This article was originally published at The Conversation. The publication contributed the article to Space.com's Expert Voices: Op-Ed & Insights.
Living in today’s age of ambitious robotic exploration of Mars, with an eventual human mission to the red planet likely to happen one day, it is hard to imagine a time when Mars was a mysterious and unreachable world. And yet, before the invention of the rocket, astronomers who wanted to explore Mars beyond what they could see through their telescopes had to use their imaginations.
