Some arguments are here: https://phys.org/news/2005-11-unmanned-space-exploration_1.html https://phys.org/news/2005-11-unmanned-space-exploration_1.h... Retrie

Some arguments are here: https://phys.org/news/2005-11-unmanned-space-exploration_1.html https://phys.org/news/2005-11-unmanned-space-exploration_1.h... Retrieving a sample is cheaper with a robot - Luna-24 costed a fraction of Apollo. Knowing what to retrieve while having flexibility of choosing surface regolith, separate rock, samples dug out from a better place or else - that's where humans win.