Instead of sending any more probes to the Red Planet, we should send the organic land-yacht known as Rosie O'Donnell, along with a bag of viable plant seeds.
Here's my reasoning:
Given the biological mass within her body as well as the bacteria-laden human waste that seems to cascade, copiously, from both ends of her digestive system, Mars would be able to spawn an entire eco-system based solely on her decomposing remains. Internally-stored bacteria would start the process and before long, the seeds would have a healthy substrate in which to flourish. Gases from within her body would replenish the atmosphere and contribute to the melting of ice at Mars' poles, thus flooding the now barren landscape with life-giving H2O. The landing spot would become a nucleus of rabidly aggressive terraformation and after only a generation or two, we'd have in habitable land, breathable air and drinkable water--that is, if you don't mind living in what would essentially be a planet sized fart.