In marking the H. G. Wells anniversary, you highlight what Carl Sagan dubbed the “dance” between science fiction and science fact (see www.nature.com/scifispecial).

Wells's The War of the Worlds saw the Martian invasion stopped in its tracks by Earth pathogens (S. J. James Nature 537, 162–164; 2016). Now, almost 120 years after Wells's novel was published, the Mars rover Curiosity may have to be diverted because of fears that Earth microbes on the craft could contaminate possible wet areas — a potential habitat for hypothetical Martian life (Nature 537, 145–146; 2016). Such symmetry.