Now a new National Research Council report is throwing a wrench in the works, calling on NASA and the NSF to take off their "terracentric" blinders and be open to the possibility that life could arise without water and in configurations lacking a carbon-based metabolism. The report, The Limits of Organic Life in Planetary Systems, was issued late last week.
From the conclusions:
The committee's investigation makes clear that life is possible in different forms from those on Earth. Different specific biomolecules may be considered highly likely in extraterrestrial life. Different architectures at the microscopic and macroscopic levels must also be considered likely.
So what are scientists supposed to do about it? How can they search for life that might take totally unfamiliar forms? The report recommends a three-pronged attack: laboratory studies that will help clarify how life got started in the first place, a thorough scouring of Earth's stranger environments (under the sea floor, in the upper atmosphere) for novel forms of life, and space missions to scan planets and moons likely to harbor the ingredients of life. Plus, Titan and Enceladus should get bumped to the front of NASA's exploration docket.
The authors write:
"Nothing would be more tragic in the American exploration of space than to encounter alien life and fail to recognize it..."
You might say tragedy of the tangible variety--to which the American space program is no stranger--trumps the abstracted tragedy of missed opportunity. But it's a good line. And, who knows? It may have already happened.