  There is a widely held view in the astronomical community that unmanned
robotic space vehicles are, and will always be, more efficient explorers of
planetary surfaces than astronauts (e.g. Coates, 2001; Clements 2009; Rees
2011). Partly this is due to a common assumption that robotic exploration is
cheaper than human exploration (although, as we shall see, this isn't
necessarily true if like is compared with like), and partly from the
expectation that continued developments in technology will relentlessly
increase the capability, and reduce the size and cost, of robotic missions to
the point that human exploration will not be able to compete. I will argue
below that the experience of human exploration during the Apollo missions, more
recent field analogue studies, and trends in robotic space exploration actually
all point to exactly the opposite conclusion.
