Say that one of NASA's probes discovers definite evidence of life outside of Earth. Does NASA have any procedures in place on how to deal with such a situation? For instance, do they have to inform someone first before the go the press? Do they even go to the press?
I am not aware of any official procedure, and I don't really think one is needed or useful. The NASA administrator will go the White House first, and they will decide who to talk to first, how to assess the veracity of the evidence, what other government agencies should be consulted, and when and how to announce the findings.
The reason that I don't think that a procedure is useful, other than talking to the White House, is that the White House will decide what to do in real time without looking at some procedure that someone wrote a while back, knowing nothing about what the nature of the discovery might be or the current state of affairs. In other words, they will ignore the procedure.