As someone explained to me on another thread, the orbiters they have now are in polar orbits. A more equatorial orbit would create very frequent uplinks. One

As someone explained to me on another thread, the orbiters they have now are in polar orbits. A more equatorial orbit would create very frequent uplinks. One thing is that they didn't know Gale Crater was where they were going to land until pretty soon before launch. There were a number of other sites. And if they chose one further from the equator, that satellite wouldn't necessarily be in the right place.