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Possibility of Life On Mars Looking More Remote
Riding with Robots writes "The never-say-die robotic geologist Opportunity continues its extended explorations in Victoria Crater on Mars. The latest findings from the mission suggest that while plenty of water did exist in this location, it was so salty that life would have a very hard time gaining a foothold. 'Not all water is fit to drink,' said Andrew Knoll, a member of the rover science team. 'At first, we focused on acidity, because the environment would have been very acidic. Now, we also appreciate the high salinity of the water when it left behind the minerals Opportunity found. This tightens the noose on the possibility of life.'"
It seems that NASA is well aware of extremophiles, but even considering the range of environments that support life here, there's still a limit. There is no life on Earth that exists without water, nor is there an alternative solvent available on Mars. There is no life on Earth that exists outside of a relatively tight temperature band (as far as the cosmos go, -50 C to 150 C is pretty narrow). There is no life on Earth that is able to survive a temperature swing of more than 100 C. Etc.
Maybe there's silicon-based life somewhere in the cosmos, but the chemical reactions that are required to sustain carbon-based life have certain limits. Temperature, pressure, the availability of certain minerals and the availability of water are chief among them.