I've only got a few real obsessions. My dogs. Doctor Who. Anything to do with astronomy. Lost in Space. The X Files. Star Trek - The Next Generation. The movie Contact.
I bet you're sensing a theme, here. Other than my dogs, all of these have to do with the universe, space travel, and alien life. And given how oddly my dogs act some days, I find myself wondering if they might not be alien spies as well. Especially Rosie, who so often seems to be judging us.
"Unless I start getting steak for dinner, the report I'll be sending to the Mothership will be highly unflattering."
In spite of all this, I still am very much of the opinion that life elsewhere in the universe is likely to be abundant. I base this on the known facts that there are trillions of stars out there, in billions of galaxies, and that exoplanetary systems are common (i.e. the formation of the Solar System wasn't just a lucky fluke). Optimistic estimates of some of the other variables in the Drake Equation are harder to defend, but I stand by my statement: a purely statistical argument suggests that many star systems have planets that support some kind of life.
One of the things that in my mind argues for life existing elsewhere in the universe -- even in environments that we might consider inhospitable -- is how many extreme habitats here on Earth turn out to host living things. There's life in the desiccated, perpetual cold of the dry valleys of Antarctica, in highly alkaline (or highly acidic) hot springs, in boreholes miles deep, in hydrothermal vents in the oceanic abyss. The odd little animals called tardigrades can survive extremes in temperature and pressure, radiation, and dehydration; they've even survived exposure to the vacuum of space.
And we're still finding new ones in unexpected places. Take, for example, the microorganism -- or, rather, the traces of it -- that was the subject of a study this week in the journal Geomicrobiology. A team out of Johannes Gutenberg Universität Mainz was studying samples of marble and limestone quarried in the parched deserts of Namibia, Oman, and Saudi Arabia, and found microscopic tunnels apparently excavated by some as-yet-unidentified microbe.
"We were surprised because these tubes are clearly not the result of a geological process," said Cees Passchier, who co-authored the paper. "We were looking at the structure of the rocks to find out how continents came together to form the supercontinent Gondwana five hundred to six hundred million years ago. At that time, carbonate deposits formed in the ancient oceans and turned into marble due to pressure and heat... We noticed strange structures in this marble that were not the result of geological events. These are old structures, perhaps one or two million years old... What is so exciting about our discovery is that we do not know which endolithic microorganism this is. Is it a known form of life or a completely unknown organism? It must be an organism that can survive without light because the tubes have formed deep inside the rock. We don't currently know whether this is a life form that has become extinct or is still alive somewhere."
Samples of marble with the "microburrows" [Image credit: C. Passchier et al.]
It seems like everywhere we look on Earth, we find life, which strengthens the hope of those of us who'd like to find life out there amongst the stars as well. That microorganisms can live by tunneling their way through solid rock certainly suggests we should expand the parameters of the phrase "capable of supporting life."
Although most of it may not be at the point of sending out messages that could be picked up by our radio telescopes, my surmise is that most even remotely hospitable locales in the universe will turn out to be inhabited. And just judging by the diversity of our terrestrial organisms, I also strongly suspect that what is out there will indeed turn out to be, in Darwin's immortal words, "endless forms most beautiful and most wonderful."
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