Hard Sci-Fi meets Zombie Apocalypse

I'm GMing at Wayward tomorrow, and trying something a little different. The PCs are Astronauts aboard the International Space Station when something goes terribly wrong. I plan on bombarding the earth with Dark Matter, then making them face a Zombie Apocalypse and Post Apocalyptic Decay. But, at first, it'll be hard sci-fi, and I intend for it all to feel like hard sci-fi. This may fail, it's a grand experiment, which was perhaps o'erhastily concocted. Basically, I have a whole bunch of library research I've doing lately about various science topics, and I wanted to put them all together into a one-shot. Fingers crossed.