"they basically built a rocket-powered hovercraft, something that's never been done before" They basically built a retro-rocket¹. Rockets existed, the principl

"they basically built a rocket-powered hovercraft, something that's never been done before" They basically built a retro-rocket¹. Rockets existed, the principle of retro-rocket-like descent braking existed too (usually deployed on parachute drops of heavy equipment like tanks). "I'd wager that the real reason is that Mars is more interesting to explore than Venus's atmosphere." As you also noted, it's about public attention, which was fed with a lot of Mars stories. Mars' surface was more observable and thus made it more easily for Sci-Fiction writers to speculate about. It had less to do with practical considerations like those related to its atmosphere. ¹ http://en.wikipedia.org/wiki/Retrorocket http://en.wikipedia.org/wiki/Retrorocket