[benihana]

They are completely separate missions. Mars is about sending humans somewhere other than the moon. It's less about scientific discovery and more about engineering and exploration discovery - we're doing it to learn about Mars sure, but moreso we're doing it to see if we can.

Mars is the next step in humanity's long term (hundred of thousands of years) survival. If we ever intend not to be at the mercy of gravity, we have to get off earth. We've been to the moon, which is gravitationally constrained to earth, and is only a three day journey (with many chances for safe aborts). We've conquered LEO and now know more about our planet than we could have dreamed up 20 years ago. Mars is a completely different challenge, and by going to Mars we'll develop the first bits of technology that will help us off our deathtrap of a cradle.

These two missions can coexist. We haven't developed the technology to send humans that far out into the solar system so we should continue to send probes.