It would have been difficult to find two people with more polarized views on Mars exploration than Robert Park and Robert Zubrin. Zubrin is founder of the Mars Society and a staunch advocate of human exploration of Mars, while Park, editor of the American Physical Society’s “What’s New” newsletter, thinks such exploration is best left up to robots. Last week they met in person for the first time for a debate sponsored by the Ethics and Public Policy Center in Washington, DC. The debate transcript makes for interesting reading regarding how these two people view the relative utility of humans and robots in space exploration.

While the debate was interesting, it misses a key point. Much of the debate is focused on how much science humans and robots can do. However, science alone is unlikely to be the sole or even a leading reason for sending humans to Mars: the American taxpayers’ appetite for science in general has limits, as supporters of the Superconducting Super Collider found out a decade ago. Park and Zubrin touch on some other reasons for sending humans to Mars–adventure, economics, spreading human civilization beyond Earth–but to date no one has hit upon the right mix of reasons to sell a human mission to the public. This may be the biggest challenge the President’s new space initiative, or any other future plan, will face.