Forget Mars get your ass to Europa
Mars is a dead red desert with little (if any) chance of life. NASA should focus their resources on the really exciting places in our Solar System. Europa and Enceladus. Those two moons are expected to have liquid water oceans below the surface. It would be mind blowing if we found large life forms there, not just bacteria, but something resembling our ocean creatures.
Could you image the impact if we sent a probe that tunnelled through the ice on Europa to the liquid water below and returned HD video of alien life.