Coverage of SpaceX and Blue Origin, the two private companies pursuing the reusable rocket, is near inescapable. Maybe you watched a launch on our site, or saw one of the not-quite-landings in a Facebook video. Space news has become so ubiquitous in tech culture, that it's easy to scroll right past, maybe leaving a Like in your wake, taking for granted the creative and financial cost that goes into sending an object into space — and attempting to bring it back to repeat that journey.

I've invited science reporter Loren Grush to explain how reusable rockets work, and why scientists and inventors hope to create them at a practical cost. For longtime listeners, we also discuss the film Knowing.