I just finished it, too. Knowing it was written under the "Mira Grant" pseudonym, and being familiar with most of the Mira Grant titles, I kept reminding myself "don't expect a happy ending". Yes, it absolutely went there, though I wasn't sure where "there" was, until the end.

I thought that all impact craters were roughly circular, even if the object came in at an angle. What conditions are needed to produce a directional splatter pattern like this. (Maybe if the object comes in slow enough???)