Ask Dr. SETI ®
All contemporary astrobilogy research seems to focus on water-based life. For example, a planet is described as being in the habitable zone of its star if its surface temperature is consistent with the existence of liquid water. Just because life on Earth is water-based doesn't mean all life in the Universe will be. Why are you restricting your studies to water planets alone?
The Doctor Responds:
The long answer involves the need for a solvent to sustain life, if for no other reason than to act as a transport mechanism for fuel (i.e., to carry an energy source throughout the organism, and to help dispose of waste products). There are at least five desirable characteristics of such a solvent, for the purpose of supporting life:
The flippant answer actually raises another question. Water-based life is, in essence, life as we know it. We know exactly how to look for life as we know it. But how do we look for life as we don't know it? We just don't know!
Of course, all three of these answers apply to organic life. If we start talking about inorganic (non-biological) lifeforms, such as intelligent machines, then all bets are off.
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this page last updated 5 March 2005
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