Decades before anyone had built a rocket, earthlings had already argued in science fiction about who is more suited for space travel: humans or machines. Today, the debate drags on as private players like SpaceX and government agencies like NASA vie to send people to the moon, Mars and beyond. But such missions are costly, and human bodies remain sensitive to space’s harsh conditions. Maybe robots would simply prove better, cheaper, faster. In Science Smackdown, we let experts argue the evidence.