Where in our Solar System do you expect life will be found? Jupiter’s Europa, the hidden oceans of Saturn’s moons Enceladus or Titan, the subterranean lakes of Mars, the clouds of Venus?
What will form will the life mostly be? Carbon-based, non-carbon? Microbial? Possibly advanced?
Post your thoughts in Comments and we’ll publish the results next Monday, July 27th.
“One lifeform’s deadly radiation may be another lifeform’s lunch.”
David Grinspoon, member of the science team for NASA’s Mars rover, and interdisciplinary scientist for the European Space Agency’s Venus Express mission.
Prominent astrobiologists have warned that we humans may be
blinded by our familiarity with carbon and Earth-like conditions. In
other words, what we're looking for may not even lie in our version of
a "sweet spot". After all, even here on Earth, one species "sweet spot"
is another species worst nightmare. In any case, it is not beyond the
realm of feasibility that our first encounter with extraterrestrial
life will not be a solely carbon-based occasion.
Alternative
biochemists speculate that there are several atoms and solvents that
could potentially spawn life. Because carbon has worked for the
conditions on Earth, we speculate that the same must be true throughout
the universe. In reality, there are many elements that could
potentially do the trick. Even counter-intuitive elements such as
arsenic may be capable of supporting life under the right conditions.
Even on Earth some marine algae incorporate arsenic into complex
organic molecules such as arsenosugars and arsenobetaines. Several
other small life forms use arsenic to generate energy and facilitate
growth. Chlorine and sulfur are also possible elemental replacements
for carbon. Sulfur is capably of forming long-chain molecules like
carbon. Some terrestrial bacteria have already been discovered to
survive on sulfur rather than oxygen, by reducing sulfur to hydrogen
sulfide.
Nitrogen and phosphorus could also potentially form
biochemical molecules. Phosphorus is similar to carbon in that it can
form long chain molecules on its own, which would conceivably allow for
formation of complex macromolecules. When combined with nitrogen, it
can create quite a wide range of molecules, including rings.
So
what about water? Isn't at least water essential to life? Not
necessarily. Ammonia, for example, has many of the same properties as
water. An ammonia or ammonia-water mixture stays liquid at much colder
temperatures than plain water. Such biochemistries may exist outside
the conventional water-based “habitability zone”. One example of such a
location would be right here in our own solar system on Saturn’s
largest moon Titan.
Hydrogen fluoride methanol, hydrogen
sulfide, hydrogen chloride, and formamide have all been suggested as
suitable solvents that could theoretically support alternative
biochemistry. All of these "water replacements" have pros and cons when
considered in our terrestrial environment.
What needs to be considered
is that with a radically different environment, comes radically
different reactions. Water and carbon might be the very last things
capable of supporting life in some extreme planetary conditions.
Join in the Poll…Enjoy the comments! Add your thoughts.
Our Thanks, The Daily Galaxy Editorial Team
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