Terraforming, anyone?
Actually, the failure to find signs of life on Mars would be a great encouragement to the terraforming supporters..
You and I both know, if life forms are found, there will be a veritable flood of environmentalists, that will demand that Mars be "protected" as some intergalactic Wildlife Preserve, and ban drilling for oil, or anything else...
If you wish to terraform Mars, the best thing that could happen is that it be found to be "sterile" and lifeless..
Construction will begin immeadiately after said finding...