Call Mike Griffin's office - it's his job
There' no need to worry and get all panicky, Jeff.
You can get the NASA switchboard via directory information, and then call and ask for the NASA Administrator's office.
Ask Mike Griffin - it's his job. The House and Senate made it his job last December. That's why they pay him the big bucks.
By the way, you probably wold be better off asking him about the fragments of comet Schwassmann Wachmann 3 instead of asteroid 2004 MN4. They're due very near the Earth in 2022. The good news is that most likely they're small enough so only 5 to 15 Kt blasts may occur. Most Likely.