From publisher blurb:
The Solar System turned out to be a lot less friendly than we expected. Dreams of Martian canals and Venusian jungles died in the harsh light shone by Mariners and Veneras and Voyagers.
But what we did get was an array of worlds of awesome majesty, one that's enough to scare off 99% percent of would-be explorers—but not you. Using the Cepheus Engine core rules or other similar game systems, the Into the Dark setting book lets you play OSR SF adventures in the near-future of the Solar System as we understand it now.
Europa. Titan. Pluto, points beyond? They all will kill you if you make one mistake, and they won't even register that you're there when they do it. You're going to go anyway.