What if the space ice has little critters in it, or eggs laid by alien critters that hatch when inside you & grow, like from that film Alien. Or worse if it grows into a big, spiny alien that forces its way out of your arse? No to space ice, I say..

Glass, postcard and out the window. Someone else can deal with it

Never fear - Aliens are more likely to look like a bit of floating cling film than a HR Giger type - we can probably just frazzle 'em with a Zippo or something.