Comment by clort
6 hours ago
something they didn't mention, what is in this upper stage? I'm presuming a rocket motor and some fuel is that right..? They do a calculation of energy release on impact, but I'm wondering if there is any fuel left and whether that would affect their equation?
Like most upper stages, Falcon 9 makes itself inert after a mission by venting any remaining propellant. Otherwise there's a risk that propellant could boil off, increasing pressure until the tank explodes, creating a debris cloud. Since pretty much any collision in space is catastrophic, it's easier to track and avoid one large piece of debris rather than a bunch of small ones.
I can't really think of much besides maybe some batteries. The fuel and oxidizer are supposed to be dumped shortly after payload deployment to prevent any issues with blowing up. Even if it wasn't dumped, its been a year, so it would have boiled off.