Seeing it as your only slim chance at survival, you dive headlong into what you had assumed to be a portal. As it turns out, for what feels like the first time, you are completely right about everything. This is a portal and, as expected, you end up floating in the infinite void of space. Cold is an understatement; the cold is actually worse than the lack of oxygen. There aren't a lot of choices at this juncture, but you can make one if you like.