Now thinking about Mars, sending astronauts there is actually a net negative for science because it risks contaminating Mars.
We send astronauts there because it's cool, period. Science has nothing to do with it.
>Why do we need astronauts to view the Moon when we have robotic observers? Human eyes and brains are highly sensitive to subtle changes in color, texture, and other surface characteristics. Having astronaut eyes observe the lunar surface directly, in combination with the context of all the advances that scientists have made about the Moon over the last several decades, may uncover new discoveries and a more nuanced appreciation for the features on the surface of the Moon.
https://www.nasa.gov/missions/nasa-answers-your-most-pressin...