Robots for knowledge, science, humans for ego, excitement.
Clearly AI robots with human input are it for harsh environments. Sending humans is a big waste of money anymore.
At one time humans made sense, but computers and materials technology have made robots improve faster than have humans. And they will get better faster than man will evolve into, say, a CO2 breathing creature able to endure -200F.
That is if you want more science for the buck.
How much of the time, money and energy going into the Space Station is spent just maintaining life? And how much science could be accomplished with the same expenditure on robots doing science? With people sent up to effect repairs, change out experiments, etc.
Arf