I guess I don't see this. I think a "follow the water" strategy is perfectly rational, since the only sort of life we understand well is our own kind, so it's really the only kind we're equipped to detect- especially by remote means. But I haven't heard much of a consensus suggesting that any habitable planet will almost certainly have life. Researchers are simply looking in the most logical places.Ann wrote:NASA, however, pursues its "Follow the water" strategy, and it's hard not to think, from how they present their strategy to the general public, that if an extrasolar planet is firmly inside the "habitable zone" of its star and has a rocky composition and an atmosphere, then it "almost certainly" has life, too.
It wasn't long ago that the big question was whether there were any other planetary systems, and how common those might be. We now know that they are extremely common- most stars probably have them. So now we have a new question- how common is life on other planets? And for now, it is a completely unanswered question, with a range of possible answers ranging from nonexistent to ubiquitous. I don't think many scientists take any firm stance on that question at all... though obviously, different researchers make different assumptions, which guide their specific work.
That seems indisputable. It doesn't, however, mean that life is either inevitable, or even likely, on planets which support liquid-based chemistry- water or otherwise.And there are definitely astronomers who say - or seem to say - that if planets definitely lack liquid water, then life may very well find other liquids to sustain itself on these planets.