We're especially interested in water, whether it's ice, liquid or vapor. Learning more about where the water is today and where it was in the past will also guide future studies about whether Mars ever supported life.
We're bringing more capability to the planet. What we're really doing now is establishing the background environment that we have to deal with when we plan future missions.
It's a weather satellite, it's a geological surveyor, it's a pathfinder for future missions.