Q: And what would we do with ET, if we find it?

Chyba: We would first determine whether or not it shared a common ancestor with us. If not, we would have an entirely new kind of biology to understand, and begin to get hints as to the range of biologies that are possible. If so, we would begin to try to identify the world of origin, and wonder just how widespread "our" form of life might be.

Farmer: First and foremost, protect the Earth from it (and it from us!) until we really understand it. From that knowledge would flow the answers to all kinds of interesting questions: Is ET like terrestrial life, or totally different? If it is similar, does that mean that life hopped between planets, as suggested by the panspermia hypothesis, or is there simply tight convergence because of the stringent demands placed on pathways for prebiotic organic chemistry?

If ET is different, how different is it and what does this imply about alternative routes to living systems from prebiotic chemistry? Does it evolve like Earth-based life; and what is the range of adaptation? Finally, is the life form useful to humans in a biotechnology sense, or does it need to be contained (e.g. like a lethal pathogen) to protect the Earth's inhabitants and environment?

Jakosky: Obviously, the first issue is to determine whether it had an origin independent of terrestrial life. On Mars, for example, we can imagine that interplanetary exchange had occurred and that Martian and terrestrial life might have a common ancestor. If it doesn't, then the major scientific questions involve determining whether there are fundamentally different solutions to the issues of storing energy (ATP on Earth), reproduction and passing on genetic information (the structure of DNA and RNA) and catalyzing chemical reactions (enzymes).

Of course the other, perhaps most important, issue that we would address is the uniqueness of life on Earth. Having even a single example of an independent origin of life would have philosophical consequences on par with the recognition that the Earth goes around the Sun rather than vice versa and that life on Earth has evolved through natural selection from a common ancestor. Knowing of such life would help us to question the underlying issues of who we are as a species and a civilization and, in effect, what it means to be living and what it means to be human. <<<

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