After watching Niel Blomkampf's Tedx about alien life, it occurred to me that I hadn't written any essay material in quite some time, and this is a topic I find myself most passionate about. Biology and space exploration captivate me enormously, and anything that combines the two is sure to suffer my relentless fixation.
The first and most obvious question that every essayist/science journalist poses is "why haven't we found them yet?" To be fair, this question also rattles around in the brains of the best and brightest scientific minds, echoing like a b-horror villains footsteps on wet pavement; the question has implications for our own civilization, potentially gloomy ones. That said, let's consider a few things:
Life is probably ubiquitous.
The chemistry and conditions to get life started likely aren't unique to our world. Consider that when a nickel-iron meteor, rich in nitrogen, slams into water at hypersonic velocity, the cataclysmic energy produces amino acids. Not just any amino acids, but the left-hand configured amino acids that are exclusive to life. The Stardust spacecraft returned samples from a comet confirming that comets contain many organic compounds and peptides. And very recently, an experiment in which these two source reagents were dissolved in water, and put under a day-night evaporation and condensation cycle, yielded self assembling ribonucleotides, the building blocks of RNA.
Europa, Enceladus and Mars have strong evidence of past or present liquid water (the former two almost definitely have a liquid subterranean ocean). That means four (including Earth) 'hits' within one solar system. At least three have strong active sources of energy, solar and volcanic energy on Earth, tidal compression energy on Europa and Enceladus. It seems only a matter of time before a robotic probe uncovers nascent critters on one of these not-so-icy moons.
While I can't make any assertions (for obvious empirical reasons), I'd wager that that life is not only ubiquitous, but almost certainly carbon based most of the time. Carbon is much more abundant than silicon, and while nothing precludes the existence of silicon based life, there is simply much more carbon, and carbon binds more readily than silicon in most of the conditions out there. I will even go so far as to say that it is likely based on RNA or DNA. If there is one thing the Universe does really well, it's follow the path of least resistance. If RNA forms readily in non-unique lab conditions, chances are it's forming everywhere in the galaxy.
So, with some blogger confidence I will say that alien life is likely carbon based, and stores its hereditary information in either RNA or DNA. After that, things get tricky.
More in part 2...