeaway food to my late grandparents too.